LOS ANGELES — Deane Berg’s doctor called her in the day after Christmas 2006 to give her the crushing news. She’d had her ovaries removed, the pathology results were back. Berg had stage III ovarian cancer, and her prognosis was poor.

Despite her 25 years as a physician’s assistant, Berg, then 49, knew next to nothing about ovarian cancer. Grappling with the “why me?” question, she reviewed the risk factors, finding just one that could apply: regular use of talcum powder for feminine hygiene.

Talc powder might be a cause ovarian cancer — who knew? Berg was stunned to learn that about 20 medical journal studies dating to the early 1980s had found women who regularly used talc powder for feminine hygiene had higher-than-average rates of ovarian cancer. Yet the evidence — which fell short of proving causation — was mostly confined to medical journals.

For millions of women, Berg included, dusting the genitals or underwear with powder was a daily ritual. Since her teens, Berg had used Johnson’s Baby Powder and Shower to Shower, another Johnson & Johnson powder marketed to women. “A sprinkle a day keeps odor away,” the ads said. “Your body perspires in more places than just under your arms.”

“This is crazy,” Berg recalled thinking. “Why aren’t they warning women about it?”

So after painful rounds of chemotherapy, Berg filed a first-of-its-kind lawsuit against Johnson & Johnson in federal court in her hometown of Sioux Falls, S.D. In a mystifying verdict in October 2013, the jury found Johnson & Johnson Consumer guilty of negligence for failing to warn of the ovarian cancer risk but awarded zero damages to Berg.

Yet the case brought a slow-building controversy to a head. Plaintiff lawyers have since brought claims for about 700 ovarian cancer victims or their survivors, blaming the disease on exposure to talc powder. Along with Johnson & Johnson, the suits name Imerys Talc America, part of the global mining concern that supplies talc. Other marketers of talc powder and the Personal Care Products Council, a Washington trade group for cosmetics makers, are named in some suits.

Imerys and the Personal Care Products Council wouldn’t comment. Johnson & Johnson said: “It is important for consumers to know that the safety of cosmetic talc is supported by decades of scientific evidence and independent peer-reviewed studies.”

The first trials are scheduled for early 2016.