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In a Lather Over Triclosan? Thumbs Down to Fear-Mongering Soap Operas

Stop carrying on so we can stay calm posterAnother day, another fuss about an animal study. This time, it’s a cancer scare around a common antibacterial in soaps: triclosan.

“The dirty side of soap,” says the headline on the university’s press release. “Triclosan, a common antimicrobial in personal hygiene products, causes liver fibrosis and cancer in mice.” The title of the journal article it’s promoting? The commonly used antimicrobial additive triclosan is a liver tumor promoter.

That’s marketing hype. The research in this article simply does not have the weight to carry such strong assertions. But statements like these are enough to set off cancer scares. Ed Yong tweeted about this one, “I think it’s a disservice to cancer patients…(P)eople start thinking ‘My [loved one] got cancer. Is it my fault for buying so much hand soap?’ etc.”

I share his frustration with the way weak evidence gets seized upon by people trying to get attention. And within it is the frustration that it’s so easy to flick this switch. Those of us in developed countries are living longer, healthier lives than any humans ever have. Yet we’ve developed some kind of communal anxiety order. And among us are any number of people wanting to trigger that anxiety for reasons of their own, not our interests.

It could be researchers trying to stand out from their peers, or trying to get people to care more about the disease (or whatever else) they study. For them and their institution, arousing interest and concern might be the pathway to more funding and support for their work – and perhaps to satisfy the desire for recognition and any status that visibility in the public square provides.

Don't panic flag from Towel Day
Message from the Hitchhiker’s Guide to the Galaxy: Towel Day (Image by Ammit, via Wikimedia Commons)

It could be a patient or community affected by the problem. Awareness-raising can spring from the place of wanting to help others avoid the worst themselves, or be more supportive to those who are affected. But it’s a pathway to more funding, too.

Then there are professions, that may have seen almost no limits to the expansion of awareness, without thinking through necessarily, the social and psychological impact of turning us into the “worried well.” Without perhaps understanding fully, either, the impact on us of using fear to motivate – and the risk of “crying wolf” so often we all get a kind of alarm fatigue.

There are the industries with things to sell that depend on making us anxious. And of course there are the journalists, bloggers, and the rest of the media trying to get an audience, to get people to click, to keep reading, to read their next story and keep that news cycle going as long as possible.

When it comes to threats to health and safety, crossing the line into fear-mongering comes pretty quickly. There’s no proportion in this battle for hearts and minds. The “awareness-raising” doesn’t get dialed back when the community’s fears are out of proportion to the actual threat. Unless, that is, it tips over into major and very obviously destructive patterns – like the recent Ebola panic, or the autism scares around vaccines.


Cartoon of a lab rat who cannot fathom odd human logicSo what about these stories about soap this week? According to one of the authors, “We aren’t saying that triclosan causes cancer.” But that’s not what their press release said. And the distinction of promoting versus causing was lost by many.

They did 2 experiments – all in male mice, because they judged them more likely to get liver cancer. One involved only 12 mice – and its findings did not suggest that triclosan could cause cancer.

The other experiment had more mice, but was still small. The mice weren’t just exposed to far higher amounts of triclosan than would normally be encountered: cancer was induced separately. And the cancer in the ones who had triclosan progressed further – it promoted, but didn’t cause cancer. And it did so in the presence of something else. (More detail in my comment on PubMed Commons.)

These results on their own are not enough to tip the scale against the usual uses of triclosan. They are not definitive about the impact in mice, much less humans. The results of animal experiments do not translate to humans most of the time. (You can read more about why in my post at Statistically Funny.)

Is triclosan a good idea to have in soap? Probably not: it may not be particularly helpful – and overuse of antibacterials might turn out to contribute to resistance. But should you be worried that you may have cancer because of your soap? Not because of this research.

[Update 3 September 2016]: The FDA banned the sale of antibacterial soaps with some ingredients, including Triclosan, because “longterm exposure…could pose health risks, such as bacterial resistance or hormonal effects”.


Optical illusion

See also my post on 5 Shortcuts to Keep Data in Risks in Perspective: and my posts on risk-related themes are in this Storify theme index.

For the other side of the coin, try Resveratrol Hangover: Waking Up After Hypothesis-Bingeing.

The cartoons in this post are my own (Creative Commons License): more at Statistically Funny.

Here’s an explanation of “Don’t Panic” in the Hitchhiker’s Guide to the Galaxy – and the Towel Day that celebrates the author, Douglas Adams (photo by Ammit, via Wikimedia Commons).

* The thoughts Hilda Bastian expresses here at Absolutely Maybe are personal, and do not necessarily reflect the views of the National Institutes of Health or the U.S. Department of Health and Human Services.

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