PFAS Linked to Thyroid Cancer Risk in Humans
One PFAS compound was associated with a 56% increase in thyroid cancer.
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Some per- and polyfluoroalkyl substances (PFAS) – also known as “forever chemicals” – may be linked to an increased risk of thyroid cancer, according to a study from Mount Sinai School of Medicine. The research is published in eBioMedicine.
PFAS is the name given to a group of thousands of complex chemicals suited for a variety of applications owing to their extreme durability. They have been widely used since the 1940s and are commonly found in firefighting foams, water-repellent clothing and non-stick cookware.
However, PFAS also come with considerable downsides. They can leach into and accumulate in the environment – polluting soil, water and air – and have been linked to numerous negative health outcomes such as fertility problems, low birth weight and cancer.
Although PFAS exposure has also been linked to some cancers as well as thyroid dysfunction, studies investigating potential associations between PFAS exposure and thyroid cancer have so far been lacking. Meanwhile, the number of thyroid cancer diagnoses is on the rise.
Mount Sinai researchers studied this area in more detail to probe whether there is indeed an association between blood PFAS levels and risk of thyroid cancer diagnosis.
“PFAS are chemicals that are known to disrupt the function of endocrine organs, such as the thyroid gland,” says Dr. Lauren Petrick, co-senior author of the study and associate professor in the Icahn School of Medicine at Mount Sinai, speaking to Technology Networks. “We therefore hypothesized that PFAS exposure may be one of the potential risk factors for thyroid cancer and thus one of the potential reasons for the increasing thyroid cancer incidence.”
“To our knowledge, this is the first human study to look at associations between PFAS exposure and risk of thyroid cancer diagnosis,” Petrick adds.
Thyroid cancer and PFAS
The researchers measured PFAS levels in blood samples using data from BioMe, a medical record-linked biobank at the Icahn School of Medicine. A total of 88 thyroid patients (whose blood was collected either before or at cancer diagnosis) and 88 control participants (who did not have any form of cancer and were matched by sex, ethnicity, age, etc.,) were assessed.
Levels of eight individual PFAS were compared between the thyroid cancer patients and control participants using various statistical models. This revealed that exposure to one PFAS in particular, perfluorooctanesulfonic acid (n-PFOS), was associated with a 56% increase in thyroid cancer.
The researchers next looked to determine if there was a lag time between PFAS exposure and thyroid cancer diagnosis. They narrowed their search to a subgroup of 31 thyroid cancer patients whose blood had been collected at least a year between their enrolment in BioMe and their diagnosis.
This second analysis also revealed an association between n-PFOS and thyroid cancer, as well as several other PFAS chemicals – such as branched perfluorooctanesulfonic acid, perfluorononanoic acid, perfluorooctylphosphonic acid and linear perfluorohexanesulfonic acid.
Exploring other associations with thyroid cancer
Petrick also goes on to address some of the limitations of the study, including the need for further studies with more participants: “This study was performed on a small sample size, and it is important to repeat this study including a larger sample to confirm these results,” she says.
There is also scope for further analyses from this study, Petrick explains: “While in this paper we looked at eight PFAS chemicals, we also measured hundreds of other chemicals and metabolites at the same time. We’re currently looking to see if any of those chemicals and metabolites are also associated with thyroid cancer.”
“[…] one of the other next steps is to investigate if PFAS exposure is associated with a more aggressive type of thyroid cancer or a higher likelihood to have thyroid cancer return or develop a second cancer,” she adds.
Reference: van Gerwen M, Colicino E, Guan H, et al. Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer risk. 2023. eBioMedicine. doi: 10.1016/j.ebiom.2023.104831
Dr. Lauren Petrick was speaking to Dr. Sarah Whelan, Science Writer for Technology Networks.