POMEROY — The chemical used by DuPont at its Parkersburg, W.Va., plant and detected several years ago in local water supplies has been linked to thyroid disease in adults.

The new English study, completed at the University of Exeter, will be published in Environmental Health Perspectives, a peer reviewed publication.

Scientists testing the blood of 4,000 adults for the presence of the chemical between 1996 and 2006 found the 25 percent of samples with the highest C8 levels had twice the incidence of thyroid problems. The chemical has been shown to have adverse effects in animals, in which C8 has been proven to affect thyroid function.

Thyroid function is important for maintaining heart rate, regulating body temperature, and supporting other important systems in the body.

The results of the test, researchers said “highlight a need for further research.”

Perfluorooctanoic acid, also known as C8, has been used to make Teflon, stain and water repellents and other products and is made at the DuPont Washington Works plant near Parkersburg. It has been the subject of in-depth health studies designed to determine if it is hazardous to humans.

C8 was detected in local water supplies, including Tuppers Plains-Chester, Pomeroy and Mason County, W.Va. Residents in those and other water systems in the Ohio Valley participated in the C8 Health Project, and those results are being evaluated.

Those water systems have since been fitted with special treatment systems to address C8 contamination, as part of a class-action lawsuit filed by water customers in the affected systems.