Deodorants still don’t cause breast cancer

It was perhaps inevitable that a paper published in the journal Journal of Applied Toxicology that showed parabens (a preservative used in underarm deodorants and countless other products) to be present in breast cancer tissue samples would be grabbed by the tabloids and others and turned into the latest scare story about how deodorants cause breast cancer. Indeed The Daily Mail, for instance, not known for its scientific accuracy announced that: “Chemical found in deodorants, face cream and food products is discovered in tumours of ALL breast cancer patients”.

Of course, that wasn’t even close to the truth, the study tested samples from just 40 women who had had breast cancer mastectomy. All samples were found to contain parabens, but not all the women reported using underarm deodorants. It didn’t analyse the deodorants they actually used nor did it test 40 samples from women without breast cancer, nor did it even imply that parabens are linked to breast cancer.

However, The Sun, another notoriously sensationalist paper, quoted lead author of the paper, Philippa Darbre of the University of Reading as saying: “I ditched my deodorant to lower risk of breast cancer”. I spoked to Darbre and she confirmed that she had stopped using underarm deodorant 15 years ago. Some people switch to those so-called “natural” stone deodorants that are actually composed of aluminium salts to reduce sweating in the hope that they are safer. Aluminium salts inhibit sweating and are widely used in commercial anti-perspirants, but I think the toxicity of aluminium salts is even more prominent than parabens. Back in March 2006, I wrote about some of Darbre’s other work that looked into aluminium-containing deodorants and…you guessed it…breast cancer. If there were a link between deodorants and cancer risk maybe it could be in stifling the underarm sweat pores rather than some spurious chemical connection.

At the time Kat Arney, cancer information officer at Cancer Research UK told me that “…the main risk factors for breast cancer are age, reproductive history and a strong family history of the disease.” Other factors, such as excessive alcohol consumption, hormone replacement therapy, and menopause weight gain can also increase a woman’s risk of breast cancer. She adds that, “In the case of deodorants and breast cancer, there is little scientific evidence to link the two.” Others have confirmed this and NHS Choices says as much in its debunking of the latest tabloid nonsense about parabens.

Nothing’s changed. This latest paper seems to be just another iteration. I reported on Darbre’s earlier work on parabens for Spectral Lines (now SpectroscopyNOW.com) back in June 2004, but even by then there had been epidemiological studies dating back to 2002 that showed pretty much conclusively that there is no link. Indeed, studies show that if you test the urine of anyone in the west you will most likely get a positive for the presence of parabens.

I asked Colin Sanders a cosmetic chemist who blogs at Colin’s Beauty Pages, based in Petworth, UK, to comment on the issue of parabens and the reporting of the Darbre study. “Parabens are still the most widely used preservative in cosmetic and personal care products,” he told me. “If you launch a product that is going to sell millions of units you know that you are going to get a few people reporting allergic reactions. It doesn’t take long to notice that formulations preserved with parabens get fewer skin reactions than other preservatives.”

Sanders adds that, “Bizarrely enough, antiperspirants generally don’t need to be preserved. A few contain very low levels of parabens, but most don’t have any kind of preservative. It doesn’t seem very likely that they would cause breast cancer. A couple of them are weakly estrogenic. If they do indeed accumulate in breast tissue then that might be a cause for concern. Darbre’s work suggests they do [accumulate] but it has not yet been confirmed by any other group.”

He also suggests that there is a philosophical flaw in taking that approach to investigating the causes of breast cancer. “The trouble is that if you ask the question ‘are parabens safe?’ we don’t have enough information to say definitely yes. But that isn’t the question that the people researching cancer would ask. They would start by asking which factors are most likely to cause cancer. If you look at it from that point of view, what case is there for looking at parabens? Not very much really. There are stronger estrogen mimics that we are exposed to in much greater quantities, especially in food.”

Sanders adds that, “As a cosmetic chemist I would love parabens to be investigated more thoroughly. But if I was trying to reduce the incidence breast cancer I would have bigger fish to fry. It is easy to write a story knocking a particular chemical, but if that diverts research away from the most profitable areas to work in it could delay the development of effective treatment.”

Some chemicals are hazardous and definitely cause harm, the hepatotoxic volatile organic solvent ethanol, for instance, found in wine, beer and spirits. Similarly, the natural products of combustion of the dried leaves of Nicotiana tabacum are well known carcinogens. The tabloids will be tabloids. Take all they print with a pinch of salt…although not too much, mind you, it will make your blood boil!

Research Blogging IconBarr, L., Metaxas, G., Harbach, C., Savoy, L., & Darbre, P. (2012). Measurement of paraben concentrations in human breast tissue at serial locations across the breast from axilla to sternum Journal of Applied Toxicology DOI: 10.1002/jat.1786

You can read a more detailed discussion from yours truly in my latest Research Highlight article for the magazine Chemistry Views.

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