Fluorochemicals cause thyroid disease – perhaps

Many scientists are on the look-out for links between persistent man-made chemicals and ill health in people.

The latest identification of a possible association is published today in the journal Environmental Health Perspectives.

Toxicologists at Exeter University and the Peninsular Medical School found that people with higher blood concentrations of perfluorooctanoic acid (PFOA) had higher rates of thyroid disease. PFOA is a persistent organic chemical used in industrial and consumer goods including nonstick cookware and stain- and water-resistant coatings for carpets and fabrics. The analysis used almost 4,000 samples from the US National Health and Nutrition Examination Survey.

“There have long been suspicions that PFOA concentrations might be linked to changes in thyroid hormone levels,” said study co-author David Melzer of the Peninsula Medical School. “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.”

The findings may be important because persistent perfluoroalkyl acids (PFAAs) such as PFOA are found in water, air and soil worldwide. But the mechanism by which they might cause thyroid problems is not known.

Independent experts urged people to treat the report with caution. Although the link found by the Exeter researchers seemed significant – people with the highest 25% of PFOA concentrations were more than twice as likely to report current thyroid disease than those with the lowest 50% of PFOA – many “confounding factors” might have caused the association.

Much more research will be needed to show whether or not there is a causal link.

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Clive Cookson, the FT's science editor, picks out the research that everyone should know about, in fields from astronomy to zoology. He also discusses key policy issues, from R&D funding to science education. He'll cover the weird and wonderful, as well as the serious side of science.