A St Louis jury has awarded more than $6 billion ($US4.7 billion) in total damages to 22 women and their families after they claimed asbestos in Johnson & Johnson talcum powder contributed to their ovarian cancer, in the first case against the company that focused on asbestos in the powder.

Key points:

• Johnson & Johnson said the verdict was the result of an unfair process
• Medical experts testified that asbestos was intermingled with mineral talc
• Six of the 22 plaintiffs in the latest trial have died from ovarian cancer

The jury announced the $5.6 billion ($US4.14 billion) award in punitive damages shortly after awarding $742 million ($US550 million) in compensatory damages after a six-week trial in St Louis Circuit Court.

Johnson & Johnson called the verdict the result of an unfair process that allowed the women to sue the company in Missouri despite most of them not living in the state.

The company has said it would appeal, as it has in previous cases that found for women who sued the company.

"Johnson & Johnson remains confident that its products do not contain asbestos and do not cause ovarian cancer and intends to pursue all available appellate remedies," spokeswoman Carol Goodrich said.

Mark Lanier, lead counsel for the plaintiffs, said in a statement that Johnson & Johnson had covered up evidence of asbestos in its products for more than 40 years.

Medical experts testified during the trial that asbestos, a known carcinogen, is intermingled with mineral talc, which is the primary ingredient in Johnson & Johnson's Baby Powder and Shower to Shower products.

The plaintiffs' lawyers said asbestos fibres and talc particles were found in the ovarian tissues of many of the women.

"We hope this verdict will get the attention of the J&J board and that it will lead them to better inform the medical community and the public about the connection between asbestos, talc, and ovarian cancer," Mr Lanier said.

"The company should pull talc from the market before causing further anguish, harm, and death from a terrible disease."

During closing arguments, Mr Lanier told the jurors this case was the first where jurors saw documents showing that Johnson & Johnson knew its products contained asbestos and didn't warn consumers, The St Louis Post-Dispatch reported.

The company has been sued by more than 9,000 women who claim its talcum powder contributed to their ovarian cancer.

Johnson & Johnson has consistently denied that its products can be linked to the cancer.

Photo: One of the plaintiffs, Gail Ingham, was diagnosed with stage-3 ovarian cancer in 1985. (AP: Christian Gooden/St Louis Post-Dispatch)

Ms Goodrich said the verdict awarding all the women the same amount, despite differences in their circumstances, showed evidence in the case was overwhelmed by prejudice created when so many plaintiffs are allowed to sue the company in one lawsuit.

"Every verdict against Johnson & Johnson in this court that has gone through the appeals process has been reversed and the multiple errors present in this trial were worse than those in the prior trials which have been reversed," she said.

Lawyers for the plaintiffs said punitive damage awards are limited by state law to five times the amount of compensatory damages awarded and defence lawyers probably would file a motion to reduce the award.

Six of the 22 plaintiffs in the latest trial have died from ovarian cancer.

Five plaintiffs were from Missouri, with others from states that include Arizona, New York, North Dakota, California, Georgia, the Carolinas and Texas.

One of the plaintiffs, Gail Ingham, 73, of O'Fallon, Missouri, told The Post-Dispatch that she was diagnosed with stage-3 ovarian cancer in 1985 and underwent chemotherapy treatments, surgeries and drug treatments for a year before being declared cancer free in the early 1990s.

Ms Ingham, who used baby powder for decades, said she joined the lawsuit because women who use baby powder "need to know what's in there. They need to know what's going on. Women need to know because they're putting it on their babies".

In 2016, an American jury awarded $US100 million to the family of a woman who died from ovarian cancer and blamed her death on Johnson & Johnson talcum powder.

But the Cancer Council of Australia has warned that women should not be alarmed by the decision, adding that evidence of a link was "slim at best".