Recycling food waste nationwide would have huge climate benefits, but a new study in the journal Nature Food found it could also pollute soil with microplastics if changes aren’t made to food packaging.
In the United States, about a third of food produced is never eaten, according to the Environmental Protection Agency. Producing, packaging and disposing the wasted food in landfills is a major contributor to climate change, and the EPA has a goal to cut the country’s food waste in half by 2030.
Some states have already taken steps in this direction. Massachusetts requires any business producing more than a half-ton of food waste per week to keep it out of landfills or incinerators. Instead, businesses must “recycle” by diverting edible surplus food to charities or food recovery services, and sending food waste to compost facilities or anaerobic digesters that turn it into energy.
Massachusetts now diverts about 370,000 tons of food waste from landfills per year, and has a goal of 780,000 tons annually by 2030. Vermont goes even further, prohibiting all residents and businesses from throwing food scraps and yard waste into household trash or landfills.
Researchers at the University of Vermont wanted to know what would happen if similar food waste bans were adopted nationwide. They found that recycling food scraps instead of tossing them in a landfill them could drastically reduce greenhouse gas emissions from food waste, cutting the total climate impacts by up to 99%. Nationwide food recycling would also reduce nutrient pollution from landfills that can feed toxic algal blooms.
But, without changes to food packaging, a national food waste ban could end up dumping up to 20,000 tons of plastic into farmland each year via contaminated compost.
“There are huge climate benefits to diverting food waste away from landfills. And a lot of that benefit is coming from avoiding methane emissions when the food waste breaks down,” said Katherine Porterfield, the lead study author and a postdoctoral fellow at the University of Vermont.
But, she said, a lot of plastic food packaging gets mixed in with food waste, either by accident or through sloppy sorting. Even with people and machines picking the plastic out of the waste stream, she said, ”a small amount sneaks through. And if you’re talking about very, very large amounts of food waste, that can add up.”
Porterfield said that food waste is only one way that microplastics can enter the environment. “Plastics are everywhere,” she said, and can get into soil from the air and water, stormwater runoff, and through plastic mulching used on many farms.
It’s unclear whether plastics in agricultural soil can end up in food in a significant way. “It’s still something that researchers are trying to understand,” Porterfield said.
The new study highlights “a real problem,”said Laura Orlando, senior scientist at the nonprofit Just Zero, who was not involved with the research. “Plastic doesn’t belong in compost — full stop.”
But, she added, compost made from food waste is not inherently contaminated with plastic; many gardeners, farmers and others are able to use food scraps as an ingredient in high-quality plastic-free compost.
“An upstream solution is to take plastic out of packaging,” she said.
There has been growing concern about the contamination of compost with PFAS, microplastics and other pollutants. In 2022, an organic compost facility was linked to contaminated drinking water in Westminster, Massachusetts.
The study authors said their findings should not discourage municipalities from enacting food waste bans.
“The study shows clear benefits to food waste recycling. This is something we need to be doing,” said study senior author Eric Roy, who directs the University of Vermont’s Casella Center for Circular Economy and Sustainability.
Casella Waste Systems Inc., a major waste management company in the Northeastern U.S., is a financial supporter of the research. Roy said the company had no influence over the study design or results.
He said that better sorting of food waste, as well as better packaging, could cut down on a lot of plastic waste.
“ Packaging is designed to package food, not to be de-packaged,” he said. “Conventional plastics tend not to disappear, but to just break into tinier and tinier fragments over time. So there’s work to be done.”
This article was originally published on WBUR.org.
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