Evaluation of Benzene Presence and Formation in Benzoyl Peroxide Drug Products.

The potent carcinogen, benzene, is a known degradation product of benzoyl peroxide (BPO) and was recently reported to form when BPO drug products, used for acne and rosacea treatment, are incubated at body temperature and elevated temperatures expected during storage and transportation. This study provides evidence for a wide range of benzene concentrations (0.16-35.30 ppm) detected by gas chromatography-mass spectrometry in 111 over-the-counter BPO drug products tested and maintained at room temperature. A prescription-encapsulated BPO drug product was stability tested at cold (2 °C) and elevated (50 °C) temperature, resulting in no apparent benzene formation at 2 °C and high levels of benzene formation at 50 °C, suggesting that encapsulation technology may not stabilize BPO drug products but that cold storage may greatly reduce benzene formation. Face model experiments where BPO drug product was applied to polymethyl methacrylate photoprotection test skin plates and benzene was detected in surrounding air by selected ion flow tube-mass spectrometry showed detectable benzene through evaporation and substantial benzene formation when exposed to UV light at levels below peak sunlight. Results suggest that potential benzene exposure from formation during BPO drug product use poses significant risks independent of the starting benzene concentration.