Plastic trash has become one of the most visible global environmental crises of our time. Single-use plastics make up nearly half of all plastics produced, with 15 million metric tons of plastic now entering the ocean annually — equal to two garbage trucks dumping their loads into the sea every minute.
Plastics are everywhere: Found pole to pole, in clouds, drinking water, the stomachs of whales and seabirds, with bigger pieces degrading into centuries-lasting, often toxic micro- and nanoplastic particles that make their way into food and the human body — including our brains, breast milk and testicles.
With the next, and hopefully final, U.N. global plastics treaty negotiations set for a year-end meeting in Busan, South Korea, developing nations suffering the brunt of the crisis are calling for limits on plastic production. But industry groups propose a different solution that would allow single-use plastics production to continue apace: compostable and biodegradable bioplastics.
But as Mongabay recently reported, emerging research shows that bio-based plastics — made from corn, sugar beet, sugarcane, cellulose and other organics — can be just as toxic as petroleum-based plastics.
Now, a new report from Beyond Plastics, an NGO, makes a strong case that “biodegradable” and “compostable” plastics not only fail to live up to their sustainable promise — they could be harming ecosystems, farms that source bioplastic-contaminated compost, and people.
A garbage truck prepares to dump its load within view of a beach at Azua, Dominican Republic. There are no legally binding federal standards for bioplastic composting in the United States, or in most other nations.Image by Sandra Weiss for Mongabay
‘Worthless’ bioplastic compost
Many consumers will be surprised to learn that a certified plastic cup or container labeled as compostable can’t be put in backyard compost. It can often only be broken down under controlled conditions at a commercial composting facility, to which most communities lack access.
What’s more, according to the report, most U.S. commercial and municipal composters don’t accept compostable packaging, with only 46 of 173 U.S. industrial composters reporting they do. One reason is that organic farms, the main customers of composting facilities, aren’t allowed under current U.S. Department of Agriculture rules to use compost derived from compostable bioplastic packaging due to chemical contamination and bioplastic debris concerns.
According to voluntary American Society for Testing and Materials (ASTM) standards, a material is considered fully decomposed if more than 90% of it can pass through a 2-millimeter sieve. But that creates a loophole that allows compost to be chock-full of microplastics and nanoplastics. Research shows that fertilizers made at biogas facilities, for example, can have high levels of microplastics, including so-called biodegradable microplastics. A German study found that fertilizer coming from compost facilities contained large quantities of biodegradable plastics.
In an email to Mongabay, a representative of the Biodegradable Products Institute (BPI) said that, “Microplastics in compost are coming from conventional plastic contamination, not compostable products,” and pointed to a Spanish study showing no bioplastic contamination in commercially made compost.
However, other research shows that in complex natural environments, such as oceans or soils, bioplastics often don’t degrade as quickly as their proponents claim. One study found that biodegradable plastic bags were still fully intact three years after being buried.
“You’ll often have these promises made by companies that this is going to break down in five years, instead of 50 years, or 100 years, or whatever the comparison is with the traditional plastic,” says Susanne Brander, an associate professor and ecotoxicologist at Oregon State University. “But if you’re thinking about it from the perspective of an animal that might only live for a couple of years … it’s still going to be exposed to all of the breakdown products.”
According to Ulli Volk, deputy head of waste management and material flow management at Vienna Waste Management in Austria, who was quoted in the Beyond Plastics, bioplastics don’t add any nutrient value to compost and even harm the final product. “What composters really want are the food scraps; the bioplastic is collateral damage,” he said.
A February 2024 report by the Composting Consortium found that removing contaminants can comprise up to a fifth of a composting facilities’ operating costs. Biogas facilities, for example, remove all plastic wrapping, including bioplastics, from food waste and landfill it, thus negating the supposed benefit of using compostable foodware in the first place.
Meanwhile, consumers, misled by bioplastic labeled as compostable, will likely continue tossing it into the home compost bin.
Biodegradable foodware is often advertised as being compostable, but it can’t be composted in home compost piles or at most commercial compost facilities, according to the new report by Beyond Plastics, an NGO. Image by Scott Bauer via Wikimedia Commons (Public domain)
Hazardous compost can put health at risk
Even if bioplastics break down completely, they can release all manner of toxic additives, including PFAS and endocrine disruptors like BPA, none of which are banned from food-contact materials by the U.S. Food and Drug Administration.
A 2023 study found that compost containing biodegradable food packaging contained PFAS levels up to 20 times higher than compost from manure, food waste and yard waste. Another study published the same year found that in lab experiments, the chemicals in compostable plastic bags were more toxic to living cells than virgin and recycled plastics.
What’s more, photodegradation can lead to new toxic chemicals being created, leading the researchers to conclude that compost containing compostable bioplastics could be a significant source of environmental pollutants, potentially putting wildlife and human health at risk.
“It’s also been shown that particles that are smaller can be more toxic,” Brander says, pointing out that while biodegradable plastics may become smaller faster, that isn’t necessarily a good thing. Nanoplastics are “small enough to cross the epithelial lining of the gut. They’re small enough to get into the bloodstream if they’re inhaled, and get in through [fish] gills, for example, or in a terrestrial animal, through the lungs.”
Not all bioplastics are toxic. However, because manufacturers keep their formulations secret, there’s no way for consumers to distinguish between harmless and harmful bioplastics.
The chasing arrows universal recycling symbol is ubiquitous in plastics industry product labeling. However, its appearance on a product is mostly an empty promise, since there are many types of plastic, of which only limited types can be recycled and only by some facilities. When used in connection with compostable claims like those implied in this image, the meaning of the symbol is rarely defined. Image by imordaf via Pixabay (Public domain).
An industry sets its own standards
Some U.S. states, including California, Washington and Colorado, require manufacturers to adhere to ASTM standards for products marketed as compostable. In other states, Beyond Plastics reports “rampant greenwashing … Manufacturers are free to label products as biodegradable or compostable without meeting any standards. Moreover, many develop lookalike products deliberately intending to confuse consumers.”
Because the U.S. lacks federal standards, certification of compostable plastics is left to trade associations or private organizations that represent bioplastics manufacturers, according to the report. In Europe, the certification program run by TÜV Austria and DIN CERTCO is owned by the European Bioplastics Association, while the Australasian Bioplastics Association certifies products sold in Australia and New Zealand.
The Biodegradable Products Institute (BPI) is the United States’ main certifier of compostable packaging; it has no independent scientists or government officials on its board, but does include employees of petrochemical companies such as BASF and Eastman Chemical. Corporations certifying their products through BPI pay an annual membership fee that gives them a voice on the organization’s standards and procedures committee.
In 2023, BPI petitioned the USDA’s National Organic Standards Board to allow bioplastics as compost feedstock. The National Organic Coalition strongly opposes that petition, saying it would “lower our standards on compost, which would result in a contaminated input, cause market disruption for those selling truly acceptable compost, and lower the consumer confidence in the organic label.”
Responding to the Beyond Plastics report, BPI told Mongabay that its board is open to compostable-product manufacturers, composters and government officials, and that it engages “with academic scientists and other partners to continually update our requirements, ensuring they remain robust and credible.” It points to “multiple firewalls to avoid conflicts of interest,” including certification being built on public ASTM specifications, with conformity assessment and certification decisions made by DIN CERTCO, “with no ability of members to influence that decision.” BPI pointed to its prohibition of PFAS use in 2017, and its requiring of on-product labeling.
“BPI also recognizes that false and misleading claims around biomaterials can create confusion, which is why the organization has prioritized consumer testing, improved labeling, and policies that limit misleading terminology,” it said in a public response to the report.
Many bioplastics claim to be biodegradable and compostable. But the devil is in the details, and depends on the type of plastic, along with the potentially toxic additives left behind during degradation into microplastics and nanoplastics. In the U.S., there are no federal standards for plastic compostability. Image by The Bag N Box Man LTD via Flickr (CC BY 2.0).
A burden on small businesses
Beyond Plastics notes that bioplastic foodware and packaging can cost anywhere from double to six times the price of conventional plastics, putting a financial burden on restaurants trying to be more sustainable. The report, which is aimed at both consumers and small businesses who buy compostable plastic packaging and products like straws and takeout containers, includes a checklist to help restaurants and bars choose more environmentally friendly options.
Recommendations include eliminating single-use plastic, swapping plastic for a reusable or refillable system, or replacing plastics with more sustainable paper or cardboard products. Food businesses that currently use disposable plastic products can seek out organizations that advise on waste reduction, and on local reuse networks that take back reusable foodware, clean it, and redistribute it to businesses.
When plastics are truly necessary, Beyond Plastics recommends looking for GreenScreen– or Cradle to Cradle-certified products free of hazardous chemicals, while ensuring “compostable” plastics are either certified backyard compostable, or accepted by a local commercial composting facility.
Beyond Plastics is calling on policymakers to mandate and fund reuse infrastructure through legislation, including extended producer responsibility (EPR) laws that would make manufacturers legally and financially responsible for mitigating the impact of their products and packaging, and for container deposit laws that incentivize the return of plastic bottles.
“Instead of producing new kinds of single-use plastics that we don’t have the ability to manage downstream, why don’t we just rely on reusing things and eliminating a lot of these single-use items we don’t necessarily need?” says Brander. “We’re trying to solve this problem with all these new technologies, but we’re creating new problems to deal with.”
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