By Dietrich Knauth

July 22 (Reuters) - A federal judge cast doubt on Wednesday on claims by approximately 69,000 people alleging that Johnson & Johnson’s (JNJ.N) baby powder and other talc products caused ovarian cancer, saying plaintiffs must provide more specific evidence or risk having their lawsuits dismissed.

U.S. Magistrate Judge Rukhsanah Singh in Trenton, New Jersey, said that recent testimony by two of the plaintiffs’ experts raised doubts about whether any plaintiffs can provide evidence admissible in court “that talcum powder use specifically caused her ovarian cancer.”

The two experts, Judith Wolf and Daniel Clarke-Pearson, testified in May in preparation for a set of six “bellwether,” or test, trials for the thousands of court cases that have been consolidated in New Jersey’s federal court. Verdicts in bellwether trials are used to assess the potential value of remaining claims and guide settlement talks.

J&J has denied the allegations that its talc products caused cancer, saying that talc was safe and did not contain asbestos.

A spokesperson for the company did not immediately respond to a request for comment, nor did a lead attorney for the plaintiffs.

Wolf and Clarke-Pearson said they could not completely rule out other possible causes of the plaintiffs’ ovarian cancer, according to Singh’s opinion.

“If such uncertainty is indeed reality, then how can any plaintiff here meet her burden on the merits of her claim?” Singh wrote.

Singh said that the debate over causation would not lead to “instant dismissal” of the thousands of cases in the consolidated federal litigation. The judge ordered plaintiffs to respond by November 19, and to explain why their case should not be dismissed over the failure to provide an admissible expert opinion that J&J talc caused their specific cancer.