Alternative plastics labeled as “compostable” still contain hazardous chemicals

While compostable plastics may reduce physical pollution, a recent study published in Aquatic Toxicology found that they are not necessarily less toxic than conventional plastic products and may actually carry more chemical hazards.

In short:

• When compared to conventional plastic products with the same purpose, almost all compostable plastics tested had higher chemical hazard levels.
• The compostable plastics were more likely to contain higher levels of toxic phthalate chemicals.
• Compostable plastics’ ability to break down increases their potential for releasing harmful chemicals into the environment, adding to their hazards.

Key quote:

“The high levels of phthalates … in plastics marketed as "bio" or "eco" raise serious questions about the misuse of these green labels, a commercial practice known as green washing.”

Why this matters:

As more regulations attempt to tackle the issue of plastic pollution, many single-use plastic items are being replaced with compostable materials. Because these compostable materials contain many of the same — and in some cases, more — chemical additives as conventional plastics, marketing that labels them as “green” or “eco-friendly” is misleading. The authors of this study call for a “paradigm shift in chemical regulation,” which requires new plastic chemicals to be “rigorously tested for safety” before they are introduced to the market.

Related EHN coverage:

• Bioplastics are inadequately defined, poorly regulated, and potentially toxic: Report
• Bioplastics: sustainable solution or distraction from the plastic waste crisis?

More resources:

• Beyond Plastics: REPORT: Demystifying Compostable and Biodegradable Plastics
• Beyond Plastics: The False Promise Of Bioplastics and Compostable Plastics.
• Environmental Protection Agency: Frequently Asked Questions about Plastic Recycling and Composting.

Beiras, Ricardo et al. for Aquatic Toxicology vol. 284. July 2025