NEW YORK (Reuters) - A lawsuit by 22 ovarian cancer patients against Johnson & Johnson went to trial on Wednesday in Missouri state court, marking the largest case the company has faced over allegations its talc-based products contain cancer-causing asbestos.

FILE PHOTO: A Johnson & Johnson building is shown in Irvine, California, U.S., January 24, 2017. REUTERS/Mike Blake/File Photo

The women and their families suing in the Circuit Court of the City of St. Louis say decades-long use of J&J’s Baby Powder and other cosmetic talc products caused their disease. They allege the company knew its talc was contaminated with asbestos since at least the 1970s but failed to warn consumers about the risks.

J&J denies both that its talc products cause cancer and that they ever contained asbestos.

J&J is battling some 9,000 cases brought by users of its Baby Powder and Shower to Shower talc products, the latter of which was sold to Valeant Pharmaceuticals [VAPI.UL] in 2012.

The majority of those lawsuits claim talc caused ovarian cancer in women who used it for feminine hygiene. A smaller number of cases allege talc contaminated by asbestos in the mining process caused mesothelioma, a tissue cancer closely linked to asbestos exposure.

The cases that went to trial on Wednesday effectively combine those claims by alleging the women’s ovarian cancer was caused by asbestos in J&J talc products.

J&J lawyer Peter Bicks told the jury on Wednesday that the causes for ovarian cancer are often unknown, according to an online broadcast of the trial by Courtroom View Network.

He said gene mutations and a family history of cancer played an important role and that asbestos was not known to cause ovarian cancer.

Bicks added that testing done by independent laboratories, universities, government agencies, talc suppliers and J&J itself has shown that there is no asbestos in the company’s talc.

But plaintiff’s lawyer Mark Lanier said asbestos and talc, which are closely linked minerals, are intermingled in the mining process, making it impossible to remove the carcinogenic substance. Lanier said there was “no doubt” that talc caused his clients’ ovarian cancer.

“This case is as simple as asbestos breathed in or put inside of you,” Lanier told the jury.

J&J has lost two talc mesothelioma jury trials in the past weeks. Those cases are currently under appeal.

Juries in California and Missouri have also issued verdicts in ovarian cancer cases totaling more than $720 million in damages. Those decisions have either been tossed out or are still under appeal.