The findings are important because research has shown that PFAAs are found in water, air and soil throughout the world, even in remote polar regions. PFOA and PFOS have also been detected in the blood of people from across the globe, as well as in wildlife including birds, fish, and polar bears.

The main source of human exposure to PFOA and PFOS remains uncertain but is believed to be through diet. However, people may also be exposed through the PFAAs used in consumer goods such as textiles, footwear, furniture, and carpets, which can contaminate indoor air and dust.

Although more research is needed to understand the mechanism by which PFOA and PFOS may affect human thyroid functioning, it is plausible that the compounds could disrupt binding of thyroid hormones in the blood or alter their metabolism in the liver. However, this new evidence does not rule out the possibility that having thyroid disease changes the way the body handles PFOA and/or PFOS. The presence of the compounds might also prove to be simply a marker for some other factor associated with thyroid disease.

Thyroid diseases, particularly hypothyroidism, are much more common in women than men. However, in terms of the link between PFOA and thyroid disease, the researchers found no evidence of a statistically different effect between the sexes. The researchers also found a link between thyroid disease and higher concentrations of PFOS in men, but not in women.

Although previous studies of people living in communities near where PFOA and PFOS are manufactured did not find an association between exposure to these chemicals and thyroid hormone functioning, the largest study of such exposed communities is currently underway. (The 'C8' study of communities near DuPont's Washington Works plant, including Marietta, OH, and Parkersburg, WV, both in the US).

Source: The Peninsula College of Medicine and Dentistry