Wednesday, October 05, 2022

Like most people, I have a memory of my mother putting baby powder on me as a child after a bath—a warm, comforting nostalgic memory. Baby powder is also widely used by adults, especially women, as a drying agent over many parts of the body, but especially the genital area.

This powder consists primarily of talc, which is a clay mineral that is composed of magnesium silicate and is generally obtained from mines. It occurs in nature in proximity to asbestos, which it resembles in some ways; hence there have been some reports that it may cause lung cancer. An evaluation by the International Agency for Research on Cancer (IARC) as early as 1987 did mention at least one study showing an increase of lung cancer in one study of those who were occupationally exposed to talc.

So why was there concern raised about talcum powder, the primary form of baby powder used in the past? There were several reasons. One was a concern in the 1970s that there was silica in some of the powders and that the powder could be inhaled, leading to pulmonary scarring or lung cancer. Until then no issues had been raised with regard to gynecologic cancers. The person who brought that to light was Daniel Cramer, a cancer epidemiologist at the Brigham and Women’s Hospital in Boston who specializes in gynecologic malignancies. He and his colleagues conducted a case-control study that collected 215 ovarian cancer cases from 12 hospitals in Boston between 1978 and 1981. Controls were selected from the general population and matched to the cases on age, neighborhood, and race. Ninety-two of the cases (42.8%) reported the use of talcum powder regularly in the genital area versus 61 (28.4%) of the controls for a risk ratio of 1.92 (p>0.003).

This study received widespread attention. Multiple further studies were then conducted that, more or less, replicated these findings. One such study was the New England Ovarian Cancer Study, which compared 2,041 women with ovarian cancer living in Massachusetts or New Hampshire to 1,578 women without cancer. The relative risk was about 1.33 in this particular study.

At least 15 studies were done, most of them showing a similar increased risk. A meta-analysis (combination of all the studies and estimation of an average risk ratio) suggested a summary relative risk of about 1.3, consistent with a causal association.

Of course, there are also counter-arguments to be made. The exposure information in all of these studies is derived from individual self-report regarding the use of baby powder. As one may imagine, this can be notoriously unreliable, and there is no objective way to validate it.

After Cramer’s first positive report in 1982 and the publicity it generated, the sales of talcum powder products in the U.S. declined dramatically, signaling widespread concern. One of the best known biases in epidemiology is recall bias—the tendency of the subject with the disease to answer the exposure question in a different way than the control. One can hardly imagine a situation that would be more rife with this problem. And once it became clear that lawsuits would arise out of these studies, so-called litigation bias—the tendency for subjects with the disease to answer in a certain way so as to further a future lawsuit—became even more of a problem in the interpretation of study results.

Another problem is the inconsistency of the findings. Why would talc cause cancer in the ovary when it does not apparently cause lung cancer?

Another problem is the fact that talc is used in other ways than solely by the administration of baby powder. It is used on diaphragms as well as on condoms. Thus, exposure to talc proceeds through other sources than solely baby powder. Several studies have investigated whether talc exposure through these alternative routes increased the risk of ovarian cancer. All of them have proven negative.

What does seem to have clinched the issue is the finding in 2019 of asbestos contamination in samples from the Johnson & Johnson baby powder commercial products. This gave a plausible explanation to the mechanism of carcinogenicity. A follow-up evaluation by IARC in 2020 concluded that there was sufficient reason to believe that talc contaminated by asbestos was indeed a causal agent in inducing ovarian cancer.

And as could be expected, all of this did indeed lead to massive litigation. The most prominent lawsuit was led by Mark Lanier of Houston, one of the best-known mass tort attorneys in the U.S., who brought suit against J&J for 22 women with ovarian cancer and won a $4.69 billion award (later reduced to $2.1 billion), claiming that J&J knew about the asbestos contamination for years. The lawsuits are ongoing.

Alfred I. Neugut, MD, PhD, is a medical oncologist and cancer epidemiologist at Columbia University Irving Medical Center/New York Presbyterian and Mailman School of Public Health in New York.

This article is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment, and does not constitute medical or other professional advice. Always seek the advice of your qualified health provider with any questions you may have regarding a medical condition or treatment.

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