(CN) – Compostable food packaging seemingly combines convenience with sustainability, but a study published Wednesday found the containers are leaching potentially harmful substances into the ground.
In a study published in the American Cancer Society’s Environmental Science & Technology Letters, researchers said that the nonstick, biodegradable containers are leaching man-made, oil-and-water-repellent chemicals.
Biodegradable bowls, cups and cartons can be added to compost piles, because they are made with materials that degrade relatively quickly. When mixed with food and yard waste, compostable packages break down into nutrient-rich matter for soil, reducing the need for chemical fertilizers and cutting down the amount of waste sent to landfills.
But scientists say they do not know whether putting the compost on crops is healthy for humans.
Researchers from Purdue University and Seattle-based environmental consultancy Zero Waste Washington examined the levels of chemicals in 10 compost samples from five states. Nine samples came from commercial composting facilities – seven of which accepted compostable containers – and one sample came from a backyard compost bin which didn’t contain any biodegradable packages.
The study found all the samples contained traces of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). These substances are “long-chain” per- and polyfluoroalkyl substances (PFAS), which are known to cause negative health effects because they do not break down and can build up over time.
The substances, which have been in use since the 1940s, are widely found in U.S. manufacturing and consumer products due to their flame-retardant properties and ability to repel oil and water, according to the U.S Environmental Protection Agency.
The chemicals can travel long distances through the air, seep into groundwater and move through soil, according to the U.S. Agency for Toxic Substances and Disease Registry. They are found in compostable pizza boxes, other food containers, carpets, leather, apparel and textiles.
According to the EPA, these man-made chemicals have been found in the drinking water in several communities across the country. This contamination is due to local industrial or firefighting facilities that produce the materials.
Studies show the chemicals have caused reproductive, developmental, liver, kidney and immunological effects in laboratory animals, and have caused tumors in animals.
In the samples from the seven facilities that accepted compostable food packaging, researchers found higher levels of the chemicals than in the facilities that did not accept such packaging.
Previous methods of assessing “compostability” of the biodegradable packages focused solely on physical breakdown of materials in controlled composting facilities, scientists said in the study, adding new standards will require container makers to ensure that fluid-repellent chemicals break down to levels below the established thresholds set by regulators.
Researchers said the results of the study contributed to the passage of Washington state’s Healthy Food Packaging Act of 2018, which bans the use of the chemicals in paper food containers. The ban will go into effect in 2022.
“This type of law will help prevent the use of products from other countries where PFAS-related bans may not exist because it focuses on the product and not where production occurs,” researchers said in the study. “Other sources of PFAS that may contribute to their presence in commercial compost should be evaluated including Gore cover technology.”
In an email, lead author Linda S. Lee of Purdue University laid out what the packaging industry – and consumers – must do next.
“They will need to invest in finding alternative protective coatings, which at this moment is likely to be a challenge. Also and as consumers realize more about this chemical class, they will start to look to support products that do not contain them,” Lee said. “Many may also choose not to compost their compostable packaging; however, I am not sure how widespread that is with individuals who compost.”
She added: “Based on what I knew at the time about protective coatings on packaging, I was not surprised that PFAS were present.”