In this week's C&EN, this bit of news about recent Valisure findings (article by Craig Bettenhausen):
Concerns about benzene in personal care products are back, this time in acne medications based on benzoyl peroxide. Benzene is known to cause cancer in humans.
The independent analytical lab Valisure filed a petition last week asking the US Food and Drug Administration to recall and suspend sales of all benzoyl peroxide products. David Light, the firm’s cofounder and president, says his team found that the ingredient decomposes to benzene in consumer product formulas.
Valisure has found benzene in multiple consumer products in recent years, including hand sanitizer, sunscreen, dry shampoo, and aerosol antifungal medication. But in those cases, the benzene seems to have been a contaminant in the raw materials, and the findings were limited to certain batches and brands.
In acne products, Light says, the primary active ingredient breaks down into benzene under conditions that products might encounter in transport and in the home. The firm also found that the benzene diffused out of many of the bottles over time. “The evidence strongly shows us that this is a broad benzoyl peroxide problem,” he says. “We don’t have confidence on any product being immune at this point.”
Consumer product makers insist their acne medications are safe. Estée Lauder, which uses benzoyl peroxide in one Clinique-brand product, says it is “an FDA-approved and commonly used ingredient for acne treatment. . . . This product, like all of our products, is safe for use as intended.”
The industry’s criticism emphasizes storage conditions. Much of Valisure’s data documents the emergence of benzene over time in products held at 50 °C and 70 °C—temperatures that consumers are told to avoid. The label on the acne product Clearasil, for example, instructs consumers to store the product at room temperature away from bright light. And some prescription-strength benzoyl peroxide formulas are meant to be stored in the fridge.
I'm not an analytical chemist, so I have no idea whether or not their findings are correct. I am a (former) organic chemist, though, and I have a gut level skepticism that solid-ish benzoic acid radicals will undergo decarboxylation as opposed to (I dunno) abstracting a hydride from some other molecule in the formulation.
What is the literature around this? A brief Google search doesn't offer a lot of answers. If there is a raft of evidence of radical-initiated decarboxylation of benzoyl peroxide, maybe I might believe it, but I guess I'm still quite skeptical. (Don't forget that Light has patented a technology around this, so let's remember that (as always) there are conflict of interest concerns.)