New study links C8 to thyroid disease

PARKERSBURG - A report released this week by the journal Environmental Health Perspectives said a study by the National Institute of Environmental Health Sciences found an association between C8 and thyroid disease in adults.

The study, according to the report, revealed people with higher concentrations of PFOA (C8) in their blood have higher rates of thyroid disease. The researchers analyzed samples from the U.S. Centers for Disease Control and Prevention's nationally representative National Health and Nutrition Examination Survey. The study was done at the University of Exeter and the Peninsula Medical School.

Those conducting the study said more research is needed.

"As indicated by the authors of this study, the observed association is a correlation, which may or may not be causal. In addition these results are not consistent with other studies. Epidemiological studies, of workers who have had much higher levels of PFOA exposure than the general public, have not shown any changes that would indicate impact to the thyroid," according to a statement released by DuPont officials through external affairs spokesperson Robin Ollis-Stemple at the DuPont Washington Works plant.

Comprehensive cross-sectional and follow up on analysis of associations with thyroid disease have not yet been reported by the C8 Science Panel, named as part of a settlement in the C8 class action lawsuit brought by Mid-Ohio Valley residents against DuPont Washington Works. That information is expected to be released in 2010-2011.

According to this report an analysis was done of the chemical perfluorooctanoic acid against disease status in health and nutrition exam surveys done from 1999-2000, 2003-2004 and 2005-2006 that included nearly 4,000 adults with measured levels of the chemical in their blood.

The report concluded "higher concentrations of serum PFOA and PFOS are associated with current thyroid disease in the U.S. general adult population." The report goes on to note "more work is needed to establish the mechanisms involved and to exclude confounding and pharmacokinetc explanations."

The study attempted to determine whether increased serum PFOA or PFOS concentrations were associated with thyroid disease in a general adult U.S. population sample. The study noted "the prevalence of thyroid disease is markedly higher in women than in men."

The study refers to the largest human study of PFOA, which was conducted in the Mid-Ohio Valley as part of the suit's settlement. The C8 Health Project measured PFOA concentrations in more than 69,000 residents.

The report, released this week, notes "further work is clearly needed to characterize the PFOA and PFOS associations with specific thyroid diagnoses and thyroid hormone levels in the general population."

According to reports in Science Daily on the study, by the University of Exeter and Penisula Medical School the scientists found the 25 percent of the population with the highest levels of C8 had twice the incidence of thyroid problems.

Researchers from the University of Exeter said they had demonstrated an association but had not proved causality. "Our results highlight the need for further research," they said.

Reaction from other experts was skeptical. Ieuan Hughes, professor of paediatrics at the University of Cambridge and chair of the Committee on the Toxicity of Chemicals in the Environment, said the evidence for the link was "tenuous."

C8 is used in the manufacture process of Teflon and can be found in other stain and water-resistant coatings for carpets and fabrics.

According to the report, researchers found individuals with the highest 25 percent of PFOA concentrations (above 5.7ng/ml) were more than twice as likely to report current thyroid disease than individuals with the lowest 50 percent of PFOA concentrations (below 4.0ng/ml). There were 163 women and 46 men who reported having current thyroid disease and who were taking thyroid medication at the time the blood samples were taken.