Risk assessment of benzophenone-3, a UV filter in cosmetics

Benzophenone-3 (also known as oxybenzone) is an ultraviolet filter commonly used in sunscreen formulations and personal care products. Given its systemic exposure through dermal and oral absorption, the toxicity of benzophenone-3 has been widely studied. In rodents, dietary exposure to high experimental doses of benzophenone-3 was associated with mild systemic toxicity, including reduction in body weight gain, increase in liver and kidney weights, and signs of nephropathy. While benzophenone-3 was shown to be non-irritating and non-skin sensitizing following ocular instillation and dermal application in animal studies, it has been recognized as a cause of photoallergic contact dermatitis in clinical studies. Mild reproductive and developmental effects have also been reported, including reduced offspring body weight, slightly reduced litter size, and altered sperm parameters. Benzophenone-3 was non-mutagenic in genotoxicity assays, and a lifetime dietary exposure study in rodents suggested equivocal evidence of carcinogenic activity. The endocrine-disrupting potential of benzophenone-3 is of concern because it binds to estrogen receptors. Although in vitro and in vivo assays have shown inconsistent results, the potential risk to humans remains a concern. For the safety assessment, a no-observed-adverse-effect level of 1,000 ppm (67.9 mg/kg/day) was selected from a reproductive and developmental toxicity study in which a reduced number of spermatocytes per seminiferous tubule was observed in male F1 offspring. The systemic exposure dose, calculated based on the daily usage amount for the Korean population, was 0.6732 mg/kg/day when used at 2.4% in sunscreen products, resulting in a margin of safety for benzophenone-3 that was approximately equal to or greater than 100. Therefore, the use of benzophenone-3 in cosmetics under current regulations is considered safe.