New study indicates chemicals from grocery stickers may be leaching into foods. Here's what you need to know

The next time you're in the grocery store, you may want to take a look at how the fresh food is packaged. 

According to new research, toxic chemicals similar to bisphenol A (BPA) are leaching from certain labels through packaging, and into the meat, seafood, produce and other foods purchased in some Canadian and U.S. grocery stores. 

"We identified the thermal labels are a source [of BPA-like compounds] in our diet directly ... so far in the world, no one had identified that the packaging could be a source of bisphenol S to the diet," said Stéphane Bayen, a professor at McGill University in Montreal and senior author of the newly published study.

Bisphenol S (BPS) and BPA have been studied for their possible effects on health. Research has shown their ability to disrupt hormones and have negative effects on growth, brain function, the reproductive system and the immune system. Bisphenols have many applications and are frequently used in the manufacturing of various plastics and thermal paper.

Over the past decade, Canada has tightened its BPA regulations in an effort to phase out its use, including making it illegal to manufacture, import, advertise or sell baby bottles that contain BPA. 

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Meanwhile, BPS and other compounds highly similar to BPA remain unregulated and have been adopted as substitutes by the industry for various products, including thermal food labels — where you can find the price, best-before data, ingredients and other information on foods packaged in store.

As we've done more research into bisphenols ... the safety levels have consistently been lowered as we discover more and more about how these compounds work.- Glen Pyle, molecular cardiologist at the University of Guelph

Scientists have long warned that regulating BPA alone may not be making products any safer. Research at the University of Guelph in Ontario suggests BPS has similar effects to BPA on the heart, and literature reviews that synthesize available research have concluded BPS is equally or "more toxic."

Though BPA free, the thermal labels examined in the study by Bayen and his colleagues found they contained and transferred high amounts of related compounds — including bisphenol S (BPS) — that are known to have similar effects on humans as BPA. 

"Only a few [researchers] detected bisphenol S in food before [but] the source was completely unknown," Bayen said.

BPS level over 22 times higher than EU limit

The McGill study measured the concentrations of BPS and other BPA substitutes in labels, packaging and products purchased in stores. The research was published in March in the journal Environmental Science & Technology, with funding from  the Canadian Institutes of Health Research and the Canada Foundation for Innovation.

Grocery stores often use thermal food labels, which contain BPS to allow the paper to change colour when exposed to heat. 

The McGill researchers collected a total of 140 samples of food packaging materials from grocery stores in Canada (Montreal and Victoria) and the U.S. The materials in question, such as thermal labels, are used in almost all grocery stores. 

They tested the materials and the food inside for several BPA-like compounds, then measured their migration from the labels into fish from each store experimentally. 

The results clearly showed that BPS and other BPA-like compounds were leaching into the food from the thermal labels, while other packaging did not appear to be a significant source.

"The levels in which they found it ... exceeded the levels recommended by the European Union," said Glen Pyle, a molecular cardiologist at the University of Guelph who was not associated with the study. Pyle was part of the team that researched the effects of BPS on the heart. 

CBC reached out to Health Canada to comment on the latest research. In a statement, the federal department said the amounts of BPS in food are "currently monitored" and "are not considered to pose a health concern based on estimates of dietary exposure."

However, the data used to reach this conclusion does not seem to include fresh food. The statement linked to a series of reports by the Canadian Food Inspection Agency (CFIA), which tested canned food for various bisphenols, including BPS, and generally found little to none — nothing like the levels detected by Bayen and colleagues. 

Health Canada did not comment on the levels of BPS measured in this study. 

Unlike Canada, the European Union specifically regulates the amount of BPS that can migrate from packaging into food. Samples collected for the McGill study far exceeded those limits, with BPS transfer measured at up to 23 times higher than the 50 nanogram per gram wet weight limit.

Canada does prohibit the sale of food in packaging that may transfer harmful compounds to the contents. It is unclear what levels of BPS transfer would be in violation of that regulation. 

Pyle said those EU limits are evidence based and adjusted as new research emerges. 

"One of the interesting things that has occurred as we've done more research into bisphenols is the safety levels have consistently been lowered as we discover more and more about how these compounds work and the health risks they pose to humans."

How to minimize exposure to BPS

There are ways to reduce your exposure to BPS, said the experts who were interviewed. But they noted that thermal labels are widely used and a lack of regulation in Canada makes it difficult to know what contains the compound. 

Their recommendations include: 

• Bagging produce yourself rather than purchasing pre-packaged produce with thermal labels. 
• Picking up your meat from the butcher counter.
• Bringing your own container or aluminum foil and asking for it to be used to package fresh meat or fish. 
• Asking to have the label placed under the Styrofoam tray instead of on top (as researchers found that the parts of fish directly under a label had higher concentrations of BPS and other chemicals).

"Unfortunately, since the pandemic, we find every fresh food now is [packaged] in these trays with the thin film on top of it — meat, fish, seafood products — but now you can also find this for dairy products, for bread, sometimes for vegetables," said Bayen.

This shift is an issue, Bayen said, since compounds like BPS seem to be able to migrate from thermal labels into all of these products. 

Different stores varied in the levels of BPS and similar compounds in their labels. These other compounds the researchers detected included several members of the bisphenol family that are not well known.

"We should also have a look at these chemicals, but there's no information at all on on what would be a safe level ... so a lot more work has to be done," Bayen said. 

He feels the study also highlights some of the shortfalls of our current safety monitoring systems. 

"The way surveillance works is that we always look [for] what we know ... there is a need to to have all in our surveillance, to have tools that look for things that we didn't expect or we didn't know would be present."