A recent study funded by the U.S. National Institutes of Health (NIH) has provided strong evidence linking the ingestion of per- and polyfluoroalkyl substances (PFAS) to thyroid cancer.
According to the study, incidence of thyroid cancer has substantially increased worldwide over recent decades (and in the U.S., has increased on average by 3.6 percent per year), and one potential reason for this trend is exposure to endocrine disrupting chemicals, such as PFAS. Also known as “forever chemicals,” PFAS do not break down and therefore accumulate in the body and the environment over time. The chemicals are present in food packaging and other food contact materials, like nonstick pans.
PFAS Linked to Thyroid Cancer
To investigate the association between PFAS and thyroid cancer, a team of researchers identified 88 patients with thyroid cancer who had plasma collected prior to or at diagnosis. The cancer patients were pair-matched with 88 healthy individuals in a control group based on sex, age, race/ethnicity, body mass index, smoking status, and year of sample collection. Patient data were collected from BioMe, which is a medical record-linked biobank at the Icahn School of Medicine at Mount Sinai in New York.
Using untargeted analysis with liquid chromatography-high resolution mass spectrometry and suspect screening, 18 individual PFAS were measured in the plasma samples, but ten PFAS were excluded due to non-detected intensities for more than 40 percent of plasma samples. The remaining eight PFAS included in the analyses were: linear perfluorohexanesulfonic acid (n-PFHxS), perfluorooctanoic acid (PFOA), perfluoroheptanesulfonic acid (PFHpS), perfluorooctylphosphonic acid (PFOPA), branched and linear perfluorooctanesulfonic acid (Sb-PFOS and n-PFOS), perfluorononanoic acid (PFNA), and n-methylperfluorooctanesulfonamidoacetic acid (N-MeFOSAA).
The researchers found a 56 percent increase in the rate of thyroid cancer diagnosis per doubling of n-PFOS intensity, suggesting that there is strong biological plausibility linking PFAS exposure to thyroid cancer risk.
Although industry and regulators are beginning to phase out PFAS chemicals of highest concern, such as PFOS and PFOA, measurable levels remain in the U.S. and European populations due to their persistence in the environment and in human bodies, the researchers warn. The half-lives of PFOS and PFOA in water are 41 and 92 years, respectively, meaning that individuals will continue to be exposed to the potential of carcinogens through contaminated public drinking water systems.
The Pervasiveness of PFAS and Efforts to Mitigate PFAS Contamination
In October 2023, the UK Royal Society of Chemistry presented the findings of an analysis revealing that more than a third of water courses in England and Wales contain medium- to high-risk levels of PFAS, and is called upon the UK Government to overhaul its drinking water standards. Additionally, in July 2023, the U.S. Geological Survey (USGS) announced that nearly half of all U.S. drinking water is contaminated by PFAS, and stressed the need for point-of-use tap water monitoring with an emphasis on unmonitored private wells and underserved communities on small community water supplies.
Although some regulatory bodies and companies are looking to end the use of legacy PFAS, studies have shown that replacement PFAS heralded as “safe” for use in food packaging may still break down into toxic PFAS in the human body and the environment. Still, in a March 2023 draft final rule, the U.S. Environmental Protection Agency (EPA) revealed its intent to regulate as contaminants six PFAS considered to be harmful, under the Safe Drinking Water Act. Some U.S. states have already passed bans on intentionally added PFAS in food packaging, specifically: California, Colorado, Connecticut, Hawaii, Maryland, Maine, Minnesota, New York, Oregon, Rhode Island, Vermont, and Washington.
Some major retail foodservice brands, such as those owned by Restaurant Brands International, have announced their commitment to phasing out PFAS in their packaging, and 3M has decided to stop manufacturing all PFAS by the end of 2025.