Cancer photo
Flickr user Mike Mozart

The signature smell is hard to forget. Johnson and Johnson’s baby powder, a product that was once considered simple, benign, and ubiquitous among new mothers is now the subject of intense legal allegations. Over the past several years, the company has been struggling with claims that its powder, the main ingredient in which is talc, caused ovarian cancer in a number of women who had used the product for years. In July, Johnson and Johnson paid a group of plaintiffs $4.69 billion for the damage.

Most recently, this past week, Reuters reported that Johnson and Johnson had known since the 1970s that its baby powder might have contained or been contaminated with small amounts of asbestos, a known carcinogen.

But how talc, asbestos, and cancer all connect together is a far more complicated web to weave—and unravel.

What is talc—and how is it related to cancer?

Talc is a natural mineral found in metamorphic rocks around the world. The mineral is among the softest materials in the world so when ground into a powder, called talcum powder, it’s superb at absorbing moisture and reducing friction, and thus, helping to prevent diaper rash as well as chafing and other skin irritations.

In the United States, most deposits collect on the eastern side of the Appalachian mountains and in parts of the northwest and New Mexico. The substance is most often collected from open pit mines by drilling, blasting, and crushing the metamorphic rock material. Because talc isn’t the only substance found within these rocks, there’s a chance that the mined talc can be contaminated with other substances.

As it happens, talc and asbestos occur naturally together. And that’s a problem, because asbestos is a known carcinogen. It was often used in insulating buildings because of its strength and heat-resistant properties. But in the early 20th century, once it became clear that exposure to high levels scarred lungs, the substance was banned from use in construction materials.

Exposure to large amounts of asbestos, especially over long periods of time, has clear and documented health effects. But the asbestos exposure experienced by regular talc users is on an entirely different order. Women who used baby powder over a lifetime had trace exposure, but dosed out over decades. How that kind of slow-grade asbestos release affects human health is far less established.

Did the baby powder contain asbestos?

One of the main claims made against Johnson and Johnson’s baby powder was from women who used the talc powder routinely for feminine hygiene and claimed that routine exposure to the asbestos-laden product caused ovarian cancer. Back in July, a jury agreed with them, forcing Johnson and Johnson to over four billion dollars in damage.

But a jury’s verdict isn’t the same as a scientist’s. The big unknowns in this case were whether the product actually contained asbestos, and if it contained it in amounts that were high enough to cause cancer.Neither question can be answered in a clear-cut manner.

The recent Reuter’s report suggests that once it became clear that talc could be laced with asbestos, and that asbestos was an established carcinogen, Johnson and Johnson should have openly communicate results of internal testing on the amount of asbestos in its powder to both the FDA and the public, but they failed to do so.

What is the FDA’s role?

According to The New York Times, the FDA last tested commercial products that contain talc for asbestos back in 2010 and found no trace elements. However, private experts on behalf of lawyers for plaintiffs, have done independent tests and did detect asbestos in the talc products.

Routinely, the FDA does not test consumer products for safety. Because they are not prescription drugs and are not claiming to treat or cure a condition, these products do not need to comply with the same safety regulations as pharmaceuticals. Rather private companies typically comply with the Personal Care Products Council, which has stated that all talc products should be free of asbestos since 1976.

A major reason that none of this is clear cut is that it’s incredibly difficult to link the trace levels of asbestos in the amount that would be found in talc to cancer. Asbestos was originally tagged to cancer in relation to coal miners and construction workers who were exposed at far higher levels, often breathing in dusty air that contained the substance.

But the amount of the substance required to start cancer growth is near impossible to pin down. For example, research on the connection between ovarian cancer and the frequent and long-term use of talc-containing powder on the genitals has shown varied results, with some showing a slight increased risk and others showing no association at all. Further, as the American Cancer Society (ACS) points out, many of these studies are further complicated by the fact that the studies often rely on participants to recall years later exactly how much talc powder they used often years or decades earlier. Both the National Cancer Institute and the ACS conclude that research is ongoing and that any evidence of a connection—the strongest of which would be a very, very small increased risk— isn’t strong enough yet.

As PopSci reported back in August, this becomes even more complicated when you factor in how decisions about these connections are made by juries in a courtroom. A jury merely has to decide between two conclusions: Whether it’s more likely that talc caused the cancers or that it didn’t. Science, on the other hand, has a far higher bar to meet, and must be able to show, with high statistical certainty, that it’s nearly impossible that anything else could have caused the cancer other than the talc powder, which in many cases is near impossible to do.

Is baby powder actually useful for babies or adults?

For all it’s hype, baby powder is likely not worth the risk, talc aside. According to the Times, because of the risk of an infant choking on the powder, the American Academy of Pediatric recommends against using talc powders, and instead using an oil-based ointment, if necessary. For adults, a cornstarch-based powder is a good alternative for skin irritation or chafing.