Ultraviolet (UV) radiation from the sun is an important environmental factor that affects human health. Organic UV filter chemicals are active ingredients in sunscreen that absorb UV light in order to protect the skin from damage. Octyl methoxycinnamate (OMC) is one common UV filter chemical found in sunscreens and other cosmetic products. In both sunscreen formulations and in aqueous solution, upon exposure to UV light, OMC readily degrades to form photoproducts, which have different photoreactivities. In addition to a lack of photostability, OMC, as well as other UV filter chemicals, are readily absorbed through the skin. OMC has been detected in the urine, blood, and breast milk of humans. The presence of OMC in bodily fluids has spiked an interest in determining the toxicity of both OMC itself and its photoproducts. Our research aims to identify and characterize the photoproducts of OMC and to determine the cellular toxicity of OMC and its photoproducts. To identify photoproducts, both aqueous solutions of OMC and commercial sunscreens containing OMC were exposed to simulated sunlight in a solar simulator; the photolysate was analyzed by high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS). While it was found that OMC degrades slower in the sunscreen than in the aqueous solution, there is evidence of photoproduct formation in both. The photoproducts include 4-methoxybenzaldehyde, 2-ethylhexanol and OMC dimers. Ongoing work is focused on investigating the cellular toxicity of OMC and its photoproducts. This is done by incubating NIH/3T3 cells (a mouse fibroblast cell line) with OMC and identified photoproducts at varying concentrations and subsequently assessing the viability of these cells using the neutral red assay. The results of this research help us better understand the photodegradation of OMC both in water and in commercial sunscreen products, as well as the toxicity of OMC and its photoproducts.

Photolysis and toxicity of the organic UV filter chemical octylmethoxycinnamate and its photoproducts

249th National Meeting (2015)

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