Beware the wrapper

A recent study found 46% of food contact papers were contaminated with chemicals known to be detrimental to human health. Now, researchers have found a way of tracking these chemicals after they have migrated from the pack to the food and been ingested.

Perfluorinated and polyfluorinated alkyl substances (PFASs), present in many fast-food wrapping papers, can now be tracked when they enter the body. In a recent study of more than 400 packaging materials, 46% of food contact papers were contaminated with PFASs. Previous studies have shown that PFASs can migrate from the packaging, contaminate the food and then accumulate in the body.

Known to be harmful to the human body, PFASs are often used in stain-resistant products, firefighting materials and non-stick cookware, and are not meant for ingestion. Diseases including kidney and testicular cancers, thyroid disease, low birth weight, immunotoxicity in children and other health issues have been linked to PFASs in previous studies.

Research teams from the University of Alabama at Birmingham’s School of Medicine and the University of Notre Dame have developed a method whereby radiolabels are attached to three forms of the PFASs, enabling the scientists to follow the fate of these chemicals after ingestion.

The novelty of the newly designed method is that one of the fluorine atoms on the PFAS molecule was replaced with a radioactive form of fluorine (fluorine-18) — the same radioisotope that is used for medical positron emission tomography scans in hospitals around the world.

“For the first time, we have a PFAS tracer or chemical that we have tagged to see where it goes in mice,” said Suzanne Lapi, PhD, senior author of the study published in the Journal of Environment Science and Technology. “Each of the tracers exhibited some degree of uptake in all of the organs and tissues of interest that were tested, including the brain. The highest uptake was observed in the liver and stomach, and similar amounts were observed in the femur and lungs.”

Now that it appears likely that any PFASs that can be synthesised and isolated could be radiolabelled and used to directly measure uptake and biodistribution kinetics in biological systems, it opens the possibility of directly measuring uptake in human volunteers.

“This is possible since trace amounts of the compounds are easily measurable and the radioactivity short-lived,” said Graham Peaslee, PhD, the study co-author and professor of experimental nuclear physics in the College of Science at the University of Notre Dame. “It’s an important discovery because PFASs are a really persistent chemical that, once in the bloodstream, stays there and accumulates, which is not good.”

Now that researchers have identified which PFASs initially accumulate — and in which specific organs — and with some surprising differences, the authors say there are health implications far beyond this initial study.

“There was concern that these chemicals might directly enter the food that was wrapped with treated packaging,” said Peaslee, who used particle-induced gamma-ray emission to make the findings. “A larger concern is that, because these chemicals persist for a long time in the environment, when the treated consumer products enter the landfill, these chemicals will re-emerge into our drinking water. These overall results already call into question the safety of these alternative shorter-chain PFAS compounds.”

Lapi said the novel new tool developed by the research teams can be used for studying PFAS behaviour in environmental remediation studies to measure the fate of radiolabelled compounds in environmental treatment systems.

“This is a tremendous first step,” Lapi said, “and it underscores the need for further studies to aggressively investigate different PFAS compounds in different biological and environmental systems to assess the full impact of this novel radiosynthetic method.”

In addition to kidney and testicular cancer, scientists have previously found high cholesterol, thyroid disease, pregnancy-induced hypertension and ulcerative colitis to be correlated to the amount of perfluorooctanoic acid, or PFOA, found in the blood of people who were exposed to the tainted water.

As a result, the Environmental Protection Agency and US manufacturers reached a compromise to voluntarily remove two specific long-chain PFAS from the US market by 2015 — including PFOA. However, industry has switched from these long-chain forms of PFAS to shorter-chained versions of the same chemicals, Peaslee says. There is no toxicology data available for most of the alternative short-chain PFAS compounds used commercially.