A four-year-old lawsuit against DuPont Co., claiming the company's non-stick Teflon cookware is unsafe, has been dropped. U.S. District Court Judge Ronald Longstaff, presiding on the U.S. District Court in Des Moines, Iowa, signed a dismissal order on May 1, DuPont said. The class action case comprises 22 cases in 15 states.

According to an attorney representing some of the plaintiffs, the court determined the cases "did not meet the criteria" for a class-action lawsuit. However, the court did not rule on whether or not the cookware is safe, the attorney noted.

Thomas L. Sager, senior vp and general counsel for DuPont, said the ruling shows that Teflon "is safe for its intended use."

"Teflon is a trusted brand and is used all over the world by millions of people every day," he added.

A ruling denying the status was appealed to the 8th U.S. Circuit Court of Appeals, which refused to reconsider the lower court's ruling.