The independent panel charged with studying the possible health effects of a chemical in West Virginia and Ohio wants to do its own study on the workers at a plant where the substance is used to manufacture Teflon.

Wilmington, Del.-based DuPont Co., which operates the Washington Works plant near Parkersburg, has done its own studies on death rates among workers, which the company says prove ammonium perfluorooctaonate, also known as C8 or PFOA, has no definitive link to human disease.