A study published within the journal eBioMedicine finds that exposure to per- and polyfluoroalkyl substances can increase the danger of thyroid cancer in human populations.
Study: Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer risk. Image Credit: Created with the help of DALL·E 3
The Rising Threat of Thyroid Cancer
The worldwide incidence and mortality rates of thyroid cancers have increased significantly in recent many years. There was a mean of three.6% increase in thyroid cancer incidence per 12 months in america between 1974 and 2013. The same induction has been observed in China, Italy, and Turkey. Amongst 10 – 19-year-olds in america, a few 4.4% increase within the incidence rates of differentiated thyroid cancers (follicular and papillary thyroid cancers) per 12 months has been reported between 1998 and 2013.
Endocrine-Disrupting Chemicals: A Growing Concern
Excessive exposure to endocrine-disrupting chemicals is believed to be a possible risk factor related to increased incidence of thyroid cancers. Per- and polyfluoroalkyl substances (PFAS) are a gaggle of endocrine-disrupting chemicals utilized in industries and consumer products because the Nineteen Forties.
Ubiquitous Presence of PFAS
These chemicals have highly stable chemical structures and, thus, are ubiquitously present in soil, water, and air. As well as, PFAS could be present in many consumer products (non-stick cookware, stain-resistant fabric, and firefighting foam), food products, and drinking water. Evidence indicates that perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the 2 most generally used PFAS, and exposure to those chemicals is related to potential health hazards.
On this study, scientists have investigated whether exposure to PFAS can increase the danger of thyroid cancers.
Study design
A complete of 88 adult thyroid cancer patients with plasma samples collected at or before the cancer diagnosis were enrolled within the study. Amongst these patients, 74 had papillary thyroid cancer. The control study population included 88 healthy individuals who were pair-matched on age, sex, ethnicity, body mass index, smoking status, and 12 months of sample collection.
Plasma samples collected from the patients were analyzed by liquid chromatography-high resolution mass spectrometry to detect eight sorts of PFAS.
Key Findings and Their Implications
The correlation evaluation between PFAS exposure and thyroid cancer risk revealed a 56% induction in the speed of thyroid cancer diagnosis per doubling of linear PFOS intensity in the complete study population. Nevertheless, no significant association was observed between the opposite seven PFAS and thyroid cancer diagnosis rate.
Considering the patients with papillary thyroid cancer, the same positive association was observed between linear-PFOS intensity and thyroid cancer diagnosis rate.
Digging Deeper: Subgroup Analyses
A subgroup evaluation investigating the impact of exposure timing on thyroid cancer diagnosis was conducted on patients who were diagnosed at the least one 12 months after the sample collection. The findings of subgroup evaluation revealed that exposure to linear PFOS, branched PFOS, perfluorononanoic acid, perfluoro-octyl-phosphonic acid, and linear perfluoro-hexane-sulfonic acid can significantly increase the speed of thyroid cancer incidence.
The subgroup evaluation involving thyroid cancer cases diagnosed inside one 12 months after sample collection showed the same association just for linear PFOS but not for other PFAS tested.
Why PFAS Are Carcinogenic
The study finds that exposure to endocrine-disrupting chemicals like PFAS can increase the danger of thyroid cancers. Amongst various PFAS, essentially the most potent contributors are linear PFOS, branched PFOS, perfluorononanoic acid, perfluoro-octyl-phosphonic acid, and linear perfluoro-hexane-sulfonic acid.
PFAS are considered carcinogenic due to their ability to induce epigenetic alteration, immunosuppression, oxidative stress, inflammation, and disruption of hormonal and metabolic pathways.
Persistent Risk in Drinking Water
A significant source of PFOS and PFOA is water; the half-lives of those chemicals in water are 41 and 92 years, respectively. This highlights the danger of persistent exposure to potential carcinogens through contaminated drinking water, which in turn can significantly increase the danger of thyroid cancers worldwide.
Long-lasting Impact on Human Health
Moreover, the elimination half-lives of PFOS and PFOA in humans is 3 – 7 years. This means that these chemicals have a long-lasting ability to disrupt signaling pathways and induce potential health hazards.
Future Directions and Gaps in Research
The study has focused mainly on PFOS, PFOA, and other long-chain PFAS, that are a small proportion of the full variety of PFAS. Thus, scientists highlight the necessity for large-scale prospective studies to analyze the impact of exposure to additional PFAS on thyroid cancer risk.