Non-stick could cause thyroid disease, say researchers

The safety of non-stick coatings has been called into question again as new research shows that they may be linked to thyroid disease.

The University of Exeter study looked into perfluorooctanoic acid, otherwise known as PFOA, a chemical used in the manufacture of some non-stick coatings that becomes unstable at very high temperatures. The researchers say that of the 4,000 people taking part in the study those found to have the most PFOA in their blood were twice as likely to suffer thyroid problems.

One of the researchers, David Melzer, a professor of epidemiology and public health, said the analysis showed that “in the ‘ordinary’ adult population there is a solid statistical link between higher concentrations of PFOA in blood and thyroid disease”.

However, other research has failed to find a connection between the chemical and the disease.

The senior author of the study and professor in ecotoxicology at Exeter, Tamara Galloway, stressed that more studies had to be done on PFOA.

“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,” she said. “We need to know what they are doing.”

The suggestion of a link with thyroid disease is the latest in a long line of allegations about the dangers of PFOA. In the US, the Science Advisory Board for the Environmental Protection Agency has determined that it is likely to cause cancer.

And in 2004 people living near the West Virginia plant of Teflon manufacturer DuPont brought a class action lawsuit against the company, claiming that local water contaminated with PFOA had caused birth defects.

DuPont agreed to an out-of-court settlement, which included paying $50m to the residents and spending $10m on water treatment facilities to filter out PFOA. However, it denied any liability and said that PFOA posed no danger.

In a separate case launched in the US in 2005 DuPont was accused by a group of people of withholding the results of research showing that PFOA released toxic particles during domestic cooking.

However, the four-year-old case was dropped last year on a technicality. Had it gone ahead and the court ruled against DuPont the company could have faced a bill of $5bn.

After the case was thrown out DuPont said that “cookware coated with DuPont Teflon non-stick coatings is safe for its intended use”.