# data[].attributes.attachment_link.readable_text
Image

Photograph by David Liitschwager

Microplastics, as the name implies, are tiny plastic particles. Officially, they are defined as plastics less than five millimeters (0.2 inches) in diameter-smaller in diameter than the standard pearl used in jewelry. There are two categories of microplastics: primary and secondary.

Primary microplastics are tiny particles designed for commercial use, such as cosmetics, as well as microfibers shed from clothing and other textiles, such as fishing nets. Secondarymicroplastics are particles that result from the breakdown of larger plastic items, such as water bottles. This breakdown is caused by exposure to environmental factors, mainly the sun's radiation and ocean waves.

The problem with microplastics is that-like plastic items of any size-they do not readily break down into harmless molecules. Plastics can take hundreds or thousands of years to decompose-and in the meantime, wreak havoc on the environment. On beaches, microplastics are visible as tiny multicolored plastic bits in sand. In the oceans, microplastic pollution is often consumed by marine animals.

Some of this environmental pollution is from littering, but much is the result of storms, water runoff, and winds that carry plastic-both intact objects and microplastics-into our oceans. Single-use plastics-plastic items meant to be used just once and then discarded, such as a straw-are the primary source of secondary plastics in the environment.

Microplastics have been detected in marine organisms from plankton to whales, in commercial seafood, and even in drinking water. Alarmingly, standard water treatment facilities cannot remove all traces of microplastics. To further complicate matters, microplastics in the ocean can bind with other harmful chemicals before being ingested by marine organisms.

Scientists are still unsure whether consumed microplastics are harmful to human or animal health-and if so, what specific dangers they may pose. Even so, many countries are taking action to reduce microplastics in the environment. A 2017 United Nations resolution discussed microplastics and the need for regulations to reduce this hazard to our oceans, their wildlife, and human health.

National Geographic Society

October 31, 2023

# data[].attributes.attachment_link.description
Microplastics are tiny plastic particles that result from both commercial product development and the breakdown of larger plastics. As a pollutant, microplastics can be harmful to the environment and animal health.

# data[].attributes.attachment_link.readable_text
What chemical reaction developed in a lab has had the greatest impact on the world? I think I can make a case for polymerization, the process by which small molecules are linked together to make long chains. Specifically, I have in mind the polymerization that produces plastics, a group of materials that can be shaped when soft and then hardened to retain a given shape.

How have plastics changed our world? Our food and beverages are packaged in plastics; our medications are coated with them; our personal care products come in plastic containers; our cars, airplanes and hospitals cannot function without them; and our homes are filled with an array of plastic items.

Unfortunately, our landfills, garbage dumps, beaches and oceans are also filled with plastics. And the micro and nanoplastics that form when these materials break down are invading our food, our water and consequently our bodies. Furthermore, the majority of plastics are made from raw materials derived from petroleum, a non-renewable resource, and their manufacture is an energy-intensive process that releases greenhouse gases.

Obviously, recycling, reusing and cutting down on non-essential uses of plastics are desirable goals. But we also need to discover ways to source the raw materials from renewable sources and develop plastics that degrade into harmless substances in the environment. This is where bioplastics come into the picture.

"Bio" means life, so bioplastics are plastics that are at least partially made from raw materials derived from living organisms, or are biodegradable. Biodegradable means that they can be broken down by bacteria, fungi or microbes into simple compounds such as carbon dioxide and water that can be reabsorbed by the environment, ideally without causing any pollution.

Bioplastics are classified according to either their origin or their biodegradability. Some may come from renewable resources and are not biodegradable, some may be produced from petroleum and are biodegradable, and there are those that come from renewable resources and are biodegradable. The latter are the most desirable, and also the hardest to achieve. None of the most widely used plastics - polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene and polycarbonate - fall into the bioplastic category. At this point, only about one per cent of all the plastics produced are bioplastics - hardly an amount that has a great impact.

Microbes can not only break plastics down, they can also produce them. Bacteria and fungi are like little chemical factories that produce special proteins called enzymes that catalyze chemical reactions, such as converting starch to glucose and then glucose to lactic acid in a process first described in 1857 by French chemist Louis Pasteur. Adding lactic acid-producing bacteria to cornstarch yields lactic acid that can then be polymerized to polylactic acid (PLA) using a metal catalyst. PLA is the most commonly used bioplastic, suitable for disposable cutlery and compost bags. It is biodegradable, but only in an industrial composting facility. It will not biodegrade in a home compost pile. In the anaerobic conditions of a landfill, it will eventually biodegrade, but the product then is methane, a potent greenhouse gas.

The second-most widely used bioplastic is PHA, which stands for polyhydroxyalkanoate. PHA is actually a family of polyesters that are naturally produced by some bacteria. For example, the soil bacterium Cupriavidus necator can produce a variety of PHAs depending on the nutrient it is fed, which can be methane, starches or fats from plants or animals.

The great advantage of PHAs is that they will biodegrade in ambient environments, even the ocean. This makes them suitable for single-use products like food packaging, straws and cutlery. Their downside is cost: PHAs are about 10 times more expensive than PLAs.

Some clever chemistry has led to another biodegradable plastic that, while not as readily biodegradable as PHAs, has physical properties that come close to matching those of conventional plastics. It goes by the tongue-twisting name of polybutylene adipate terephthalate, or PBAT.

Researchers looked at the molecular structure of polyethylene terephthalate, the plastic used to make beverage bottles that are often callously tossed away. Being non-biodegradable, they pollute the environment. It seems that microbes cannot get at the bonds that hold these molecules together because their approach is blocked by the terephthalate components of the polymer. However, replacing some of the terephthalate with the smaller adipate, and increasing the distance between these components by replacing the two-carbon ethylene connection with the four-carbon butylene, allows microbes to chew up the molecule. But - and there always is a but - all the components still come from petroleum! Nevertheless, PBAT qualifies as a bioplastic because it is biodegradable.

Bioplastic would be especially welcome in diapers, given that around 250 million are discarded every day, mostly ending up in landfills. The introduction of acrylic acid-based superabsorbent polymers in the 1980s reduced the incidence of diaper rash by 50 per cent, but these polymers are not biodegradable and are made from acrylic acid that is derived from petroleum. Scientists at Procter & Gamble, the maker of Pampers, have developed a catalyst that can convert lactic acid into acrylic acid that is then polymerized. Since the lactic acid is fermented from plant material, this version of the superabsorbent polymer would be a bioplastic even though it is not biodegradable. However, this would open the door to using terms like "nature-derived" or "bio-based" that are very marketable.

In a similar vein, Coca-Cola has overhyped its "plant-based bottle." Like other beverage bottles, it is made of polyethylene terephthalate, with the difference being that the components are produced from corn or sugar cane. The finished product, though, is not biodegradable. It is recyclable.

Something else to consider is that even bioplastics that are totally derived from plants, and are biodegradable, are not free of environmental problems. The crops that furnish the needed raw materials require pesticides and fertilizers, chemicals that have their own issues. Then there is the concern that the land to grow these plants could be put to better use, such as agriculture to produce food for the growing global population.

Yet another point is that even though bioplastics may come from renewable resources, there is still a lot of chemistry involved in converting them to the final product. Polymerization catalysts, plasticizers, antioxidants, antistatic agents, lubricants, colourants, flame retardants and decomposition products are as likely to be found in bioplastics as in conventional ones. A study that examined the toxicological profile of extracts from samples of the two types of plastic revealed no difference.

There is no question that there is some interesting chemistry in the quest for better bioplastics, but these materials will not solve the world's plastic problem.
@JoeSchwarcz

# data[].attributes.attachment_link.title
Breaking Down Bioplastics' Benefits and Problems

# data[].attributes.attachment_link.description
This article was first published in The Montreal Gazette. What chemical reaction developed in a lab has had the greatest impact on the world? I think I can make a case for polymerization, the process by which small molecules are linked together to make long chains.

# data[].attributes.attachment_link.title
Tissue accumulation of microplastics in mice and biomarker responses suggest widespread health risks of exposure - Scientific Reports

# data[].attributes.attachment_link.description
Scientific Reports - Tissue accumulation of microplastics in mice and biomarker responses suggest widespread health risks of exposure

# data[].attributes.attachment_link.title
Microplastics: what they are and how you can reduce them

# data[].attributes.attachment_link.readable_text
Plastic pollution has become ubiquitous in natural and built environments, raising concerns about potential harm to humans and nature alike. Once in the environment, research shows that plastic pollution is persistent and may take between 100 to 1,000 years or more to decompose, depending on environmental conditions.

Once in the environment, plastic pollution can fragment into smaller pieces of plastic. Microplastics are plastic particles ranging in size from five millimeters to one nanometer; nanoplastics are plastic particles smaller than one micrometer. Both are found in every ecosystem on the planet from the Antarctic tundra to tropical coral reefs.
On this page:
Environmental Impacts

Plastic pollution poses a threat to the marine environment. It puts marine species at higher risk of ingesting plastic, suffocating, or becoming entangled in plastic pollution. Research indicates that more than 1,500 species in marine and terrestrial environments are known to ingest plastics.

The Organization for Economic Cooperation and Development estimated that in 2019, plastic products were responsible for 3.4% of global greenhouse gas emissions throughout their life cycles, with 90% of these emissions coming from the production and conversion of fossil fuels into new plastic products. OECD also reports that, unless human behavior changes, greenhouse gas emissions associated with the life cycle of plastic products are expected to double by 2060. The World Economic Forum projects that without intervention, the global plastics industry will account for 20% of total oil consumption and up to 15% of global carbon emissions by 2050.

Human Health Impacts

According to the United Nations Environment Programme, microplastics have also been found in human livers, kidneys, and placentas. Additionally, the International Union for Conservation of Nature (pdf)(291 KB) finds that carcinogenic chemicals found in plastic products can leach into tap water, which may cause developmental, reproductive, neurological, and immune disorders. Some animal studies have raised similar concerns about endocrine-disrupting effects. More research is needed to better understand the potential human health impact of microplastics.

# data[].attributes.attachment_link.description
This webpage describes about how plastics waste affect human health and aquatic life.

# data[].attributes.attachment_link.title
Microplastics impact cloud formation, likely affecting weather and climate | Penn State University

# data[].attributes.attachment_link.description
Scientists have spotted microplastics, tiny pieces of plastic smaller than 5 millimeters, in some of the most pristine environments on Earth, from the depths of the Mariana Trench to the snow on Mt. Everest to the mountaintop clouds of China and Japan. Microplastics have been detected in human brains, the bellies of sea turtles and the roots of plants. Now, new research led by Penn State scientists reveals that microplastics in the atmosphere could be affecting weather and climate.

# data[].attributes.attachment_link.readable_text
According to Elisa Tonda, UNEP's Head of the Consumption and Production Unit, engaging all stakeholders is necessary to shift the textile industry towards circularity and to address microplastics releases from textiles.

"Policymakers need to implement stronger governance and policies, as well as create a policy environment which incentivizes the design of sustainable fabrics and clothing and promotes a more standardized approach to the determination of releases from different textile products and suitable alternatives," said Tonda. "Brands should strengthen their efforts in designing sustainable clothing and take responsibility for their products at end-of-life," she added
Cosmetics
Cosmetics and personal care products are other staples of grooming routines that can be loaded with microplastics. These products often contain primary microplastics, which are intentionally manufactured and added, often to provide texture - from hand sanitizer and soap to toothpaste and deodorant.

Plastic particles from these products can be absorbed into the skin or, in the case of products like lipstick or lip balm, directly ingested. Microplastics that remain on the skin are eventually washed down the drain and could make their way to the ocean.

According to UNEP's Global Chemicals Outlook II report, significant amounts of microplastics from cosmetics and other sources are more likely to enter waterways in areas with inadequate wastewater treatment facilities.

The report noted that some exfoliating agents contain more than 10 per cent microbeads - a type of primary microplastic. Furthermore, in a recent study, the Plastic Soup Foundation's Beat the Microbead campaign found that 83 per cent of 138 sanitizer and hand gel brands contained microplastics.

Reducing use, purchasing products with minimal packaging and examining ingredient lists are a few ways consumers can limit their potential exposure to microplastics, according to Madhuri Prabhakar, the foundation's Microplastics Campaigner.

Prabhakar added that generating a "future-proof definition for microplastics," will be essential in lobbying governments and businesses for change and potential bans or restrictions.

UNEP's Clean Seas Campaign's interactive " What's in your bathroom? " project showcases the prevalence of plastic in common personal care products to encourage consumers to opt for environmentally friendly alternatives.

Businesses and manufacturers also have a responsibility to decrease primary microplastic use. Meaningfully addressing the issue requires action beginning from the product design phase, according to UNEP's Assessment Report on Issues of Concern.
Turning the tide
Through this new focus, Clean Seas Campaign aims to drive change for consumers, policymakers and businesses alike.

Its partnerships with various organizations and businesses can encourage lifestyle and industry changes and lead to greater impetus for essential research. It can also bolster our limited knowledge of microplastics' true impacts on human health and help to identify the best paths forward.

Given their pervasiveness in everyday household items, finding answers to microplastics' complex threats is a critical and pressing challenge.

Countries and businesses can join the Clean Seas campaign, as well as the New Plastics Economy Global Commitment to make ambitious pledges and commitments to combat all aspects of marine litter and plastic pollution. Individuals can also take the Clean Seas pledge to reduce their plastic footprint. Together, we can make the changes necessary to reduce the impacts of plastics and microplastics on environmental and human health.
About World Environment Day
World Environment Day on 5 June is the biggest international day for the environment. Led by UNEP and held annually since 1973, the event has grown to be the largest global platform for environmental outreach, with millions of people from across the world engaging to protect the planet. This year, World Environment Day will focus on solutions to the plastic pollution crisis.
About the Clean Seas Campaign UNEP's campaign is the biggest, most powerful global coalition devoted to ending marine plastic pollution. It connects and rallies individuals, civil society groups, industry and governments to catalyse change and transform habits, practices, standards and policies around the globe to dramatically reduce marine litter and its negative impacts.

# data[].attributes.attachment_link.title
Microplastics: The long legacy left behind by plastic pollution

# data[].attributes.attachment_link.description
Microplastic left behind by plastic pollution in the ocean poses a major threat to humans and marine organisms.

# data[].attributes.attachment_link.description
Environmental health expert Leigh Shemitz and green chemist Paul Anastas walk us through a tiny problem with big environmental consequences.

# data[].attributes.attachment_link.readable_text
by

Maximilian Lackner is a technical chemist and process engineer. He has been a lecturer at Vienna of [...]

Anindya Mukherjee is a Co-Founder and Executive Board Member of the GO!PHA (2018) and a Founder and [...]

Martin Koller has acted as a Research Manager and Chemistry Project Manager (Research Management and [...]

4 1,2 and 1,2,3,* ,

Go!PHA, Oudebrugsteeg 9, 1012 JN Amsterdam, The Netherlands

Go!PHA, 12324 Hampton Way, Wake Forest, NC 27587, USA

CIRCE Biotechnologie GmbH, Kerpengasse 125, 1210 Vienna, Austria

Institute of Chemistry, NAWI Graz, University of Graz, Heinrichstrasse 28/IV, 8010 Graz, Austria

Author to whom correspondence should be addressed.

1. Introduction

Plastics are a versatile group of materials with countless short-lived and durable applications. This versatility is a result of the possibility to produce polymers with different chain lengths and molecular weight distributions from various monomers, and from the ability to derive composites, e.g., through the addition of fillers that modify their mechanical properties over a wide range. Examples of articles with a short service lifetime are food and non-food packaging, while examples of articles with long lifetimes are plastic window frames and plastic pipes for drinking water, sewage, and natural gas. In some applications, alternatives already exist (e.g., glass or metal packaging), while for other cases, no practical alternatives or substitutes are in place, e.g., for electrical applications, where the unique properties of plastics (e.g., their high thermal and high electrical insulation, light weight, low cost per item, durability, and resistance against various media) necessitate their use. It is hard to imagine our daily life without plastics. The annual plastic production volume was 390.7 million tons in 2021 [ 1], 90.2% of which were virgin fossil-derived polymers, with only 8.3% being post-consumer recycled plastics and approx. 1.5% being renewable or "bio-based/bio-attributed" plastics [ 1]. Overall, recycled plastic materials accounted for 11.7% of all plastics in Europe [ 2], a figure that has gone up by only 1% during the last decade. Without drastic changes in our use and reuse patterns, the path to proclaimed "circularity" is out of reach. At a global level, no more than 9% of all plastics are recycled [ 3]. The major issue with plastics waste is the mismanagement of plastic items towards and at the end of their lifetime, which can be attributed to a lack of waste collection and recycling infrastructure in most developing and emerging countries and inadequate or inappropriate waste collection and sorting infrastructure even in the developed/industrialized countries, coupled with human behavioural aspects, and the leakage of micro- and nanoplastics particles that are hard-to-impossible to catch and retain with today's technologies. Also, the broad range of plastic types and compounds, with different colors, fillers, and additives, aggravates the difficulties in attempts at (mechanical) recycling. Of note, the availability and price of raw fossil plastics are often more advantageous than those of recycled plastics, due to the low prices of fossil plastics (particularly commodities such as poly(ethene) (PE), poly(propene) (PP), poly(vinyl chloride) (PVC), and poly(ethene terephthalate) (PET)). Also, the demand for recycled plastics has increased strongly in some areas, with "green" products being more accepted by the customers, leading to comparatively higher prices and some shortages in supply. Figure 1 shows that globally, the amount of mismanaged materials is more than double the amount of recycled plastics.

The use of plastics largely follows a linear system (the "take-use-dispose" paradigm). A very recent report by the UN states [ 4]:

Up to 80% of mismanaged plastics could be reduced by 2040.

The annual costs from mismanaged plastics are 300-600 billion USD.

Simply improving today's recycling practices will not suffice. For instance, it was found that a single plastic waste recycling company in the UK emits up to 1.5 million kg of microplastics per year [ 5], which is half of the entire quantity of microplastics generated by this company; hence, half of the produced microplastics cannot be retained via filters or other means and enter the environment. In general, the formation and emission of microplastics has been undervalued and only recently has awareness on the topic emerged. Several companies are already developing solutions for capturing microplastics at the source, e.g., behind car tires or in washing machines; however, such attempts cannot catch the entire micro- and nanoplastics freight, and most points where microplastics occur, such as at sewage treatment plants, are not equipped with capturing technology at all. The European plastics industry has launched an effort called operation clean sweep (OCS) to reduce the emission (spills and losses) of plastics pellets, flakes and powder throughout the value chain, which constitute another major source of microplastics entering the environment. Also, technologies are being developed to capture bulk plastic items already littered into water bodies, e.g., via bubble curtains [ 6], yet all such attempts are at the very beginning and far from large-scale roll-out.

In order to reach recycling rates for plastics that are comparable to those of wood, paper, glass, and metals, paradigm changes are needed, with concerted action in legislation and technology development required, accompanied by changes in people's attitude towards plastics and inadvertent plastics "dumping".

Plastics are a virtually indispensable class of materials, and they have a bad reputation amongst consumers as numerous studies show, e.g., a recent one where consumers reported viewing plastics as the least environmentally friendly packaging material [ 7]. It seems that intrinsic material properties are mixed with plastics' mismanagement and its consequences, but the root causes for that problem are hardly known and hence not addressed. To stick with that example, plastic materials can offer several advantages over other packaging materials, and a key question is how to make them circular, less carbon-intense, and, in general, more sustainable. According to the OECD, "sustainable plastics" can be defined as "plastics used in products that provide societal benefits while enhancing human and environmental health and safety across the entire product life cycle" [ 8].

This article focuses on the definitions of bioplastics alongside the dimensions of being "biobased" and/or being "biodegradable". There is no plain "black and white" here, with many misconceptions. Therefore, this article intends to provide a detailed overview on bioplastics, and then delves into existing definitions. The key novelty and unique aspect of this review lies in offering an up-to-date summary of existing bioplastics definitions, with the aim of providing readers with a fast and handy reference.

2. State of the Art in Bioplastics

A "plastic" by definition is a polymer-based formulation, which consists of one or more polymers (homopolymer, copolymers, blends) plus additives and fillers. In nature, several polymers can be found, e.g., starch, cellulose, lignocellulose, or proteins (so-called biopolymers and/or naturally occurring polymers). A bioplastic (bioplastics) can be defined as a biopolymer-derived formulation, e.g., starch + plasticizer, poly(lactic acid) (PLA) + additives for processing and coloration, or (natural) fiber-reinforced poly(3-hydroxybutyrate) (P3HB), to give three well-established examples. A plastic material derives its properties from the combination of polymer(s) and additives, which applies equally to fossil and to biobased plastics. Filled products are called "compounds" or "composite materials".

2.1. What Are Bioplastics?

A biopolymer is a macromolecule that is composed of biobased or "natural" building blocks. Plastics can be thermoplastics (the largest group), elastomers, or thermosets, and bioplastics can fall into any of these groups. Sometimes, the terms "biopolymer" and "bioplastics" are used synonymously; however, we prefer a delineation with the term "bioplastics" being used for the human-made product (formulation, compound) of biopolymer + other ingredients, for use in technical applications (processing and manufacturing of goods). "Bioplastics" are either biobased and/or biodegradable, at least to a certain degree and as per a given definition (standard, test method). Figure 2 summarizes the definition of bioplastics by the IfBB (Institute for Bioplastics and Biocomposites, Hannover, Germany) [ 9].

The "old economy" bioplastics include rubber (used in tires), cellulose acetate (deployed in cigarette filters), and linoleum (found in floor systems). Vehicle tire abrasion, by the way, is one of the major sources of non-degradable microplastics, comparable in amount to fibers from polyester-based clothing [ 10] and plastics nurdles (pellets). While the sap of the rubber tree (Hevea brasiliensis) is biodegradable, the vulcanized natural rubber is cross-linked and persistent in the environment. The "new economy" bioplastics include "drop in" materials, which are essentially classic plastics made from a renewable resource, e.g., PE made from ethanol derived from sugar cane ("bio-PE"). They are biobased and have the advantage of behaving just in the same way as their fossil counterparts, so that converters do not need to change any settings in their manufacturing processes. Such materials are equally recyclable as fossil plastics; however, they undergo the same problematic end-of-life scenario as their fossil-based blueprints do: They are recalcitrant towards biodegradation, and a full life cycle assessment (LCA) is needed to describe and compare environmental impacts [ 11]. Most notably, they also generate persistent microplastics. The "chemical novel" bioplastics in Figure 2 are bioplastics that have no 1:1 correspondence among fossil plastics, with varying degrees of biobased carbon content and biodegradability. Examples are PLA or polyhydroxyalkanoates (PHAs) [ 12], which also require their own settings on processing equipment, as will be detailed below.

Figure 3 depicts bioplastics according to their two main characteristics "biodegradability" and "carbon source".

Bioplastics are found in the blue and green boxes of Figure 3, not only in their overlapping region. They do not need to be biodegradable, and neither do they need to be biobased, as long as the other criterion is fulfilled. They can be produced by microorganisms or by chemical synthesis, from inorganic (e.g., CO ₂) or organic (e.g., CH ₄, sugar, starch) raw materials. Plants might be used as hosts, too. Apart from plant-based raw materials, animal-derived waste products (e.g., chitin) can be deployed.

Common bioplastics are summarized in the following Table 1 (note that in practice, blends are often used).

PLA is one of the most commonly used and best-established bioplastic materials.

PHAs (polyhydroxyalkanoates) are a class of biopolymers, where the most common representatives are the homopolyesters poly(3-hydroxybutyrate) (P3HB), poly(4-hydroxybutyrate) (P4HB), and, to a lesser extent, poly(3-hydroxyvalerate) (PHV), along with their copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx), medium-chain-length PHAs like PHO (poly(3-hydroxyoctanoate)) homopolyesters, and their copolymers and blends [ 8]. An emerging field in PHA development concerns mcl-PHAs (medium-chain-length PHAs), which display properties of elastomers and bio-latexes [ 23].

Other bioplastics of lower volumes are, e.g., poly(glycolic acid) (PGA) and the copolymer of glycolic acid and lactic acid (PLGA), PPC (poly(propylene carbonate)) and PFA (poly(furfuryl alcohol)), chitosan, and protein-based (e.g., whey retentate-based) bioplastics. Most bioplastics are thermoplastics. An example of a degradable thermoset is the product made from citric acid + glycerol [ 24].

Bioplastics, analogous to conventional plastics, can also contain organic fillers, like wood chips or wood dust (WPC, wood-plastic composite), paper fibers, and natural fibers like kenaf, sisal, or hemp [ 25], which enable them to be fully biobased and biodegradable. Natural inorganic fillers, such as nanoclays [ 26], which trigger specific material properties like gas barrier behavior, are feasible, too.

Below, in Table 2, several definitions from SAPEA (Science Advice for Policy by European Academies) [ 27] related to the field of biopolymers and bioplastics are provided.

The terms "biodegradable" and "biobased" will be revisited later in this manuscript in more depth. For a good primer on bioplastics, see, e.g., references [ 28, 29].

2.2. Greenwashing

With environmental problems becoming visible and a growing concern for the general public, organizations are starting to feel more pressure to justify their actions and to prove their good-doing, in an attempt to secure or enlarge their business. Consumers have become eco-anxious and spend money on more costly, supposedly more environmentally benign merchandise. Corporate social responsibility (CSR) has become a buzz term in this respect, where organizations address social and environmental concerns in their business operations on a voluntary basis. An organization or its individuals might become tempted to use marketing spins to present themselves as "eco", "green", or "good" to the outside world. The expression of "greenwashing" describes dishonest practices of organizations to appear "green" [ 30]. It purportedly was coined in 1986 by Jay Westervelt, an environmentalist, who observed hotels' notices encouraging guests to reuse towels, while at the same time harming the environment in stronger ways, which he felt was obscured by directing peoples' attention to a lesser point of concern. Greenwashing is being blamed, e.g., by environmental groups, but still very present. For a systematic review on concepts and forms of greenwashing, see, e.g., [ 31]. The trading of carbon emissions can also fall into the realm of greenwashing, when "free credits" are allocated to large emitters, the carbon price is low, carbon projects are only temporary or miscalculated, or consumers feel "clean" after having bought voluntary credits, while continuing with carbon-intense patterns. In addition, it needs to be stated that only a fraction of anthropogenic CO ₂, CH ₄, and other GHG (greenhouse gases) is covered by emissions trading and related schemes. The credibility of the various certificates for renewable energy and circular/sustainable materials can differ among the plentiful, sometimes non-accredited schemes. For a definition of circularity/circular economy, see [ 32]. One has to acknowledge that the industry is still developing, yet rigid and traceable standards are imperative right from the start, and realistic assumptions particularly for the mid and long term are vital. The expression "carbon footprint", by the way, was invented by British Petroleum back in 2005 as a marketing sham [ 33]; they reframed the fossil fuel industry's responsibility for CO ₂ emissions as consumers' very own responsibility or "problem", by asking them about "their carbon footprint". The industry is not in the spotlight when this term is being used and applied, e.g., via various "CO ₂ footprint calculation" tools. Hence, we should avoid blindly repeating marketing speak with the term "carbon footprint", and reframe that to the "fossil fuel footprint". The responsibility of consumers with regards to environmental harm exists, yet we must not overemphasize it or put all of the blame/burden on their shoulders. It is the legal framework in which market incumbents operate and decide to place products on the market that is more the culprit. The consumers, in the end, can only chose among what they are being offered. Lately, a lot of products have been placed on the market with claims related to sustainability, which give the impression of being "eco-friendly", yet we need true solutions to the plastic waste crisis that have to come from the materials side. It is obvious that "end of pipe" solutions of more waste collection, sorting, and recycling cannot completely solve the problem of persistent plastic waste in nature, as there will always be a certain rate of leakage, both of bulk items as well as of micro- and nanoplastics. Also, the use of additives in plastic formulations needs to be watched carefully, with full transparency and limitations on problematic ingredients.

2.3. Biodegradability and Biobased Carbon as Complete Solution

Eventually, fossil plastics, with their stable carbon-carbon backbones, will degrade (in the order of up to hundreds of years), and all fossil carbon was once living matter (millions of years ago). Absolute statements have to be treated with caution, as with the degree to which different materials can be compared to one another, like in the case of, e.g., the toxicity of certain compounds. There is no such thing as a clear definition of "biodegradability" because that property is multifaceted. Let us draw an analogy to woody biomass: A large stem of a tree will take years, or even decades, to "disappear", while leaves will be biodegraded within less than one year; the same is valid for the stem when undergoing crushing processes prior to biodegradation. [ 27] states: "We consider plastic biodegradation a system property, in that it results from the interplay of a specific material property of the plastic that makes it potentially biodegradable as well as the abiotic and biotic conditions in the specific receiving environment that leverage this potential and control the rates and extents of actual plastic biodegradation".

The biodegradation of plastics is believed to progress in two steps, which can be preceded and accompanied by mechanical fragmentation (see also [ 34]):

(1)

Breakdown of the polymeric macromolecules into low-molecular-weight moieties.

(2)

Uptake of these compounds by microorganisms and in metabolic consumption, to finally yield CO ₂, CH ₄, and H ₂ O (complete mineralization).

The mere (bio)degradability of plastics is seen as insufficient to solve the plastic waste problem that the world is facing today because that property might tempt people to neglect the waste hierarchy and to use the materials in a linear fashion alone, with large quantities of plastic waste being littered/mismanaged. In 2020, the EU Group of Chief Scientific Advisors wrote regarding biodegradable plastics: "The 2018 EU Plastics Strategy sets out a cautious approach for the use of biodegradable plastics (BDP). While it acknowledges that targeted BDP applications have shown some benefits, it also identifies several challenges and points out that "It is important to ensure that consumers are provided with clear and correct information, and to make sure that biodegradable plastics are not put forward as a solution to littering" [ 35]. They hence recommend that we should "limit the use of BDPs in the open environment to specific applications for which reduction, reuse, and recycling are not feasible". The nova-Institute has identified such applications in its study BioSinn [ 36], which are listed in an exemplary fashion here in Table 3.

Examples are plastic components in fireworks, fruit and vegetable stickers, floral foam, dolly ropes, and wet wipes, where reuse and recycling of the materials is hardly feasible. While many packaging and other applications allow up- and downcycling of the materials, there are use cases like those presented in Table 3 above where a substantial fraction of a product will end up in the open environment and cannot be collected. Still, degradability makes sense for many more products, when one considers the considerable fraction of leaked plastics (bulk items and microplastics [ 37]), e.g., wrappings of sweets and small snacks, golf tees, and various single-use items (where no suitable alternative exists, e.g., a wound dressing). Primary microplastics stem from textiles (which are often made from PTT, PET, or poly(tetrafluoroethylene) (PTFE)-Gore-Tex™) and tire abrasion, which is considered one of the key sources of secondary microplastic [ 38], and even abrasion of shoe soles [ 39]. Paints and coatings are another important source of plastic-containing microparticles. Such microplastics are also generated without any littering, both in the use phase and during recycling, so degradability of plastics will, in any case, be beneficial to avoid accumulation and build-up of such materials in the environment. Degradable plastics can mitigate the consequences of both primary and secondary microplastics. Microplastics from degradable polymer materials can, however, also have detrimental effects on the environment, e.g., when that additional carbon freight is brought to an ecosystem or the particles act as carriers for absorbed toxins [ 40]. A combined approach is needed, where the freight of plastics ending up in the open environment is significantly reduced, and where that material will mineralize as soon as possible. Depending on the particles' size and type of biodegradable plastics, as well as the ecosystem, the degradation can last from days to years, but not hundreds of years as in the reference case with the xenobiotic fossil plastics.

3. It's All about the Carbon: Renewable Carbon Views and Concepts

Products require energy and raw materials for their manufacturing. The energy can be renewable or fossil, and the same principle applies to materials. Biomass is an example of a classic renewable resource. However, this needs to be regarded in a differentiated manner. When, for instance, an "old" ecosystem is looted to obtain biomass for combustion or material use, it will take a long time (i.e., in the order of at least decades) until an equivalent biomass has regrown, such as via reforestation; so, there can be a justified doubt about true circularity. A Norwegian study [ 41] found that "increasing the use of wood from a boreal forest to replace coal in power stations will create a carbon debt that will only be repaid after almost two centuries of regrowth". Negative environmental impacts of direct and indirect land use change, for instance, are also well-established, and the use of primary agricultural products for materials can bear negative consequences for feed and food prices, water, land, and fertilizer usage; hence, biomass by itself is not automatically a solution to all fossil energy carriers. While it is clear that carbon from fossil resources is not renewable, there is a debate on carbon from waste streams. Waste incineration (waste-to-energy), for instance, is sometimes promoted as renewable energy, despite the fact that waste can and does contain substantial amounts of fossil carbon and is a carbon-intense process. Through incineration, waste streams are rendered inert and reduced in volume by the process, and energy is obtained, but there will still be a net CO ₂ addition to the atmosphere. What is needed is sustainably sourced, scalable biomass, preferably waste streams from a local source. The key message to take away from this mindset is the following: Our materials need to be defossilized instead of decarbonized.

3.1. The Carbon Circle

Carbon is literally the backbone of organic materials and life, and there is a continuous cycle of carbon [ 42] on Earth, one that has been disrupted by mankind in the last 300 years due to the introduction of carbon, mainly via CO ₂ and CH ₄, from large sinks in the geosphere to the atmosphere, where an unprecedented rate of rise has been observed, currently standing at above 400 ppm of CO ₂. Human activities lead to an imbalance, and fossil resources (coal, oil, natural gas) that are burnt or converted into materials bring back "old" sequestered carbon into the environment. It is estimated that in Europe, 4-6% of all consumed oil and gas is converted into plastics [ 43]. With landfilling bans becoming effective, a large fraction of these plastics, most of which are short-lived products, is incinerated and converted to CO ₂.

It has proven advantageous to distinguish between carbon from fossil resources that is "dumped" into the atmosphere and carbon that is being reused so that it can be regarded as "renewable". According to the nova-Institute, the following definition applies: "Renewable carbon entails all carbon sources that avoid or substitute the use of any additional fossil carbon from the geosphere. Renewable carbon can come from the biosphere, atmosphere or technosphere-but not from the geosphere. Renewable carbon circulates between biosphere, atmosphere or technosphere, creating a carbon circular economy" [ 44].

3.2. A Side Step at Renewable Energy-Is There a Modern Equivalent to Sales of Indulgences?

Typically, an energy producer will utilize a mix of technologies to provide electricity to its customers, from caloric power stations running on fossil fuels to renewable electricity from, e.g., photovoltaics, wind energy, or hydropower. The share of fossil fuels in the global energy mix has been around 80% for decades and is projected to reduce to 75% by 2030 according to the IEA World Energy Outlook (WEO 2022) [ 45].

The energy producer can calculate its average CO ₂ footprint in "kg of CO ₂ per kWh of electricity sold" and communicate that number to interested parties. It can also decide to sell the fraction of its "green" electricity to eco-minded customers, who can then claim to be using "100% of renewable" and/or "100% emission-free" electricity (compare the initiatives of scope I, II, and III carbon reporting in annual reports and CSR documents of large corporations, where legal requirements start kicking in). Power has no tag attached to it, so the "green" electricity is actually from the mix of power generation sources, yet the allocation (see "Energy Attribute Certificates" (EACs)) makes some higher-paying customers feel at peace as they are assured they are using carbon-free power. An analogy to the medieval sale of indulgences by the Roman Catholic church comes to mind. Speaking in favor of the practice, one can argue that more demand for "green" electricity will drive the market towards more production of the same in the mid and long run.

In a similar concept, "renewable" carbon or "biobased" carbon can be "attributed" or ascribed to products, giving birth to the term "bio-attributed plastics". There are standards for such practices, e.g., the ISCC PLUS Version 3.4 scheme ([ 46] and also see below).

3.3. Biobased

When a renewable feedstock is used to make a bioplastic material, it will be "biobased"-at least partly. The term "biobased" is used interchangeably with "renewable" here. Renewable carbon does not necessarily have to be biobased. Direct air capture of CO ₂ and subsequent electrochemical conversion could be performed to obtain the monomers for a bioplastic material; however, there is no such commercial process implemented yet. One could derive the degree of "biobasedness" from the mass of the respective raw materials. For instance, in a compound of 30% (weight) starch in PE, one could argue that 30% of the material is biobased (renewable). However, starch contains moisture, and its formula (C ₆H ₁₀O ₅) n differs from that of PE (C ₂H ₄) m. On a mole basis, only 22% of this compound is organic carbon in this example. The organic carbon content is determined by the radiocarbon method according to ASTM D6866 ("Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis") [ 47]. The radiocarbon method quantifies the isotope ¹⁴C, which has a half-life of 5730 years, and allows the age determination of archeologic artefacts up to approx. 60,000 years, the quality control of food [ 48], and the determination of biobased carbon content, since fossil carbon is devoid of ¹⁴C. Alternative standards to ATSM D6866, which is used most frequently in the bioplastics industry today, are ISO 16620-2:2019 "Plastics-Biobased content-Part 2: Determination of biobased carbon content" [ 49] and EN 16640 "Bio-based products-Bio-based carbon content-Determination of the bio-based carbon content using the radiocarbon method" [ 50, 51]. Inorganic carbon would be black carbon or carbonates used as fillers in plastics, for instance.

For its certification as "OK biobased", TÜV Austria moves from ASTM D6866 to EN 16640 [ 52]. The certified products, which can be resins, intermediate products, and final articles, are classified with one to four stars to indicate the range of biobased carbon content. This gives consumers guidance and is partly linked to legal requirements, e.g., in the case of single-use plastics bags under many jurisdictions.

3.4. Bio-Attributed

The term "bio-attributed" is rather new and marketed, e.g., for PVC [ 53] and styrenics [ 54] like acrylonitrile butadiene styrene [ 55] (ABS), as well as polyoxymethylene and polyacetal [ 56] (POM). In the transition towards an increased biobased carbon content, raw materials of biological and fossil origins are mixed in the production process, and by mass-balancing the biobased carbon content is calculated and called "bio-attributed". Synonymously used terms are "bio-balanced" or "biomass-balanced". Several products bear claims like up to "x% plant-based", for instance, PET bottles with biobased ethene glycol ("Plantbottle"™), where that percentage will hardly be reached in real-life products since the material is mixed with purely or mostly fossil-based recycled PET (see ISO 14021:2016 "Environmental labels and declarations-Self-declared environmental claims" [ 57]). The Eco Mark Office of the Japan Environment Association has recently issued guidelines on "bio-attributed plastics" in its certification scheme [ 58].

4. Degradability of Plastics in General

Plastics are attacked by UV light, which can make the material brittle and easy to disintegrate under mechanical stress. UV can cleave bonds and thereby degrade the plastics, until at an endpoint, full mineralization occurs. High temperature also leads to degradation of plastics, where, e.g., mechanical recycling can create degradation products that might be toxic, and the number of "recycling rounds" can be limited as chain scissions lead to a loss of mechanical properties. Time scales of degradation of plastic products in nature can be estimated at up to hundreds of years for conventional plastics like PE, PP, and PVC. Below, several concepts of degradability are described. Thermal or thermocatalytic degradation processes aim at depolymerization (a.k.a. feedstock recycling), where ideally the monomers are won back. The concept holds promise for thermoplastics, elastomers, and thermosets. Several research projects have studied pyrolysis of plastic waste for recycling purposes. Biodegradable plastics are cleaved enzymatically in various environments, at times scales in the order of months to years, comparable to other natural organic materials. Water-soluble polymers like poly(vinyl alcohol) (PVA) cannot be considered biodegradable since the monomers will exhibit comparatively long residence times in nature. Such films, in order to be truly biodegradable, would need to be made from naturally occurring materials such as alginate.

A misconception or even prejudice towards bioplastics seems to sometimes persist with consumers, in that there is a belief that bioplastics will decompose by themselves within a few months to years while still in use, rendering them intrinsically inferior to fossil plastics in performance. This is of course not the case; the shelf life of bioplastic pellets depends on storage conditions and is, in principle, the same as for fossil plastics, as evidenced by an analysis of technical data sheets of bioplastic producers vs. fossil plastic manufacturers. When, e.g., wood, paper, or any other natural material is kept in a dry place (indoors), it does not auto-decompose either. That analogy can be applied to bioplastic products with biodegradable properties, such as PHA-based shampoo bottles stored in the bathroom-they will not disintegrate there! It is only when they come in contact with microorganisms in the environment that they start degrading. Plastic products "falling apart" only happens under UV light irradiation, in general, and with oxo-degradable materials-see the following paragraph.

4.1. Oxo-Degradable

So-called "oxo-degradable" or oxo-fragmentable plastics are an outdated concept of truly single-use plastics, where additives bring about a fragmentation of the material-typically conventional fossil and non-degradable plastics-into microplastic particles within a defined, short period of time. The material is not truly degraded (and absolutely not bio-degraded), but simply disintegrated. Such materials should neither be promoted nor used any further [ 59]. In the EU, the single-use plastics directive (SUPD, Directive EU 2019/904) [ 60] has banned oxo-degradable products since 2021. They are an example of misleading consumers and harming the environment, through the introduction of reactive microplastic particles. "Out of sight" for the naked eye clearly does not mean degraded, and we are faced with persistent microplastics in almost all ecosystems, e.g., agricultural soils and water bodies, stemming from conventional, fragmented plastics, but also such oxo-degradable materials.

4.2. (Bio)Degradable

Most (biodegradable) bioplastics are polyesters, and as such, they can be hydrolyzed by hydrolytic esterase enzymes. Under the action of microorganisms (bacteria [ 61] and fungi [ 62]), plastics can be degraded by enzymatic cleavage of the polymer chains. Natural polymers are generally biodegradable (unless they are crosslinked, like is the case in, e.g., vulcanized natural rubber). Also, several synthetic polymers can be biodegraded, e.g., the polyester poly(ε-caprolactone) (PCL). Since enzymatic activity by microorganisms is stronger in (hot and humid) compost than in soil, and even less in freshwater and the least in cold sea water, the environment plays a critical role in the rate of (bio)degradability. Depending on the availability of oxygen, aerobic and anaerobic degradation mechanisms occur. In general, when water can access the material, degradability tends to be faster [ 63]. Also, amorphous plastics degrade faster than crystalline ones, as was demonstrated for, e.g., bio-based poly(butylene adipate-co-butylene furandicarboxylate) [ 64] or for poly(lactic-co-glycolic acid) (PLGA) [ 65]. The degradability of compounds and blends is influenced by the degradability of the individual components. Thin (and foamed) products naturally degrade faster than bulky items. The presence of additives can influence biodegradability rates, too. Biodegradation under aerobic conditions differs from anaerobic processes, where CH ₄ plus CO ₂ are typically formed. In this case, the impact on the climate needs to be considered because of the emission of that CH ₄. In recent years, several test methods and standards, plus their certifications and labels, were developed to define biodegradability under certain environmental conditions, like, e.g., "marine degradability", "home compostability", or "industrial compostability". These will be summarized below.

The nova-Institute distinguishes six relevant settings for biodegradability [ 36]:

European Bioplastics (EU BP) has summarized the most relevant standards for biodegradability [ 66]. For a summary of standards and labels, see also [ 67]. Normec OWS, a large test provider of biodegradability, offers tests in various environments, e.g., according to standards ASTM D6400, ASTM D6868, ASTM D8410, AS 4736, EN 14995, EN 13432, ISO 17088, and ISO 18606, with the possibility for certificates under several jurisdictions:

Australia: ABA (Seedling);

Europe: DIN CERTO (Seedling, DIN Geprüft Industrial Compostable, DINPlus) and TÜV AUSTRIA (OK Compost, Seedling);

Japan: JBPA (GreenPla) [ 68];

TÜV Austria provides these certifications, as introduced by Vinçotte:

OK biodegradable MARINE (requirements equivalent to ASTM D 6691, 6 months);

OK biodegradable SOIL (requirements equivalent to DIN EN 13432 but not 6 months, instead 24 months);

OK biodegradable WATER (requirements equivalent to DIN EN 13432, but max. 25 °C and 56 days);

OK compost INDUSTRIAL (requirements equivalent to DIN EN 13432);

OK compost HOME (requirements equivalent to DIN EN 13432, max. 30 °C).

Apart from actual degradability, the products to be certified must be intended for use in these specific environments (not by littering). Another well-known certification body is DIN CERTCO (TÜV Rheinland).

For "industrial compostability" certification, Normec OWS demands disintegration and biodegradability as follows:

A 90% disintegration within 12 weeks;

A 90% carbon-to-CO ₂ conversion at 58 °C within 6 months.

These biodegradation tests are based on ISO 14855, ASTM D 5338, and/or EN 14046, and on ISO 16929 and/or EN 14045 for disintegration [ 68]. Ecotoxicity can be assessed according to the OECD 208 test method.

Biodegradability is a complex topic, with several partly overlapping and partly diverging standards, superimposed by blurred terminology and concepts. Not all certificates are issued by accredited organizations, and sometimes misinformation or lack of knowledge leads to inaccurate statements. With evolving legal regulations stipulating minimum requirements for biodegradability, as well as biobased carbon content, precise definitions and unambiguous tests are imperative. Below, in Table 4, several important standards are summarized with regards to biodegradability.

A bioplastic may be biodegradable, but not compostable, when its kinetics are, e.g., too slow to meet the metrics of the compostability standard (home and industrial). Some materials need the high temperature of composting (58 °C) for timely degradation, so they can be classified "industrial compostable" but not degradable in the open environment, particularly in difficult environments like marine systems, e.g., PLA.

A common logo for compostability is the "seedling". It is used to show "compostability" based on EN 13432, and it is acknowledged in Belgium, Switzerland, Germany, The Netherlands, Poland, the United Kingdom, and other countries [ 104]. It needs to be stated that even though several bioplastics meet the criteria of being compostable, they may still be partly visible at the end of a composting process, because industrial composting plants often have very short residence times of several weeks only, though even thin materials will not be mineralized that fast.

The test schemes summarized above are applied to the certification of specific polymers, as well as plastics (i.e., compounds with blend partners and/or additives) and finished items (e.g., a film or an injection-molded consumer good).

Note that commonly only 90% degradation is demanded (e.g., by EN 13432), allowing for the use of conventional, non-degradable additives.

4.3. Controlled Degradability (Enzyme Mediated)

For some products, a set lifetime is desirable. For instance, mulching films should last one season, whereas a plastic clip to protect young trees from deer would typically be needed during the first 3 years of the plants' life. The "lifetime" of a given bioplastic product can be influenced by its composition (blend of different biopolymers) and by the addition (or absence) of certain additives, e.g., enzymes for controlled degradability. Enzyme-mediated bioplastics are an emerging field of research, see, e.g., [ 105, 106].

4.4. Recyclable Plastics and the Definition of "Renewable" and "Circular"

Renewable raw materials (biomass) can be converted into renewable plastics. When plastics are recycled, they can be called "circular". Sometimes, stakeholders also use the term "renewable" or "renewed" interchangeably and synonymously with "recycled" and "recyclable" when referring to such materials. Plastics recycling is a key pillar of a circular economy, and as such, desirable. Care has to be taken about possible microplastic emissions and energy consumption, i.e., a full life cycle assessment is required to ensure that the recycling process makes sense. In general, bioplastics are recyclable. "Thermal recycling", a.k.a. waste incineration, is a misnomer when it is applied to plastics after single use, but can be useful in a cascaded concept when the energy is captured-but CO ₂ is being released to the atmosphere. For bioplastics to be truly "sustainable plastics", their end-of-life-scenarios need to be considered (see Table 5 [ 27]).

As Table 5 illustrates, bioplastics are not automatically compatible with collection and recycling schemes of conventional plastics. For instance, there is the fear that a certain fraction of bioplastics in PET could lead to deterioration of the properties in recycling, potentially making injection blow molding of recycled material unfeasible. This is a "hen and egg" problem, and solutions need to be developed for collecting, sorting, and recycling more types of plastics "post-consumer", which hardly exist today for any other plastic products than PET bottles. While many plastics are recycled in closed loops in industrial settings, e.g., the gatings (sprues) in injection molding, post-consumer plastic waste is very difficult to recycle due to the variety of products, difficulties in separation, and low volumes per grade. In as much as composite materials allow a perfect tailoring of material properties, they make recycling difficult, and we are far from full life cycle design and material standardization.

5. Discussion

Factors that limit the widespread use of bioplastics are their lack of availability, missing experience, absence of incentives/legal framework, and costs. The costs of bioplastics are higher, in general, than those of fossil plastics, leaving externalized costs aside. The cost drivers are smaller economies of scale (the biobased industry tends to operate at smaller scale than the petrochemical one), less industrial maturity (while petrochemical refineries are fully integrated, biorefineries often have a limited number of final products, with side streams that are not fully valorized), higher downstream processing costs, e.g., for intracellular PHA biopolyesters, and more costly feedstock, leading to higher costs/kg of resin. Furthermore, the density of bioplastics tends to be 20-30% higher than for polyolefins, which adds to the costs of the final parts. Some of the cost disadvantages can be overcome by mixing bioplastics with low-density biogenic side streams/waste materials, such as wood dust or fibers [ 25, 107], which results in readily biodegradable composite materials [ 108]. Moreover, bioplastics are more temperature sensitive than their fossil counterparts, which translates into a smaller processing window with typically lower productivities and thereby again higher unit production costs. However, in the mid to long run, bioplastics need to replace fossil plastics in more and more applications, which they can do already today. We see the challenges of recycling fossil plastics daily, now standing at 9% globally after decades of struggling. Even if all fossil plastics parts were recycled, there would still be the microplastic problems and the fossil carbon footprint.

A reduction of plastic consumption is the first step to be considered, and there are high-risk and unnecessary, very short-lived, single-use products, which should not just be made from biodegradable plastics but be phased out for good, e.g. some excessive packaging, e-cigarettes or cosmetic microbeads. Yet, the demand for plastic materials is there and is steadily growing; the world population is increasing and developing, pushing the desire for products. Moreover, polymer-based formulations are needed in many applications, where other biobased substitutes are neither available nor practical.

Bioplastics can help decarbonize/defossilize and circularize the plastic economy, and scientifically proven and honest claims (statements) about their properties need to be made, particularly with regard to being "biobased", "(bio)degradable", and possibly also "bio-attributed", to avoid greenwashing. The concepts, as laid out in this article, are not "black and white", but need to be regarded in a differentiated manner. The actual biodegradability of a bioplastic-made item depends not only on the polymer but also on the product (e.g., thickness, shape, crystallinity, hydrophobicity), as well as the environment with its ambient conditions, as exemplified in Figure 4 below [ 109].

The degradability is also influenced by blend partners and additives. As bioplastics are being used more widely-and this trend is expected to continue-clear definitions are important. The controlled degradability of bioplastics, e.g., by adding enzymes, is a highly interesting and promising field for future research, to develop formulations with tailored life times. The demand for such materials arises, e.g., from single-use articles in agriculture, but might possibly also contribute to rendering litter less harmful and less persistent.

The concept of renewability is clearly linked with the carbon source, where biomass is the most common raw material. Side streams and waste streams of biomass are advantageous, and other carbon sources such as non-biomass organic waste, and/or CO ₂ from point sources or captured from the atmosphere, are also feasible. Companies that work on converting gaseous feedstocks into PHA are LanzaTech (CO, CO ₂) [ 109], Mango Materials, Circe Biotechnologie, and Newlight Technologies (CH ₄). In a word, renewability is about circular carbon.

Biosynthesis has a clear definition, standing for the fact that a material has been made by plants, animals, bacteria, fungi, algae, or archaea, either naturally occurring ones or genetically modified organisms (GMOs), or by their biocatalytically active parts (enzymes).

Biodegradability refers to the enzymatic destruction (catabolism) of polymeric substances by living organisms, intra- or extracellularly, in the environment. A bioprocess with extracted enzymes, for instance, would not fall under the strict definition.

The term " degradability " includes all means, even radiation-mediated and thermal processes, which might occur in nature (abiotically) or in technical systems. Typically, when referring to the degradability of plastics or bioplastics, biodegradability is to be understood.

Finally, a biocompatible material is one that does not exert toxic or injurious effects on biological systems, a property borne by several fossil plastic materials and not necessarily being an inherent feature of biobased polymers. This concept has applications in the medical area, for instance [ 110].

The use of renewable resources can, therefore, be considered an important aspect [ 111], but it does not entirely solve the plastics crisis we are in today. We need a differentiated view on degradability/biodegradability. In this review, approx. 50 existing standards for determining biodegradability and biobased carbon content were compiled. They are partly overlapping and require specialized test institutes to perform assessments against them. Previously, attempts were made to estimate biodegradability rates based on gas evolution or differential scanning calorimetry (DSC) changes. Since biological systems are complex, tests need to be standardized and carefully be described, to ensure reproducibility. At present, there is no universal "quick test" for biodegradability, and it is likely that there will not be any such solution in the future. The selection of a test method that is relevant and most appropriate should be based on the target application and possible end-of-life scenarios of any given bioplastic product. In any case, responsible use, particularly at the end of the life cycle, and recycling should be fostered, including bioplastic materials, with biodegradation being a possible, but not the preferred solution for the products in question.

6. Conclusions

In the field of bioplastics, there are clear and unambiguous definitions of, e.g., the properties of being biobased, bio-attributed, and biodegradable, and stakeholders should use these terms in their exact meanings.

A "golden rule" in material selection is that there is seldom a clear "right" or "wrong"; instead, several materials can typically fulfil the requirements of a given applications. Fossil plastics can do the job in many cases, but they need to be managed well. Even then, they can still have detrimental effects on the environment, e.g., through microplastics' and nanoplastics' formation during the use or recycling phases, and at the end of their lifetime, typically they add to anthropogenic CO ₂ emissions. The definition of "bioplastics" should be narrowed to materials that are both biobased and-with details depending on the type of material and the application/environment-intrinsically biodegradable, as well as free from problematic additives. We should prefer additives approved for food contact materials as well as those that are biobased and biodegradable. Since micro- and nanoplastics from virtually all products can enter the food chain, more care should be taken in their formulation and development in terms of product life cycle management. Bioplastic materials meeting the definition sensu stricto are an intrinsically better solution than conventional plastics because they are less harmful when being "lost" inadvertently. In these cases, they degrade as microplastics and bulk materials in a "reasonable" time, in the order of at most years instead of centuries. Apart from the standards for biobased carbon content and biodegradability for different environments, a standard concerning transparency and selection of additives is needed, to provide full clarity throughout the value chain about the formulations. We should intensify efforts to defossilize the plastic industry, replacing conventional material with biobased and biodegradable substitutes, coupled with actions for the reduction of consumption and waste management, and we should ensure that proper definitions are applied to materials to avoid ambiguity. The feedstock for bioplastics should not be primary agricultural products, but side streams and waste streams, since high volumes are needed at full roll-out; this is relevant to the development of the bio-industry from first-generation materials to second-generation solutions.

More research will also be needed to develop advanced additives for bioplastics, not only to replace today's chemicals but also to formulate ones that are tailored to specific materials, to increase their performance. The emphasis on composites may be on fully biobased compounds, and innovative ideas for recycling including material standardization, labelling, collection, and circularity are needed. Disruptive ideas on reuse of materials will further support efforts to make material usage more sustainable. Clear definitions remain at the center of the transition from fossil to biobased and biodegradable plastics, so that we can keep the strong benefits that plastics have brought to us over the last seven decades and minimize their unwanted side effects.

AMA Style

Chicago/Turabian Style

# data[].attributes.attachment_link.description
Today, plastic materials are mostly made from fossil resources, and they are characterized by their long lifetime and pronounced persistence in the open environment. These attributes of plastics are one cause of the ubiquitous pollution we see in our environment.

# data[].attributes.attachment_link.title
Home - The webshop for Bioplastics - Bioplasticshop

# data[].attributes.attachment_link.description
Bioplasticshop is the webshop for all your bioplastic sheet material. Towards a greener future with a growing range.

# data[].attributes.attachment_link.title
The Hemp Plastic Company | Creating a Greener Future

# data[].attributes.attachment_link.description
Create a greener future with our eco-friendly, cost-effective, reliable hemp plastic materials. Contact us today to learn more.

# data[].attributes.attachment_link.readable_text
Plastic is the most prevalent type of marine debris found in our ocean and Great Lakes. Plastic debris can come in all shapes and sizes, but those that are less than five millimeters in length (or about the size of a sesame seed) are called "microplastics."

As an emerging field of study, not a lot is known about microplastics and their impacts yet. The NOAA Marine Debris Program is leading efforts within NOAA to research this topic. Standardized field methods for collecting sediment, sand, and surface-water microplastic samples have been developed and continue to undergo testing. Eventually, field and laboratory protocols will allow for global comparisons of the amount of microplastics released into the environment, which is the first step in determining the final distribution, impacts, and fate of this debris.

Microplastics come from a variety of sources, including from larger plastic debris that degrades into smaller and smaller pieces. In addition, microbeads, a type of microplastic, are very tiny pieces of manufactured polyethylene plastic that are added as exfoliants to health and beauty products, such as some cleansers and toothpastes. These tiny particles easily pass through water filtration systems and end up in the ocean and Great Lakes, posing a potential threat to aquatic life.

Microbeads are not a recent problem. According to the United Nations Environment Programme, plastic microbeads first appeared in personal care products about fifty years ago, with plastics increasingly replacing natural ingredients. As recently as 2012, this issue was still relatively unknown, with an abundance of products containing plastic microbeads on the market and not a lot of awareness on the part of consumers.

On December 28, 2015, President Obama signed the Microbead-Free Waters Act of 2015, banning plastic microbeads in cosmetics and personal care products.

Video Transcript

Plastic is everywhere. A lot of it ends up in the ocean. Most plastics in the ocean break up into very small particles. These small plastic bits are called "microplastics." Other plastics are intentionally designed to be small. They're called microbeads and are used in many health and beauty products. They pass unchanged through waterways into the ocean. Aquatic life and birds can mistake microplastics for food. Research is being conducted. But there's still much we don't know. In 2015, the U.S. banned the use of microbeads. But microplastics are still a huge problem. You can help keep plastic out of the ocean. Remember: Reduce. Reuse. Recycle.

# data[].attributes.attachment_link.description
Microplastics are small plastic pieces less than five millimeters long which can be harmful to our ocean and aquatic life.

# data[].attributes.attachment_link.title
What are Microplastics and Microfibers? - Ocean Conservancy

# data[].attributes.attachment_link.description
Despite their small size, microplastics and microfibers present a huge problem for ocean, wildlife and human health. Read for more.

# data[].attributes.attachment_link.readable_text
Tiny particles of plastic have been found everywhere - from the deepest place on the planet, the Mariana Trench, to the top of Mount Everest. And now more and more studies are finding that microplastics, defined as plastic pieces less than 5 millimeters across, are also in our bodies.

"What we are looking at is the biggest oil spill ever," says Maria Westerbos, founder of the Plastic Soup Foundation, an Amsterdam-based nonprofit advocacy organization that works to reduce plastic pollution around the world. Nearly all plastics are made from fossil fuel sources. And microplastics are "everywhere," she adds, "even in our bodies."

In recent years, microplastics have been documented in all parts of the human lung, in maternal and fetal placental tissues, in human breast milk and in human blood. Microplastics scientist Heather Leslie, formerly of Vrije Universiteit Amsterdam, and colleagues found microplastics in blood samples from 17 of 22 healthy adult volunteers in the Netherlands. The finding, published last year in Environment International, confirms what many scientists have long suspected: These tiny bits can get absorbed into the human bloodstream.

"We went from expecting plastic particles to be absorbable and present in the human bloodstream to knowing that they are," Leslie says.

Microplastics in the blood

Microplastic particles were detected in blood samples from 17 of 22 healthy adult volunteers in the Netherlands. The types of polymer present varied across the group - as did the concentrations. Donors 11, 12 and 13 contributed two samples, both with microplastics. For many others (starred), one sample had microplastics and a second did not.

Concentration of microplastics in human blood samples

T. TIBBITTS

The findings aren't entirely surprising; plastics are all around us. Durable, versatile and cheap to manufacture, they are in our clothes, cosmetics, electronics, tires, packaging and so many more items of daily use. And the types of plastic materials on the market continues to increase. "There were around 3,000 [plastic materials] when I started researching microplastics over a decade ago," Leslie says. "Now there are over 9,600. That's a huge number, each with its own chemical makeup and potential toxicity."

Though durable, plastics do degrade, by weathering from water, wind, sunlight or heat - as in ocean environments or in landfills - or by friction, in the case of car tires, which releases plastic particles along roadways during motion and braking.

In addition to studying microplastic particles, researchers are also trying to get a handle on nanoplastics, particles which are less than 1 micrometer in length. "The large plastic objects in the environment will break down into micro- and nanoplastics, constantly raising particle numbers," says toxicologist Dick Vethaak of the Institute for Risk Assessment Sciences at Utrecht University in the Netherlands, who collaborated with Leslie on the study finding microplastics in human blood.

Nearly two decades ago, marine biologists began drawing attention to the accumulation of microplastics in the ocean and their potential to interfere with organism and ecosystem health ( SN: 2/20/16, p. 20). But only in recent years have scientists started focusing on microplastics in people's food and drinking water - as well as in indoor air.

Plastic particles are also intentionally added to cosmetics like lipstick, lip gloss and eye makeup to improve their feel and finish, and to personal care products, such as face scrubs, toothpastes and shower gels, for the cleansing and exfoliating properties. When washed off, these microplastics enter the sewage system. They can end up in the sewage sludge from wastewater treatment plants, which is used to fertilize agricultural lands, or even in treated water released into waterways.

What if any damage microplastics may do when they get into our bodies is not clear, but a growing community of researchers investigating these questions thinks there is reason for concern. Inhaled particles might irritate and damage the lungs, akin to the damage caused by other particulate matter. And although the composition of plastic particles varies, some contain chemicals that are known to interfere with the body's hormones.

Currently there are huge knowledge gaps in our understanding of how these particles are processed by the human body.

How do microplastics get into our bodies?

Research points to two main entry routes into the human body: We swallow them and we breathe them in.

Evidence is growing that our food and water is contaminated with microplastics. A study in Italy, reported in 2020, found microplastics in everyday fruits and vegetables. Wheat and lettuce plants have been observed taking up microplastic particles in the lab; uptake from soil containing the particles is probably how they get into our produce in the first place.

Sewage sludge can contain microplastics not only from personal care products, but also from washing machines. One study looking at sludge from a wastewater treatment plant in southwest England found that if all the treated sludge produced there were used to fertilize soils, a volume of microplastic particles equivalent to what is found in more than 20,000 plastic credit cards could potentially be released into the environment each month.

On top of that, fertilizers are coated with plastic for controlled release, plastic mulch film is used as a protective layer for crops and water containing microplastics is used for irrigation, says Sophie Vonk, a researcher at the Plastic Soup Foundation.

"Agricultural fields in Europe and North America are estimated to receive far higher quantities of microplastics than global oceans," Vonk says.

Microplastics in everyday produce

Fruits and vegetables purchased at local markets in Catania, Italy, showed wide variability in the numbers of microplastic particles present. The research highlights the need for more studies on the sources of microplastic exposure.

Microplastic particles detected in produce samples

T. TIBBITTS T. TIBBITTS

A recent pilot study commissioned by the Plastic Soup Foundation found microplastics in all blood samples collected from pigs and cows on Dutch farms, showing livestock are capable of absorbing some of the plastic particles from their feed, water or air. Of the beef and pork samples collected from farms and supermarkets as part of the same study, 75 percent showed the presence of microplastics. Multiple studies document that microplastic particles are also in fish muscle, not just the gut, and so are likely to be consumed when people eat seafood.

Microplastics are in our drinking water, whether it's from the tap or bottled. The particles may enter the water at the source, during treatment and distribution, or, in the case of bottled water, from its packaging.

Results from studies attempting to quantify levels of human ingestion vary dramatically, but they suggest people might be consuming on the order of tens of thousands of microplastic particles per person per year. These estimates may change as more data come in, and they will likely vary depending on people's diets and where they live. Plus, it is not yet clear how these particles are absorbed, distributed, metabolized and excreted by the human body, and if not excreted immediately, how long they might stick around.

Babies might face particularly high exposures. A small study of six infants and 10 adults found that the infants had more microplastic particles in their feces than the adults did. Research suggests microplastics can enter the fetus via the placenta, and babies could also ingest the particles via breast milk. The use of plastic feeding bottles and teething toys adds to children's microplastics exposure.

Microplastic particles are also floating in the air. Research conducted in Paris to document microplastic levels in indoor air found concentrations ranging from three to 15 particles per cubic meter of air. Outdoor concentrations were much lower.

Airborne particles may turn out to be more of a concern than those in food. One study reported in 2018 compared the amount of microplastics present within mussels harvested off Scotland's coasts with the amount of microplastics present in indoor air. Exposure to microplastic fibers from the air during the meal was far higher than the risk of ingesting microplastics from the mussels themselves.

Extrapolating from this research, immunologist Nienke Vrisekoop of the University Medical Center Utrecht says, "If I keep a piece of fish on the table for an hour, it has probably gathered more microplastics from the ambient air than it has from the ocean."

Where in the air?

Concentrations of microplastics and nanoplastics in the air likely vary with location. Researchers are interested in studying various settings to better understand human exposure and risk including traffic lights, indoor sports stadiums, textile factories and living rooms.

What's more, a study of human lung tissue reported last year offers solid evidence that we are breathing in plastic particles. Microplastics showed up in 11 of 13 samples, including those from the upper, middle and lower lobes, researchers in England reported.

Perhaps good news: Microplastics seem unable to penetrate the skin. "The epidermis holds off quite a lot of stuff from the outside world, including [nano]particles," Leslie says. "Particles can go deep into your skin, but so far we haven't observed them passing the barrier, unless the skin is damaged."

What do we know about the potential health risks?

Studies in mice suggest microplastics are not benign. Research in these test animals shows that lab exposure to microplastics can disrupt the gut microbiome, lead to inflammation, lower sperm quality and testosterone levels, and negatively affect learning and memory.

But some of these studies used concentrations that may not be relevant to real-world scenarios. Studies on the health effects of exposure in humans are just getting under way, so it could be years before scientists understand the actual impact in people.

Immunologist Barbro Melgert of the University of Groningen in the Netherlands has studied the effects of nylon microfibers on human tissue grown to resemble lungs. Exposure to nylon fibers reduced both the number and size of airways that formed in these tissues by 67 percent and 50 percent, respectively. "We found that the cause was not the microfibers themselves but rather the chemicals released from them," Melgert says.

"Microplastics could be considered a form of air pollution," she says. "We know air pollution particles tend to induce stress in our lungs, and it will probably be the same for microplastics."

Vrisekoop is studying how the human immune system responds to microplastics. Her unpublished lab experiments suggest immune cells don't recognize microplastic particles unless they have blood proteins, viruses, bacteria or other contaminants attached. But it is likely that such bits will attach to microplastic particles out in the environment and inside the body.

"If the microplastics are not clean ... the immune cells [engulf] the particle and die faster because of it," Vrisekoop says. "More immune cells then rush in." This marks the start of an immune response to the particle, which could potentially trigger a strong inflammatory reaction or possibly aggravate existing inflammatory diseases of the lungs or gastrointestinal tract.

Some of the chemicals added to make plastic suitable for particular uses are also known to cause problems for humans: Bisphenol A, or BPA, is used to harden plastic and is a known endocrine disruptor that has been linked to developmental effects in children and problems with reproductive systems and metabolism in adults ( SN: 7/18/09, p. 5). Phthalates, used to make plastic soft and flexible, are associated with adverse effects on fetal development and reproductive problems in adults along with insulin resistance and obesity. And flame retardants that make electronics less flammable are associated with endocrine, reproductive and behavioral effects.

"Some of these chemical products that I worked on in the past [like the polybrominated diphenyl ethers used as flame retardants] have been phased out or are prohibited to use in new products now [in the European Union and the United States] because of their neurotoxic or disrupting effects," Leslie says.

Concerning chemicals

Bits of plastic floating in the world's air and water contain chemicals that may pose risks to human health. A 2021 study identified more than 2,400 chemicals of potential concern found in plastics or used in their processing. Here are a few of the most worrisome.

Short-chain chlorinated paraffins are used as lubricants, flame retardants and plasticizers. They can cause cancer in lab rodents, but the mechanisms may not be relevant for human health.

The chlorinated compound mirex was once used as a flame retardant and can persist in the environment. It's suspected of being a human carcinogen and may affect fertility.

2,4,6-Tri-tert-butylphenol is an antioxidant and ultraviolet stabilizer, added to plastics to prevent degradation. There's evidence that it causes liver damage in lab animals with prolonged or repeated exposure.

Benzo(a)pyrene is a polyaromatic hydrocarbon that can be released when organic matter such as coal or wood burns. It is also produced in grilled meats. It has been shown to cause cancer, damage fertility and affect development in lab animals.

Dibutyl phthalate is a plasticizer that is known to cause endocrine disruption, may interfere with male fertility and has been shown to affect fetal development in lab animals.

Tetrabromobisphenol-A is a flame retardant that can cause cancer in lab animals and may be an endocrine disruptor. It is chemically related to bisphenol A, which has been linked to developmental effects in children.

What are the open questions?

The first step in determining the risk of microplastics to human health is to better understand and quantify human exposure. Polyrisk - one of five large-scale research projects under CUSP, a multidisciplinary group of researchers and experts from 75 organizations across 21 European countries studying micro- and nanoplastics - is doing exactly that.

Immunotoxicologist Raymond Pieters, of the Institute for Risk Assessment Sciences at Utrecht University and coordinator of Polyrisk, and colleagues are studying people's inhalation exposure in a number of real-life scenarios: near a traffic light, for example, where cars are likely to be braking, versus a highway, where vehicles are continuously moving. Other scenarios under study include an indoor sports stadium, as well as occupational scenarios like the textile and rubber industry.

Melgert wants to know how much microplastic is in our houses, what the particle sizes are and how much we breathe in. "There are very few studies looking at indoor levels [of microplastics]," she says. "We all have stuff in our houses - carpets, insulation made of plastic materials, curtains, clothes - that all give off fibers."

Vethaak, who co-coordinates MOMENTUM, a consortium of 27 research and industry partners from the Netherlands and seven other countries studying microplastics' potential effects on human health, is quick to point out that "any measurement of the degree of exposure to plastic particles is likely an underestimation." In addition to research on the impact of microplastics, the group is also looking at nanoplastics. Studying and analyzing these smallest of plastics in the environment and in our bodies is extremely challenging. "The analytical tools and techniques required for this are still being developed," Vethaak says.

Vethaak also wants to understand whether microplastic particles coated with bacteria and viruses found in the environment could spread these pathogens and increase infection rates in people. Studies have suggested that microplastics in the ocean can serve as safe havens for germs.

Alongside knowing people's level of exposure to microplastics, the second big question scientists want to understand is what if any level of real-world exposure is harmful. "This work is confounded by the multitude of different plastic particle types, given their variations in size, shape and chemical composition, which can affect uptake and toxicity," Leslie says. "In the case of microplastics, it will take several more years to determine what the threshold dose for toxicity is."

Several countries have banned the use of microbeads in specific categories of products, including rinse-off cosmetics and toothpastes. But there are no regulations or policies anywhere in the world that address the release or concentrations of other microplastics - and there are very few consistent monitoring efforts. California has recently taken a step toward monitoring by approving the world's first requirements for testing microplastics in drinking water sources. The testing will happen over the next several years.

Pieters is very pragmatic in his outlook: "We know 'a' and 'b,'" he says. "So we can expect 'c,' and 'c' would [imply] a risk for human health."

He is inclined to find ways to protect people now even if there is limited or uncertain scientific knowledge. "Why not take a stand for the precautionary principle?" he asks.

For people who want to follow Pieters' lead, there are ways to reduce exposure.

"Ventilate, ventilate, ventilate," Melgert says. She recommends not only proper ventilation, including opening your windows at home, but also regular vacuum cleaning and air purification. That can remove dust, which often contains microplastics, from surfaces and the air.

Consumers can also choose to avoid cosmetics and personal care products containing microbeads. Buying clothes made from natural fabrics like cotton, linen and hemp, instead of from synthetic materials like acrylic and polyester, helps reduce the shedding of microplastics during wear and during the washing process.

Specialized microplastics-removal devices, including laundry balls, laundry bags and filters that attach to washing machines, are designed to reduce the number of microfibers making it into waterways.

Vethaak recommends not heating plastic containers in the microwave, even if they claim to be food grade, and not leaving plastic water bottles in the sun.

Perhaps the biggest thing people can do is rely on plastics less. Reducing overall consumption will reduce plastic pollution, and so reduce microplastics sloughing into the air and water.

Leslie recommends functional substitution: "Before you purchase something, think if you really need it, and if it needs to be plastic."

Westerbos remains hopeful that researchers and scientists from around the world can come together to find a solution. "We need all the brainpower we have to connect and work together to find a substitute to plastic that is not toxic and doesn't last [in the environment] as long as plastic does," she says.

Questions or comments on this article? E-mail us at feedback@sciencenews.org | Reprints FAQ

A version of this article appears in the March 25, 2023 issue of Science News.

Citations

I. van der Veen et al. Plastic Particles in Livestock Feed, Milk, Meat and Blood.

M. Atamanalp et al. Microplastics in Tissues (Brain, Gill, Muscle and Gastrointestinal) of Mullus barbatus and Alosa immaculata. Archives of Environmental Contamination and Toxicology. September 20, 2021, p. 460-469. doi: 10.1007/s00244-021-00885-5.

B. Oßmann. Microplastics in drinking water? Present state of knowledge and open questions. Current Opinion in Food Science. Vol. 41, October 2021, p. 44-51. doi: 10.1016/j.cofs.2021.02.011.

A. Ragusa et al. Plasticenta: First evidence of microplastics in human placenta. Environment International. Vol. 146, January 2021. doi: 10.1016/j.envint.2020.106274.

J. Gasperi et al. First overview of microplastics in indoor and outdoor air. 15th EuCheMS International Conference on Chemistry and the Environment, Leipzig (Germany), September 2015.

A.I. Catarino et al. Low levels of microplastics (MP) in wild mussels indicate that MP ingestion by humans is minimal compared to exposure via household fibres fallout during a meal. Environmental Pollution. Vol. 237, June 2018, p. 675-684. doi: 10.1016/j.envpol.2018.02.069.

L. C. Jenner et al. Detection of microplastics in human lung tissue using μFTIR spectroscopy. Science of the Total Environment. Vol. 831, July 20, 2022. doi: 10.1016/j.scitotenv.2022.154907.

This article was supported by readers like you.

Our mission is to provide accurate, engaging news of science to the public. That mission has never been more important than it is today.

As a nonprofit news organization, we cannot do it without you.

Your support enables us to keep our content free and accessible to the next generation of scientists and engineers. Invest in quality science journalism by donating today.

# data[].attributes.attachment_link.title
Microplastics are in our bodies. Here's why we don't know the health risks

# data[].attributes.attachment_link.description
Tiny particles of plastic have been found everywhere - from the deepest place on the planet, the Mariana Trench, to the top of Mount Everest. And now more and more studies are finding that microplastics, defined as plastic pieces less than 5 millimeters across, are also in our bodies.

# data[].attributes.attachment_link.readable_text
Fibers, flakes, spheres, foams: every day we eat, drink, and inhale tiny bits of plastic. What happens once they enter our bodies is a question that worries a growing number of scientists and clinicians.

The study of whether and how microplastics - particles smaller than 5 millimeters that slough off plastic as it degrades - pose threats to human health is still in its infancy. As the World Health Organization underscored in a 2022 report, current technologies don't yet enable researchers to quantify population-level microplastics exposures or gauge what proportion of those particles stay in our bodies. However, microplastics' ubiquity in the environment, combined with preliminary findings from human cell and animal studies over the past decade, have led to urgent calls for more research and regulation.

"There are so many unknowns," says Bernardo Lemos, an adjunct professor of environmental epigenetics at the Harvard T.H. Chan School of Public Health, "but we are seeing more data that suggest microplastics affect human biology."

Understanding what these particles might do to our genes, cells, and organs is of increasing importance as changing weather patterns sweep microplastics into more of Earth's lands, waters, and air.

Fortunately, according to Eşref Demir, an HMS visiting professor of dermatology at Massachusetts General Hospital, and Fatma Turna Demir, an HMS research fellow in neurosurgery at Mass General, the medical community is becoming more knowledgeable about plastic particle pollution and the diseases and syndromes that may be linked to it.

Where they are

We encounter microplastics everywhere: from trash, dust, fabrics, cosmetics, cleaning products, rain, seafood, produce, table salt, and more.

Little wonder that microplastics have been detected throughout the human body, including in the blood, saliva, liver, kidneys, and placenta. Investigators are probing how they get into other organs and tissues from the lungs and gastrointestinal tract. Microplastics smaller than 1 micrometer, known as nanoplastics, worry researchers the most because they can infiltrate cells.

Using a model of human intestinal lining, a team led by Philip Demokritou, director of the Environmental Health Nanoscience Laboratory at the Harvard Chan School, found that nanoplastics can enter cells in two different ways and even get into cell nuclei.

Lessons from the field of environmental toxicology raise flags about cancer and reproductive issues. Studies in cell cultures, marine wildlife, and animal models indicate that microplastics can cause oxidative damage, DNA damage, and changes in gene activity, known risks for cancer development. Microplastics have been found in human breast milk and meconium, an infant's first stool. A few studies in mice have found reproductive effects such as reduced sperm count and quality, ovarian scarring, and metabolic disorders in offspring.

Microplastics' physical properties are one source of potential hazards. Some marine organisms seem to be eating more microplastics and fewer nutrients, which can reverberate up the food chain. In humans, researchers point to illnesses caused by particulate air pollution, which contains microplastics, and by workplace exposure to plastic dust.

Other threats arise from chemicals in and on microplastic particles, including plastic components - such as BPA, phthalates, and heavy metals - that are known or suspected to cause disruption to nervous, reproductive, and other systems.

Although the variety of microplastics and the difficulty of estimating accumulation in human tissues make it challenging to pin down risks, findings in models show inflammation, cell death, lung and liver effects, changes in the gut microbiome, and altered lipid and hormone metabolism.

Mounting evidence suggests that microplastics magnify the potency of other toxicant exposures, such as cadmium, as Demir and Turna Demir have confirmed in fruit flies and Lemos has confirmed in mice and fruit flies. Others are chasing down hints that microplastics can carry antibiotic-resistant bacteria and other pathogens on their surfaces and into our bodies.

What to do?

While research develops, solutions beckon. Scientists are exploring plastic-eating microorganisms and plastic alternatives. Individuals can advocate for reduced plastic manufacturing and more recycling, and physicians can push for greater sustainability in hospitals and clinics.

"We want to get rid of terrible plastics in our transdisciplinary projects, our hospitals, and our patients' lives," wrote Demir and Turna Demir in a joint email. "Find strategies to segregate and recycle plastic medical waste. Review the use of plastic, especially single-use plastics, and synthetic textile products."

As plastic waste skyrockets, threats to human health may escalate, according to a May 2021 Nature news article. The production and destruction of plastics produces particles and gases that contribute to climate change, and plastic left to break down in the environment releases greenhouse gases. Studies suggest that microplastics disrupt marine microorganisms' globally crucial roles of sequestering carbon dioxide and producing oxygen. These deficits further jeopardize our health and that of our planet.
Stephanie Dutchen is the manager of feature content and multimedia in the Office of Communications and External Relations at HMS. Image: Bozidarka Jaglicic/iStock/Getty Images

# data[].attributes.attachment_link.description
The tiny particles are even in our bodies. What might this mean for our health?

# data[].attributes.attachment_link.title
The impact of microplastics on female reproduction and early life

# data[].attributes.attachment_link.description
Plastic pollution in our environment is one of the most important global health concerns right now. Micro- and nanoplastics (MNPs) are taken up by both humans and animals, mainly via food and water, and can pass important epithelial barriers.…

# data[].attributes.attachment_link.title
What’s lurking in your body? Mayo probes health risks of tiny plastic particles - Mayo Clinic News Network

# data[].attributes.attachment_link.description
Researchers at the Mayo Clinic Center for Individualized Medicine are investigating health risks linked to tiny plastic particles.

# data[].attributes.attachment_link.description
Learn more about these tiny pieces of plastic that can be found throughout the ocean.

# data[].attributes.attachment_link.readable_text
The millions of tons of plastic swirling around the world's oceans have garnered a lot of media attention recently. But plastic pollution arguably poses a bigger threat to the plants and animals - including humans - who are based on land.

Very little of the plastic we discard every day is recycled or incinerated in waste-to-energy facilities. Much of it ends up in landfills, where it may take up to 1,000 years to degrade, leaching potentially toxic substances into the soil and water.

Researchers in Germany are warning that the impact of microplastics in soils, sediments and freshwater could have a long-term negative effect on such ecosystems. They say terrestrial microplastic pollution is much higher than marine microplastic pollution - estimated at four to 23 times higher, depending on the environment.

On the left: Artificial turf football field with ground tyre rubber used for cushioning. On the right: Microplastics from the same field, washed away by rain, and found close to a stream, Kristiansand, Norway. Photo: Soleincitta

The researchers concludethat, although little research has been carried out in this area, the results to date are concerning: fragments of plastic are present practically all over the world and can trigger many kinds of adverse effects.

The study estimates that one third of all plastic waste ends up in soils or freshwater. Most of this plastic disintegrates into particles smaller than five millimetres, known as microplastics, and these break down further into nanoparticles (less than 0.1 micrometre in size). The problem is that these particles are entering the food chain.
Sewage
Sewage is an important factor in the distribution of microplastics. In fact, between 80 per cent and 90 per cent of the plastic particles contained in sewage, such as from garment fibres, persist in the sludge, says the study. Sewage sludge is often applied to fields as fertilizer, meaning that several thousand tons of microplastics end up in our soils each year. Microplastics can even be found in tap water.

Moreover, the surfaces of tiny fragments of plastic may carry disease-causing organisms and act as a vector for diseases in the environment. Microplastics can also interact with soil fauna, affecting their health and soil functions. "Earthworms, for example, make their burrows differently when microplastics are present in the soil, affecting the earthworm's fitness and the soil condition," says an article in Science Daily about the research.
Toxic effects
In 2020, the first-ever field study to explore how the presence of microplastics can affect soil fauna was published in the Proceedings of the Royal Society. The paper notes that terrestrial microplastic pollution has led to the decrease of species that live below the surface, such as mites, larvae and other tiny creatures that maintain the fertility of the land.

Chlorinated plastic can release harmful chemicals into the surrounding soil, which can then seep into groundwater or other surrounding water sources, and also the ecosystem. This can cause a range of potentially harmful effects on the species that drink the water.

Shovel excavator spreading sewage sludge on a field. Photo: Flickr / SuSanA Secretariat

Generally speaking, when plastic particles break down, they gain new physical and chemical properties, increasing the risk that they will have a toxic effect on organisms. And the larger the number of potentially affected species and ecological functions, the more likely it is that toxic effects will occur.

Chemical effects are especially problematic at the degradation stage. Additives such as phthalates and Bisphenol A (widely known as BPA) leach out of plastic particles. These additives are known for their hormonal effects and can disrupt the hormone system of vertebrates and invertebrates alike. In addition, nano-sized particles may cause inflammation, traverse cellular barriers, and even cross highly selective membranes such as the blood-brain barrier or the placenta. Within the cell, they can trigger changes in gene expression and biochemical reactions, among other things.

The long-term effects of these changes have not yet been sufficiently explored. "However, it has already been shown that when passing the blood-brain barrier nanoplastics have a behaviour-changing effect in fish," according to the Leibnitz Institute of Freshwater Ecology and Inland Fisheries.
How do microplastics get into our water?
One of the main sources is our clothing. Minuscule fibres of acrylic, nylon, spandex, and polyester are shed each time we wash our clothes and are carried off to wastewater treatment plants or discharged to the open environment.

According to a recent study cited by Water World in 2016, more than 700,000 microscopic plastic fibres could be released into the environment during each cycle of a washing machine. This has not yet been studied in the case of handwashing, which is more common in developing counties, but the effects could be significant there as well.

Another study commissioned in the same year by clothing company Patagonia and conducted by researchers at the University of California, Santa Barbara, found that washing a single synthetic jacket just once released an average of 1.7 grams of microfibres.

In 2019, it was estimated that 1.5 million trillion microfibers were present in the oceans around the world.
Microbeads
Microbeads are solid plastic particles that typically range from 10 micrometers (0.00039 inches) up to 1 millimeter (0.039 inches).

Numerous countries around the world have introduced legislation to ban the manufacture of cosmetics and personal care products containing microbeads. Such laws have already been passed in Canada, Ireland, the Netherlands and the United Kingdom.

Microbeads are solid plastic particles that typically range from 10 micrometers up to 1 millimeter. Photo: Wikimedia

In May 2018, the Food and Agriculture Organization (FAO) and its Global Soil Partnership, the World Health Organization, the Secretariats of the Basel, Rotterdam and Stockholm Convention, and the United Nations Environment Programme (UNEP) organized the Global Symposium on Soil Pollution (GSOP18) to bring together science and policy to understand the status, causes, impacts and solutions to soil pollution. The outcome document of the symposium, ' Be the solution to soil pollution' paved the way to the implementation of a coordinated set of actions to # StopSoilPollution.

In 2021, FAO and UNEP teamed up again to launch the Global Assessment of Soil Pollution, which details the risks and impacts of soil pollution on human health, the environment and food security.

For further information: Birguy.Lamizana@un.org

# data[].attributes.attachment_link.title
Plastic planet: How tiny plastic particles are polluting our soil

# data[].attributes.attachment_link.description
Much more research needs to be done to understand the impacts of microplastic pollution on land.

# data[].attributes.attachment_link.title
Environmental Impacts of Microplastics and Nanoplastics: A Current Overview

# data[].attributes.attachment_link.description
The increasing distribution of miniaturized plastic particles, viz. microplastics (100 nm–5 mm) and nanoplastics (less than 100 nm), across the various ecosystems is currently a subject of major environmental concern. Exacerbating these concerns is…

# data[].attributes.attachment_link.title
Advantages and Disadvantages of Bioplastics Production from Starch and Lignocellulosic Components

# data[].attributes.attachment_link.description
The accumulation of plastic wastes in different environments has become a topic of major concern over the past decades; therefore, technologies and strategies aimed at mitigating the environmental impacts of petroleum products have gained worldwide…

# data[].attributes.attachment_link.title
Bioplastics: Innovation for Green Transition

# data[].attributes.attachment_link.description
Bioplastics are one of the possible alternative solutions to the polymers of petrochemical origins. Bioplastics have several advantages over traditional plastics in terms of low carbon footprint, energy efficiency, biodegradability and versatility.…

# data[].attributes.attachment_link.readable_text
The main reason why plastic is becoming so problematic is that it is immensely useful. We are using it in almost every sphere of life. In fact, no matter wherever you look, it is almost impossible to not find plastic there. Now more than ever we are facing the dilemma. Should we stop using plastic and curb our economic growth or should we keep on using it and destroy the environment? In this debate, companies are coming up with alternatives to plastic. Out of all these alternatives, bioplastic is standing in the front. If it works, in future years, it might take the place of plastic. However, with it too, there are many complications.

The Good, the bad and the ugly of Bioplastics

With the ever-increasing awareness of the environment as well as the health hazards of oil-derived plastics, the global industry is taking into consideration the plant based alternatives (aka Bioplastics). Bioplastics consist of renewable materials like starch from corn, potato etc., soy protein, cellulose and lactic acid. Unlike synthetic plastics, bioplastics are non toxic. Moreover, one can easily decompose most of them to form water, biomass and little amount of carbon dioxide. Biofuels are not new. They have been there for years. However, owing to the lack of popularity of plastic, they are becoming popular for the commercial applications over the last decade.

The other factors to this include environmental problems and the mounting cost of oil. Bioplastics have a number of advantages over their synthetic counterparts. On the other hand, there are some concerns too. Let's take a detailed look at the pros and cons of the 'sustainable' bioplastics.

The good:

Bioplastics are perceived to be environmental friendly and hence, the range of their applications is expanding. These biodegradable plastics are nowadays being extensively used to make shopping bags, packaging, cutlery, mulch film, food service products, fishing nets and many more such products. This polymer is emerging in markets because this material is non toxic and eco friendly. Biomass including trees plants and other organic materials, all of which are renewable, are required to manufacture bioplastics.

The biodegradable plastics are further decomposable and if not recycled, it gets absorbed in the earth in very less time. The break down process is also faster, giving off biomass and water, and minimum amount of harmful carbon emissions. Their manufacturing process does not cause any damage to the environment as there is little emission of greenhouse gases and the manufacturing process requires around half of the energy required to manufacture their non biodegradable counterparts.

Can this be better?

Utilizing biodegradable plastics have various ecological benefits. Without adding much of harmful content to the atmosphere, they are made up in a much cleaner way than the traditional plastics. In contrast to conventional plastics, which make use of fossil fuel i.e. petroleum, the bioplastics do not depend on these non renewable oils for their production. After being discarded these bioplastics are molded into water and organic content that mingles in the soil and make it healthier. The future seems great and promising for the bioplastics if few of the things, including the cost effectiveness and the disposal issues, could be addressed in a proper way.

The bad:

Though these plant-based plastics may apparently be green for the eco-aware people, as they depend on biomass for their production, but the fossil fuels required to provide energy for their manufacturing, make them not so green. These materials can be composted only inside the composting industries and not in homes. The accessibility to these industries can be a problem as such facilities are limited in the countries.

Bioplastics are made out of biomass that has to be cultivated. Genetically modified corn and soybean, which are mainly used as biomass, have to be fed with toxic pesticides thus contributing to environmental as well as soil pollution. Although, the Oxo-Biodegradable plastic bags that consist of small bits of harmful metals like manganese, cobalt and iron are compostable, but the metal leftover may pose danger to the environment. Moreover, the plastic bags made of bioplastics are not as strong as the regular plastic bags and also have problems with moisture, limiting the use of bioplastics

Can this be avoided?

There are various methods of producing bioplastics. That is why the compostable plastics vary in their capabilities and properties. Almost all of these make use of renewable and organic components for manufacturing of biodegradable plastics. Moreover, the bioplastics market is quite small as of now. Therefore, the issues remain with the disposal, as the composting facilities are not everywhere. Scientists are trying to find out various methods to make these bioplastics more cost effective as well as eco friendly.

The ugly:

Bioplastics are required to be separated from the other plastics before they are recycled. These plastics, if are not chucked out in a proper way, will contribute more rubbish in the waste streams. The inappropriate means of decomposing will entail toxins like methane, carbon dioxide and ozone depleting chemicals to the atmosphere. The eco toxicity will also be contributed by carcinogens, acidifications etc., which mostly come from the pesticides and fertilizers used for processing bioplastics.

Why are we so critical?

With the rising environmental concerns and the shrinking oil supply, bioplastics are being considered as a good alternative. Although, the bioplastics are not being used on a large scale owing to the costs associated and a few downsides, they do hold a promising future. Keeping cons aside, it is without doubt a green option to choose bioplastics over regular petroleum based synthetic plastics.

The bottomline

With the ongoing advancements in the bioplastics industry, there seems to be a great potential for improvement. The disposal issues, infrastructure problem and the lack of production facilities or the composting centers could be the major problem for the growth of the bioplastics market. Still, we can't deny the fact that the bioplastics are here to stay and its share is going to increase in the plastics market in the coming years.

6 Major Trends in Bioplastics

1. Waste chicken feathers converted into bioplastic:

Dr. Yiqi Yang, from the Institute of Agriculture and Natural Resources, at the University of Nebraska-Lincoln, have ingeniously conceived of a new type of bioplastic made out of waste chicken feathers. Now the advantage of this conception is the relative abundance of one of its components i.e. feathers, as proven by this statistical figure - annually, United States alone generates more than 3 billion pounds (appox. 1.36 billion kg) of chicken feathers. The bulk part of it is either processed into animal feed or simply discarded.

2. 100 percent plant-based 'edible' plastic:

Melbourne based bio-plastic manufacturer Plantic has come up with a remarkable and rather convenient conception in the form of fully plant based bio-plastics, which can easily degrade in water in just about 20 seconds! The plastics are composed from starch (available from corn); while their paints are also totally non-toxic and derived from natural plant materials (which actually make them pretty much edible). The only downside to this crucial technology can be the presence of humidity and moisture in the air.

3. Making bio-plastics from potatoes!

Plastic from potatoes is set to be the new rage in the 'green' market, according to a report put forth by University of Maine's Margaret Chase Smith Policy Center. Composed from the root portion of the potatoes, such plant based plastics can also prove to economically viable in the long run, as they can be acquired as a by-product of the mushrooming potato chips industry. Moreover, they can be used in various applications, like carpeting, upholstery fabric and recyclable plastic bottles.

4. Growing Plastic in Grass:

Massachusetts-based Biotech Company, Metabolix, has conceived the naturalistic way to manufacture Polyhydroxybutyrate (PHA), a form of bio-plastic. This unique and rather advanced technology literally calls for growing plastics out of leaves of perennial plants such as switch grass. Dubbed as Mirel, such plastics can be used for a plethora of products like credit cards, plastic containers and even vehicle components.

5. Researchers engineer genes of plants to grow raw materials for green plastic:

Extraordinary situations call for extraordinary measures, and that is exactly what researchers from Brookhaven National Laboratory and Dow Agro-Sciences have come up with, in the face of plastic pollution. They have successfully managed to bio-engineer a relative of cabbage with high content of omega-7 fatty acid. Omega-7 fatty acid is one the major components of plastic, and with the naturalistic solution of 'cultivating' it, genetically modified seeds can be now be used as a renewable source of chemicals. That in turn can then be used to make greener plastics in the long run.

6. New plant fatty acid-derived plastic can be broken down to diesel-like liquid fuel:

New York's Polytechnic University researchers led by Professor Richard Gross have contrived a new type of advanced fuel-latent plastic. It has been derived from the components comprising the fatty acids of plants. And the crucial part is that it can be broken down into a diesel-like liquid fuel, which can have significant industrial uses, especially in relation to generators and transportation.

The benefits:

There are a myriad of benefits that can be associated with bio-plastics, namely its convenient virtue of biodegradability (the majority of bio-plastics are biodegradable). The positive quotient on environment, especially in relation to the naturalistic compositions of bio-plastics can make a significant contribution to the state of our overall sustainability. Studies have showed that bio-plastics represent a whopping 42 percent reduction in carbon footprint, because it relies much less on fossil fuel as a carbon source and also introduces fewer, net-new greenhouse emissions if it bio-degrades. Moreover some of the bio-plastic conceptions can even accentuate upon the quality of soil when used in a local scale.

The low down:

The main concern could be over the use of genetically modified organisms (GMO), as there are always possibilities that GMOs could introduce new allergens into the procedures. Adding to that, the whole familiar recycling system has to undergo serious changes. An apt example would be - plastics like PET do not mix with PLA (Polylactic acid plastics from cane sugar or glucose); yielding unusable recycled PET if consumers fail to distinguish the two in their sorting. And lastly, there are some real concerns that the creation of a global bio-economy could contribute to an accelerated rate of deforestation, if not regulated effectively.

The impact:

As already mentioned, the usage of bio-plastics on a massive scale can reduce our emissions by significant levels. Plastic has always proven to be a bane to a sustainable environment, but much because of its economic viability and malleability it has lingered and rather thrived. Now bio-plastic could be that all important alternative to conveniently replace plastic. They can substantially deplete the quantity of hazardous waste caused by oil-derived plastics, albeit in a controlled state. This would certainly add a new 'green' dimension to our modern packaging industry, which forms a crucial element of our overall economy.

Some Other Alternatives to Plastic

1. Glass

Plastic is derived from fossil fuels while glass is made out of sand. Hence, glass does not contain any harmful chemicals like plastic. If compared to plastic, glass is easy to recycle. In addition, you can reuse glass for several purposes, including storage containers, candleholders, flower vases, etc, in your home.

2. Liquid Wood

Image Source : Architerials

Liquid wood is a biopolymer that can act and behave just like plastic. However, it is derived from pulp-based lignin and thus, is both renewable and biodegradable. This would make a perfect alternative for those who like the feel of plastic, but still want to protect the environment from petroleum-based products.

3. Jute Fiber

Jute fiber bags are becoming a mainstay in many shopping outlets that have vowed to stop using plastic bags. Apart from being more durable than plastic bags, jute fiber bags are easy to wash and reuse multiple times. You can carry these jute fiber bags while shopping and avoid using the plastic bags offered by stores.

4. Milk Protein

Although milk protein is too hard and brittle for normal use, scientific advancements have led to the creation of milk protein that is more flexible and does not pose risks of cracking when bent. This milk-based plastic can emulate the qualities of petroleum-based plastic, but is biodegradable and thus, eco-friendly.

5. Corn based plastic

Research in the field of biodegradable plastic alternatives has led to the development of a corn based plastic called polyactides (PLA) which can decompose within just 47 days of landing up in a dump. Made of corn, PLA does not release any toxic fumes when burnt. PLA based plastics can be used for manufacturing cups, containers, utensils and other consumer products.

# data[].attributes.attachment_link.title
Bioplastics: Advantages, Disadvantages, Trends, and more - Ecofriend

# data[].attributes.attachment_link.description
The main reason why plastic is becoming so problematic is that it is immensely useful. We are using it in almost every sphere of life. In fact, no matter wherever you look, it is almost impossible to not find plastic there. Now more than ever we are facing the dilemma.

# data[].attributes.attachment_link.description
Jutin is the flagship product in our BTTR Board product line. It’s our plant-based alternative to traditional polyester resin, typically used in the construction, automotive, and aerospace industries. The structural integrity of the material is reinforced by jute - an abundant, low-maintenance, indigenous crop grown in Bangladesh. Jute replaces up to 50% of petroleum-based inputs in our composite, resulting in a significantly lower plastic volume per unit.

# data[].attributes.attachment_link.description
Sustainable Materials Designed With Tomorrow in Mind.