Several "forever chemicals" found nearly everywhere in our day-to-day lives have been linked to thyroid cancer, new research has found.
Certain per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals" due to their resistance to breaking down in the environment, have been associated with a 56 percent increased risk of thyroid cancer diagnosis. This is according to new research published in the journal eBioMedicine.
These PFAS chemicals have a strong carbon-fluorine bond, which prevents them from easily being broken down in the environment, allowing them to persist for many years. As these "forever chemicals" have been used in a wide range of products, including nonstick cookware, food packaging, water-repellent clothing, and stain-resistant fabrics, PFAS chemicals can be found in drinking water, household dust and even inside human blood.
Now, researchers at Mount Sinai Health System in New York City have quantified a link between the PFAS chemical perfluorooctanesulfonic acid (n-PFOS) and thyroid cancer risk.
Maaike van Gerwen, co-author of the paper and director of research for the Department of Otolaryngology at the Icahn School of Medicine at Mount Sinai, told Newsweek: "To our knowledge, this is the first human study to look at associations between PFAS exposure and risk of thyroid cancer diagnosis.
"What is unique to this study is that we were able to measure PFAS in blood samples collected around the same time that study participants were diagnosed with thyroid cancer and blood samples collected from roughly eight years to a year before they were diagnosed with thyroid cancer. This means that we can look at PFAS as a potential risk factor for thyroid cancer."
The researchers investigated the links between the amount of PFAS inside people's blood plasma and diagnosis of thyroid cancer using a medical record-linked biobank at Icahn Mount Sinai called BioMe. In it, 88 thyroid cancer patients and 88 non-cancer control patients of a similar sex, race, age, smoking status and BMI [body mass index] were studied, with researchers looking into how the levels of eight PFAS chemicals differed between the two groups.
They found that n-PFOS led to a 56 percent increased risk for thyroid cancer, and that there was a positive association between thyroid cancer risk and exposure to other PFAS including branched perfluorooctanesulfonic acid, perfluorononanoic acid, perfluorooctylphosphonic acid, and linear perfluorohexanesulfonic acid.
"Our results show that your risk of thyroid cancer increases by 56 percent when the level of linear PFOS, measured as intensity because of the untargeted assay that we used, doubles. So with increasing exposure levels your risk of a thyroid cancer diagnosis increases. This result was a significant result which means that it cannot be explained just by chance. This is the first study to find such a significant association between exposure to linear PFOS and thyroid cancer diagnosis," van Gerwen said.
"In the subset of study participants with PFAS measurements in blood collected years before diagnosis, we found several other PFAS associated with thyroid cancer. The risk levels were similar for these other PFAS chemicals, but it's important to note that this subset analysis was performed on a smaller number of participants, so we need to replicate these studies in larger populations."
While a 56 percent increase in risk sounds scary, it is important to know that this means a 56 percent increase of the original risk: for example, if the original risk was 1 percent, a 56 percent increase would result in a 1.56 percent risk, rather than a 57 percent risk.
Other PFAS chemicals are found in abundance in our daily lives, being discovered in menstrual products and clothing.
"PFAS are chemicals that have been produced since the 1940s and are used in a variety of industry and consumer products, including non-stick cookware, stain-resistant fabric and fire-fighting foam," van Gerwen said.
"The first PFAS chemicals that were produced were PFOA and PFOS. In the early 2000s, major American chemical companies voluntarily agreed to eliminate the production of PFOA and PFOA-related chemicals. This does not mean that the production of PFAS declined. On the contrary, multiple new PFAS chemicals were developed and are still being manufactured."
High levels of certain other PFAS have been previously found to be associated with increased blood cholesterol and blood pressure, reduced immunity and an increased risk of certain cancers, such as kidney or testicular, according to the U.S. Agency for Toxic Substances and Disease Registry.
"Because of the ubiquitous presence of PFAS in our environment, including water, soil and food, almost the entire population is exposed on a daily basis and it is thus difficult to completely avoid exposure," van Gerwen said.
"Our results are important to raise general awareness of the potential impact of PFAS on our health, including of health professionals and policy makers. Increased awareness may be warranted for people at risk of higher exposure to PFAS. The National Academies of Sciences, Engineering, and Medicine (NASEM) recommends PFAS testing followed by thyroid function testing in people with high PFAS exposure."
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