Non-stick chemical linked to thyroid disease

A chemical found in the coating of non-stick pans has been linked to thyroid disease, new research has found.

The chemical perfluorooctanoic acid (PFOA) is widely used to make water and stain resistant coatings for fabrics, carpets and other textiles as well as the lining of non-stick cookware.

However a new study of over 3900 adults in the United States has revealed that people with higher concentrations of PFOA in their blood have higher rates of thyroid disease.

Scientists from the University of Exeter and the Peninsula Medical School measured the concentration of PFOA and other perfluooalkyl acid (PFAA) compounds in blood samples taken from over 3900 adults between 1999 and 2006.

They found that people with the highest 25% PFOA concentrations in their blood (greater than 5.7ng/ml) were twice as likely to have thyroid disease than those with the lowest 50% PFOA concentrations (less than 4ng/ml).

Tamara Galloway, professor of Ecotoxicology at the University of Exeter and the study's senior author, said: "Our results highlight a real need for further research into the human health effects of low-level exposures to environmental chemicals like PFOA that are ubiquitous in the environment and in people's homes.

"We need to know what they are doing."

Study co-author, David Melzer, professor of Epidemiology and Public Health at the Peninsula Medical School also added: "There have long been suspicions that PFOA concentrations might be linked to changes in thyroid hormone levels.

"Our analysis shows that in the 'ordinary' adult population there is a solid statistical link between higher concentrations of PFOA in blood and thyroid disease."

Although thyroid disease is more common in women than men, the researchers found no evidence of a statistically different effect between the sexes.

Being highly resistant to heat, PFAAs are found in water, air and soil throughout the world, even in remote polar regions. PFOA and PFOS have also been detected worldwide in the blood of people as well as in wildlife including birds, fish, and polar bears.

PFOA can also be formed by the break-down of certain other highly fluorinated chemicals used in oil and grease-resistant coatings on fast-food containers and wrappers and in stain-resistant carpets, fabrics, and paints.

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

The study is published in the journal Environmental Health Perspectives.

This article was published on Thu 21 January 2010