If you've been reading recent media reports, you might have found yourself asking if it's safe to use talcum powder.

A recent Reuters investigation of company memos, internal reports and other confidential documents showed Johnson & Johnson knew for decades about the presence of small amounts of asbestos in its products dating back to as early as 1971.

The company has forcefully denied the media report, saying that "any suggestion that Johnson & Johnson knew or hid information about the safety of talc is false".

Earlier this year, a St Louis jury awarded more than $US4.7 billion ($6 billion) in total damages to 22 women and their families after they claimed asbestos in J&J talcum powder contributed to their ovarian cancer.

So we asked an expert from the Cancer Council of Australia what they think of the evidence that's out there and if you should stop using it.

How is talcum powder made?

Talc, which is used in J&J's baby powder according to its website, is the softest mineral on earth.

There are different types of talc, including industrial and cosmetic-grade, which is used in a variety of products.

According to the Cancer Council of Australia, in its natural form, some talc may contain asbestos, which is known to cause cancer.

That's because geologically, talc and asbestos can naturally form alongside each other. But not every talc deposit is contaminated with asbestos.

Questions were raised in the 60s about links between workers exposed to talc and ovarian cancer after researchers found that asbestos could cause cancer of the lungs and pleural cavity (the lining of the lungs), chair in health effectiveness for the UK Andrew Watterson wrote for the Conversation.

But since the 1970s, pharmaceutical talc — and hence commercial — products have gone asbestos-free.

Is there a link between talcum powder and cancer?

According to the Cancer Council of Australia, in its natural form, some talc may contain asbestos, which is known to cause cancer. ( Flickr: Shaun Murphy )

Professor Bernard Stewart, a scientific advisor for Cancer Council, says the evidence that talcum powder does cause cancer is "very slight indeed".

"There is no definitive evidence that it does, in the sense that there is definitive evidence that smoking causes lung cancer," he said.

"There is some data available in what are called 'case control studies,' where women with ovarian cancer were asked if they ever used talcum powder in the perianal region years ago … and there was some evidence there was an increased risk due to the use of talcum powder."

But Professor Stewart says that type of study is "not as definitive as cohort studies", where up to 1 million women are asked in a single go what their diet is, what their practices are in respect of personal products, etc.

"Then years later, amongst the million women, a few women are diagnosed with ovarian cancer and it's possible to take out the records," he said.

"When that sort of examination is done, no increased risk of ovarian cancer correlated with baby powder use was evident."

So, Professor Stewart says the risk, if it exists, "is far from established".

"It may not exist at all, or if it is there, we have yet to clarify it," he said.

"The risk is certainly not great enough for any health authority in the world, to my knowledge, to put warning labels on talcum powder or similar products, so that's a measure of the uncertainty — or some would say the evidence against the notion — that women using talcum powder are at an increased risk of ovarian cancer."

So is it safe to use on babies?

The evidence relates totally to adult women using the product. ( ABC North Queensland: Nathalie Fernbach )

Yes. Professor Stewart said there is no issue with babies in respect of cancer.

"In terms of the science and the possibility of causation of ovarian cancer, there is no evidence whatsoever in relation to the use by mothers on babies."

The evidence totally related to adult women using the product.

"The idea that there is some concern, or that people should be avoiding using baby powder on babies, is just out of the question so far as there is absolutely no evidence on that matter," he said.

And should people stop using it?

If you're worried, you can. But experts say there is no basis for anxiety in respect of past use.

"If an individual women says 'in light of the evidence, it may be uncertain but I'm not going to use talcum powder in that way,' she is certainly free to do so," Professor Stewart said.

"But there is no basis on which health authorities can say to women as a group, or as a population, 'look, to be on the safe side stop using this product in this way'."

But Professor Stewart said there are groups of women, particularly cancer survivors, who might recommend not using talcum powder in certain instances.

"And of course as ovarian cancer survivors it's their right to give this advice," he said.

"But generally speaking the scientific evidence has not warranted health authorities intervening either to put warning labels on the product or to advise the community as a whole not to use the product."

Currently, talcum powder is classified by the International Agency for Research on Cancer (IARC) as possibly carcinogenic (cancer causing) to humans when applied to the genital area.

IARC is a part of the World Health Organisation, which convenes international expert working groups to evaluate the evidence of the carcinogenicity of specific exposures.

And the Cancer Council says further research is needed to determine if there is a link between ovarian cancer and talcum powder.

The advice from Ovarian Cancer Australia is that women should avoid using talc-based products.

Should people be worried about past use?

Professor Stewart says based on the evidence, there is no reason for people to worry about past use.