Chemical compounds from some labels can penetrate the plastic wrap that covers food and contaminate food packaged underneath, a team of researchers from McGill University have found. An experiment conducted on fish revealed that in several cases the concentration of one of these substances – bisphenol S – significantly exceeded the European Union safety standard.

In light of their findings – which are published this Thursday in the scholarly journal Environmental Science and Technology – the researchers recommend that Health Canada initiate a “chemical risk assessment”, a process that could ultimately lead to the establishment of Canadian standards.

The scientists reported their findings to the federal government last fall.

“When we see these kinds of results, we need to trigger what is called a risk assessment: that is, we will calculate whether this dose is acceptable or not for the consumer, since some levels far exceed what has been set as a maximum concentration in other countries,” said one of the study’s authors, chemist Stéphane Bayen, who is a professor in the Department of Food Science and Agricultural Chemistry at the University. McGill University.

Health Canada did not respond to our questions, sent in writing on Monday.

In their study, the researchers looked at thermal labels. Fish, meats, cheeses, fruits and vegetables: they are used everywhere in the grocery store to indicate the price, the barcode and the list of ingredients. They are often affixed when the products are wrapped with plastic wrap. The information on thermal labels appears through a chemical reaction generated with the heat emitted by a device.

For decades, bisphenol A (BPA) has been used in thermal papers to enable this reaction.

The use of BPA, considered an endocrine disruptor, is increasingly regulated around the world. It has been banned in Canada in plastic baby bottles for nearly 15 years.

Today, Bisphenol S (BPS) is used as a replacement for BPA in thermal papers.

“There are indications that BPS may have negative health effects that are similar to BPA,” the researchers warn in their paper published Thursday.

The authors add that the European Chemicals Agency opened a consultation in 2022 to explore the possibility of adding BPS to its list of “substances of very high concern”.

Professor Bayen’s team had already measured BPS in a multitude of foodstuffs in a first study published in 2020. Some of the foods analyzed were taken from packaged product stalls and the other from the fresh food counter.

“There are traces of a lot of things in a lot of foods. But there, finding such a high frequency of bisphenol S in food, it was not normal for us […], that’s what pushed us to dig where it comes from. »

In their most recent study, the researchers amassed 140 samples of food packaging, mostly in Montreal.

Styrofoam trays, plastic wrap, thermal labels, trays and absorbent pads: everything has been analyzed.

The researchers also detected other compounds. Among these is “D-8”, which is described by the authors as having effects similar to those of BPA.

They also found “TGSA” and “PF-201”, classified as “high risk” and “moderate risk” respectively by the U.S. Environmental Protection Agency for repeated exposure, they note. in their article.

PF-201 was measured in 11 of 40 labels and TGSA in 7.

The researchers then conducted a “controlled” experiment by collecting 24 samples of plastic-wrapped fish in the United States and Canada.

They separated the sample to isolate the part that was under the thermal label and the part found only under the film.

The European Union’s “Specific Migration Limit” regulates the maximum amount of a substance that can migrate from food packaging into food. It is set at 50 ng/g for BPS.

A sample taken under the label, collected in the United States, contained a BPS concentration of 1140 ng/g. Another, from a grocery store in Canada, had a concentration of 437 ng/g. A total of eight out of 24 under-label samples exceeded this standard after five days.

The researchers also note that this is the first time that migration of D-8, D-90 and PF-201 into food has been reported in the scientific literature.

“We felt that we needed to do a more in-depth risk assessment [on bisphenol S], but also on other compounds. We also found some that had gone completely under the radar, Mr. Bayen explains. We just have to make sure that there are no risks for them. »

“For us, our main message is that you have to stop the cycle of replacing a chemical substance with something and then realize later that it is not acceptable,” he adds.

In its chemical structure, bisphenol S is very similar to bisphenol A, which has been singled out for more than a decade for its adverse effects on human health. “So what worries us a lot about BPA, there’s reason to be worried about BPS as well, because it’s an endocrine disruptor. It’s an estrogenic substance, meaning it’s capable of activating estrogen receptors, so it acts like synthetic estrogen,” says Maryse Bouchard, professor of environmental health at the National Research Institute. scientist (who was not involved in the McGill study). BPS is also anti-androgenic, she adds. “So it just blocks the effect of testosterone. Relatively recent studies in humans show that BPS is associated with the development of obesity and diabetes, Bouchard says. “BPA was already associated with an effect called obesogenic a few years ago, and now what we discover is that BPS has an even more marked obesogenic effect than BPA. He is worse. »