Whole Foods Market, hailed for its high standards for healthy food, ranked worst in a study of five major U.S. grocery chains for chemicals it uses in packaging at its popular hot-food bar. In response, the company said it has removed all the coated paper products in question and has started a search for new biodegradable packaging.

The study — released by watchdog groups Safer Chemicals, Healthy Families and Toxic-Free Future — found that Amazon.com Inc.’s grocer was the biggest offender when it came to food contact papers that appear to have been treated with a class of chemicals, some of which have been linked to cancer. They found high levels of fluorine in five of the 17 items tested at Whole Foods — four of which were containers for its salad and hot-food bar.

“Whole Foods Market introduced compostable containers to reduce our environmental footprint, but given new concerns about the possible presence of PFAS, we have removed all prepared foods and bakery packaging highlighted in the report,” the company said in an emailed statement. “We’re actively working with our suppliers to find and scale new compostable packaging options.”

Greater Scrutiny

The development highlights how chemicals known as PFAS (“pee-fas,” or per- and polyfluoroalkyl substances) are drawing greater attention from consumers. The substances are also the target of renewed scrutiny from the Environmental Protection Agency.

The policy change shows how companies like Whole Foods, which has built its brand on selling natural and healthy products and maintains a list of unacceptable items, can still struggle to live up to their lofty ideals across supply chains.

The presence of fluorine is a sign that the items were likely treated with a type of PFAS, according to the study. The concerns around the chemicals are multiple: They may migrate to food held in the containers and can linger for a lengthy period in the human body. Some types have been shown to hamper the immune system or promote cancer, and have been phased out. While newer varieties have yet to be tested, those that have been examined show problems, scientists say. Because they never degrade, packaging sent to landfills and compost can end up contaminating soil and water.

3M Co., a manufacturer of the chemicals, declined to comment. The company has said in the past that the chemicals are safe at the levels usually found.

Albertsons, Kroger

Other grocers, including Albertsons, Kroger and Ahold Delhaize NV, the owner of Food Lion and Stop & Shop, had fewer items that tested positive for the substance. These were usually deli or bakery papers. Trader Joe’s was the only company that had zero items.

“Trader Joe’s is asking its vendors to avoid the use of Per- and polyfluoroalkyl substances (PFAS) in packaging for our products. In addition, Trader Joe’s does not have food bars or delis, so takeout food containers are typically not found in our stores,” a spokeswoman for the grocer said in an email.

PFAS are widely used in waterproof or stain-proof fabrics, electronics, Teflon manufacturing, and 3M’s Scotchgard. The substances help prevent grease from soaking through paper in food contact materials.

Many kinds of PFAS are widely found in U.S. drinking water, and lawsuits from states, water districts and people who claim personal injury or property damage allege pollution through industrial sites or their use in fire-fighting foams.

“This is a step in the right direction,” said Mike Schade, who works with Safer Chemicals, referring to the Whole Foods announcement. He noted, however, that the chain hasn’t yet shared what alternative material it will be switching to. As director of the watchdog’s “Mind the Store” campaign that pushes health issues with retailers, he had raised the issue in a March 23 letter to Whole Foods, and recommended in September that Whole Foods take action on the issue.

Whole Foods containers were known as “Bio-Plus Terra II,” according to the study, which reported that Fold-Pak, the company making them, was using a product from Cascades Sonoco Inc. Cascades Sonoco has since moved to eliminate PFAS from the product, the study found. Fold-Pak and Cascades Sonoco didn’t immediately return messages seeking comment

The study is intended to push grocery stores to move to safer alternatives. A similar study in 2017 found that fast-food chains also used the chemicals.