Over the counter and prescription benzoyl peroxide acne treatments may contain hazardous levels of benzene, raising concerns about cumulative risk.
Researchers analyzed 111 benzoyl peroxide (BPO) products and detected benzene concentrations ranging from 0.16 to 35.30 ppm, with 34% of products exceeding the FDA's conditional limit of 2 ppm for benzene products, according to results published in The Journal of Investigative Dermatology. Benzene levels were found to vary significantly between brands and product types within brands.
An encapsulated BPO prescription product (Epsolay) formed high levels of benzene at elevated temperatures, reaching 130 ppm after 2 weeks at 50°C. However, no benzene formation occurred when the product was stored at 2°C, suggesting cold storage may prevent formation.
Ultraviolet exposure accelerated formation. In a face model experiment, exposure to UVA/B light—simulating one-third of peak ambient sunlight—led to rapid formation in a BPO product, with about 4.36 ppb of benzene generated per 1 hour of exposure. This equated to 14.7 μg of benzene evaporating into the air after 2 hours.
When exposed to UVA/B light at 1,800 to 2,000 μW/cm², benzene rapidly formed in the chamber. Without UV exposure, benzene levels in the air increased from 1.96 ppb in the first 15 minutes to 4.31 ppb in the last 15 minutes over a 24-hour period.
The researchers also noted that two products tested past their expiration date had variable benzene levels, with one product showing significantly elevated levels.
Further studies and potential regulatory actions to address the issue were recommended.
Conflict of interest statements can be found in the study.