Switching to biodegradable plastics could slash toxic pollution by more than a third and dramatically reduce global waste by mid-century but only if cities and companies invest in the right disposal systems, a Yale School of the Environment study found. Without proper composting facilities, the bio-based plastics could double greenhouse gas emissions.

Faculty

Yuan Yao

Associate Professor of Industrial Ecology and Sustainable Systems; Director of the Center for Industrial Ecology

The research published in Nature Reviews Clean Technologyis the first to project the environmental impact of biodegradable plastics through their entire lifecycle at a global scale, from the acquisition of raw materials through all end-of-life possibilities, including if they end up as microplastics in the environment.

The findings show that substituting as much conventional plastic as possible with biodegradable alternatives could reduce ecotoxicity up to 34% by 2050, with little change to energy demand. It would also reduce global waste accumulation up to 65% when combined with ideal waste management for conventional plastics.

Achieving these benefits, though, requires that the materials are properly managed at end of life with methods such as industrial composting and anaerobic digestion. If biodegradable alternatives end up in landfills, it could double greenhouse gas emissions. The researchers also found that production of bio-based alternatives would increase the industry’s water footprint more than twice the current amount, largely because of the water required to grow biomass.

“Biodegradable plastics can definitely help with plastic waste accumulation and ecotoxicity, but the benefits may not hold if their end-of-life isn’t managed properly,” said Yuan Yao, an associate professor of industrial ecology and sustainable systems and the study’s senior author. “We need to have more infrastructure for the proper treatment of biodegradable plastics, and we need to have good education for how to use them.”

The study builds on research Yao and postdoctoral associate Zhengyin Piao conducted in 2024 in which they developed a method to assess the environmental impacts of biodegradable microplastics in waterways. That earlier research uncovered a trade-off: faster degrading options led to lower ecotoxicity but more greenhouse gas emissions.

The method they developed in the earlier research also enabled them to forecast the impact of plastic production across multiple dimensions of sustainability, and they used that in the new study to account for what portion of conventional plastic technically could be replaced, different scenarios for waste management, increases in global plastic use, and variations in local conditions, such as temperature. 

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The researchers said the findings highlight the need to maximize the benefits of the growing biodegradable plastics market, including more research into water-efficient raw materials and investments into expanded waste management infrastructure — from anaerobic digesters for biodegradable plastics to facilities for recycling and treating conventional ones. They also pointed to the need for standardized labeling schemes to avoid consumer confusion and to ensure plastics are separated and disposed of properly.

“Biodegradable plastic is not just one thing,” Yao said. “It’s a very big group of different kinds of plastics, so one important question is how we label those different materials and educate consumers about the differences.”

The authors also stressed that biodegradable plastics are only part of the solution.

“Conventional plastics will still dominate the future plastic market, and if we do not address conventional plastics, we cannot effectively reduce waste accumulation,” said Piao, lead author of the study. “But if we consider a combined strategy — minimizing the landfilling of conventional plastics and increasing use of biodegradable plastics at the same time — we can flatten the trend of future waste accumulation.”