Are biodegradable plastics really worth the hype?

The global annual production of plastics rose to 400 million metric tons in 2022 and is projected to double by 2050. Many items produced are single-use, and less than 10% of plastic waste is recycled.

In August 2025 more than 2,600 participants from United Nations Member States gathered — for the fifth time — to negotiate a deal to end plastic pollution, but failed to bridge fundamental divides over binding versus voluntary measures. Nations with a vested interest in oil and plastics production that call themselves the "like-minded group" insist that the treaty cover only plastic recycling and consumption and oppose curbs on production.

Clearly, the problem of plastic pollution in land and marine environments isn't going away. This series looks at some approaches to dealing with it, starting with the development of alternative materials.

We constantly see images of unsightly plastic pollution — rivers clogged with floating rafts of debris so dense you can't see the water, beaches piled with plastic trash rendering them unfit for even walking on, plastic bags fluttering from roadside vegetation. Aesthetics alone make a compelling case that something must be done.

But unsightliness is the least of many problems with plastic pollution.

In a paper published July 2025 in the journal Nature, scientists presented an inventory of 16,325 known plastic chemicals and identified more than 4,200 as chemicals of concern — meaning they're toxic, do not naturally break down in the environment, or accumulate in organisms. Released throughout the plastic life cycle, these chemicals constantly expose people and environments, often with serious consequences.

These chemicals are intentionally or unintentionally added across the plastics life cycle, from extraction of raw materials to end of life, says Susanne Brander, associate professor in the Department of Fisheries, Wildlife, and Conservation Sciences at Oregon State University's Coastal Oregon Marine Experiment Station.

"There is no way to predict how many chemicals are in an individual plastic item," she says. "The biggest take-home is that it's not like there is one type of plastic that is safe. All have these mixes that are potentially problematic." Only 6% of all plastic chemicals are regulated internationally, and about 1,000 are subject to national regulations.

Once out in the world, plastic physically breaks down into ever smaller particles. Pieces less than 5 millimeters across, called microplastics, have long been recognized as the prevalent form of plastic pollution in marine and coastal environments. Toxic and endocrine-disrupting chemical substances adhere to the surface of microplastics, a process known as adsorption. Marine birds and plankton-eating organisms such as fish and corals ingest microplastics and introduce these chemicals into the food chain. Recent studies have found microplastics in human organs and tissues, with effects including cell aging, changing gene expression, increasing oxidative stress, and inflammation.

Now researchers report that nanoplastics are present in the ocean in amounts comparable to microplastics. Nanoplastic particles have diameters less than one micrometer (a human hair is about 100 micrometers thick). The uppermost layer of the North Atlantic contains an estimated 27 million metric tons (almost 30 million U.S. tons) of these particles.

At this smaller size, materials behave differently. Lacking buoyancy, particles may "rain" down into ocean depths. They can cross cell barriers in the human lung and intestine and may affect biological systems at the cellular or even molecular level.

Making a better plastic

An oft-floated solution to plastic pollution involves making the materials biodegradable — meaning they are naturally broken down by organisms like bacteria or fungi into water, carbon dioxide and biomass, such as soil. The rate at which this happens depends on the type and number of organisms and factors like temperature, light, and exposure to air. "Compostable" refers to materials that biodegrade relatively quickly under specific, human-driven conditions.

The current draft of a proposed United Nations global plastic treaty suggests making plastics biodegradable as much as possible. The U.S. National Academies of Sciences, Engineering, and Medicine recommends redesigning plastic products using principles of green chemistry and engineering.

But this must be done correctly, stress the authors of a June 2025 letter in the journal Science. Most current "biodegradable" plastics are composites of bio-resourced materials — natural materials like wood and other fibers — and petrochemical-based materials. The letter points to research showing that when these materials weather they release potentially harmful chemicals into the environment. Those include terephthalic acid and bisphenol A, which have been shown to cause genetic, reproductive, and immune disruption.

Developers of biodegradable plastics, the letter goes on, must identify how these toxic ingredients degrade and design the materials for controlled and complete degradation.

Other scientists, including Brander, have urged phasing toxic chemicals out of plastic production altogether.

Another issue is the difficulty of separating the individual components in fossil-fuel based composite materials. As a result, most items made from them are landfilled or incinerated at the end of their service life rather than recycled or composted. Scientists note that changing the design and choice of materials could help address that.

But there also can be issues with the source of the "bio" side of these materials.

One, polylactic acid (PLA), is made from corn or sugarcane. The Plastic Pollution Coalition reports that these feedstocks often require intensive agricultural practices, contributing to problems such as deforestation and water pollution. Bioplastics make up only 1% of global plastics but require about 800,000 hectares (nearly 2 million acres) of arable land. Further, these materials typically are produced and manufactured in industrial facilities that run on fossil fuel.

Cellulose diacetate (CDA) is a bioplastic made from wood pulp treated with acetic acid, already used in consumer goods like straws and food wrappers. Research presented at a 2009 workshop on microplastic marine debris hosted by the National Oceanic and Atmospheric Administration suggested that very little CDA-based material biodegraded in marine environments. However, subsequent studies have showed that microbes can break it down in soil, wastewater, and the ocean.

Brander points out that testing of biobased plastics shows they break down into micro- and nanoparticles just like other plastics and can contain the same chemical mixtures. She adds that the way scientists test the degradation of these materials can be problematic.

"When I read papers about how about how [a material] breaks down completely, those claims often bear out in the lab," she says. "But in the real world, there may not be the right temperature or conditions. We need to think about conditions beyond the lab."

Scientists at Woods Hole Oceanographic Institution in Massachusetts recently did just that, using a tank of continuously flowing seawater from Martha's Vineyard Sound — which replenished natural microbes and nutrients — and controlling variables like temperature and light to mimic the natural coastal marine environment.

They tested foamed and solid CDA in this setup for several months and found that the foam version degrades much faster, according to Collin Ward, a marine chemist at WHOI and senior author on the paper.

"Foaming the material makes more surfaces for microbes to attach to, which accelerates degradation," Ward says. Microbes turn the material into food, creating carbon dioxide and water as byproducts.

The work focused on conditions in the coastal ocean, as that is where much plastic ends up, but the material also biodegraded in other conditions.

"It's a promising technology," Ward says. "CDA won't replace every piece of Styrofoam used, but it is a priority to find alternatives for materials highly leaked into the environment." His paper reports that about 15% of all plastic collected in beach surveys globally in 2022 was plastic foam take-out containers.

CDA still has drawbacks, though. Like other forms of plastic, its production is often energy-intensive and generates chemical waste. Applying the principles of green chemistry and engineering to CDA manufacturing could partly address these issues.

The source of the cellulose also is a potential drawback to CDA, just as with PLA. One way to minimize that problem would be for manufacturers to sustainably source wood pulp through programs such as the Forest Stewardship Council Chain of Custody certification. Using materials such as industrial or food waste or feedstock produced on marginal agricultural land also would be more sustainable.

Cost may be CDA's main drawback.

"The CDA material costs more to make than plastic," Ward says. "Consumers have to decide whether they want to keep the status quo of normalized plastic pollution or are willing to invest in technologies to reduce the amount."

Of course, plastic pollution itself has a cost, and healthy ecosystems have economic value. According to Ward, economic analyses show significant savings from switching to material that doesn't persist as pollution. One study estimates that diverting plastic packaging material that currently ends up in the ocean would put around $80 to $120 billion back into the global economy.

Any alternative plastic has a significant drawback, though: perpetuating the concept of single-use items. Even if it degrades in weeks or months instead of decades, that is still a lot of trash piling up. Tellingly, the first recommendation of the National Academies report and a major goal of the proposed UN treaty is to reduce plastic production.

One way to do that is to focus on essential uses for plastic. Consider that the average plastic bag is used for 12 minutes.

"Do we really need to make something that is used for 12 minutes and then thrown away?" asked Brander. "Let's use plastic for things that keep people alive, versus for carrying groceries."

Individuals and businesses reducing their demand for single-use plastic could go a long way toward solving this problem.

And there is still hope for the treaty, Brander says, with new delegates and a new chair in place. An editorial in Science suggests an alternative negotiating process, perhaps led by a convener other than the UN. The International Union for Conservation of Nature (IUCN), for example, initiated and facilitated the process 50 years ago that led to the international treaty known as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

But whatever happens with the treaty, and wherever design and engineering take plastics in the future, solving plastic pollution will take effort, Brander stresses. "There is not a quick fix where we can maintain this lifestyle without an impact."

This story was originally published by The Revelator.