A Sioux Falls woman is accusing Johnson and Johnson and two mining companies of failing for decades to warn consumers about a link between ovarian cancer and talcum powder.

Deane Berg, 52, applied talc-based body powder to her perineum each day after showering from 1975 to 2007, she says in a federal lawsuit filed last week. She contracted ovarian cancer in 2006.

Berg maintains that talc caused her cancer and that the companies selling the mineral knew there was a risk but failed to warn the public.

"I feel like women have been kept in the dark about a known hazard," said R. Allen Smith, Berg's lawyer. "It's the classic definition of why we need product liability lawsuits."

Some studies have associated the regular use of talc in the genital area to an increased risk of ovarian cancer. The most recent came in 2008, when a study from Harvard University epidemiologist Margaret Gates suggested women who used the product once a week might increase their risk of contracting the disease by 36 percent. For daily users, the risk jumped by 41 percent.

However, some studies have suggested no association between talc use and ovarian cancer. The American Cancer Society calls the study results inconsistent but advises those with concerns to switch to cornstarch-based powders.

"While the findings aren't considered fact just yet by the American Cancer Society, studies do cause some concern," said Charlotte Hofer, South Dakota's American Cancer Society representative.

Berg and her lawyers are convinced there is a link. The lawsuit, filed in U.S. District Court in South Dakota, cites studies about a possible link from as long ago as 1982. While government health agencies in countries such as Great Britain have noted the possible risk, the topic has flown under the radar in the U.S., Smith said.

He's unaware of any other civil lawsuit against producers of talc-based products.

"This is the first case of its kind, to my knowledge," Smith said.

Companies that market talc-based products without a warning label are guilty of negligence, the complaint alleges, as are companies that mine and market the mineral. Johnson and Johnson, mining company Luzenac America and its parent company, RioTinto Minerals, are named as defendants.

"My first hope is that we can protect women and make them aware of this link," Smith said. "My second hope is that we can make the industry warn about the dangers of their products."

The lawsuit seeks damages to pay for Berg's two years of cancer care and emotional damages.

Johnson and Johnson representative Bonnie Jacobs wouldn't comment on the case.

Calls to Rio Tinto's headquarters were not returned, but the Web site for Luzenac links to a study that questions any correlation between talc and cancer risk.

The federal government's National Cancer Institute Web site says the use of talc near the vaginal area could increase a woman's risk of ovarian cancer. Similar warnings appear on the sites of the Illinois and New York state departments of health.

The South Dakota Department of Health's Web site does not mention talc. Spokeswoman Barb Buhler said findings are too inconclusive to warrant a state warning.

"The studies cited are small and are suggestive but not very definitive," Buhler said. "The exact cause of ovarian cancer isn't clear."

That could be a problem for Berg, according to Mark Arndt, vice president of the South Dakota Defense Lawyers Association.

Smith, a Mississippi lawyer, is working the case with Rapid City's Gregory Eiesland and fellow Mississippian Tim Porter.

To win a judgment in a product liability lawsuit, Arndt said, they will need to do more than persuade a jury there is a scientific link between talcum powder and cancer.

"To win anything in this lawsuit, she's going to have to prove that talcum powder caused her cancer," Arndt said.

The lawsuit does not point to any physician's finding, however. It cites several studies, but without testimony from a doctor who treated Berg, Arndt said, it could be difficult to show causation.

But even if Berg's lawsuit fails for lack of conclusive data, Arndt said, there is a possibility it could focus attention on the issue and lead scientists to seek more definitive research.

The link between tobacco and cancer wasn't always clear, he said.

"Somebody had to start the tobacco lawsuits. Somebody had to start the asbestos lawsuits," he said. "It's hard to just dismiss it out of hand."