Study of the photolysis and cellular toxicity of the organic ultraviolet filter chemical 3-(4-methylbenzylidene) camphor and its photoproducts

Organic ultraviolet filter chemicals (UVFCs) are a major class of chemicals found as the active ingredients in personal care products, most commonly in sunscreens, cosmetics, and lip balms, where their purpose is to protect the skin from UV radiation. These UVFCs pose potentially harmful effects, both to human health and to the environment. One such example of a UVFC is 3-(4-methylbenzylidene) camphor. Also known as 4-MBC, 3-(4-methylbenzylidene) camphor is a camphor derivative and classified as an organic UV-B filter chemical. Interestingly, 4-MBC is not one of the 16 chemicals currently allowed by the FDA as an active ingredient in sunscreens, but it is often listed as an inactive ingredient despite the lack of knowledge regarding 4-MBC currently. Thus, the goal of this research was to study 4-MBC to learn more about the UV filter chemical and its photoproducts. An Atlas Suntest XLS+ solar simulator, high performance liquid chromatography, liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy were used to investigate the kinetics of 4-MBC photolysis alone and in the presence of humic and fulvic acids. Further, the cellular toxicities were determined for 4-MBC and its photoproducts. With this new-found information, we can better access the suitability of 4-MBC as an inactive ingredient in personal care products to ensure safety standards are met for human health, as well as environmental protection.