Dispersive liquid-liquid microextraction and Monte Carlo simulation of margin of safety for octocrylene, EHMC, 2ES, and homosalate in sunscreens.

Dispersive liquid-liquid microextraction (DLLME) using floating organic drop has been optimized and used for the sample preparation of four commonly used ultraviolet filter (UVF) substances in sunscreens. Plackett-Burman experimental design was used to screen ten variables in DLLME. The most significant variables were then optimized by using response surface methodology with a Box-Behnken design. DLLME followed by an optimized HPLC identified octocrylene (OC), 2-ethylhexyl-4-methoxycinnamate (EHMC), ethylhexyl salicylate (2ES), and homosalate (HMS) as frequently found UVFs in commercial sunscreens. The systemic exposure dosage (SED) and Margin of Safety (MoS) for identified UVFs were estimated using in-use concentrations and application patterns. The average SED values for OC, EHMC, 2ES, and HMS were 0.52, 0.61, 0.020 and 0.079 mg/kg·bw/day, respectively. While the average MoS values for individual UVFs ranging from 296 to 3160 were all significantly higher than the limit value of 100, the combined exposure risks were slightly above the limit. The probabilistic health risk assessment with Monte Carlo simulation revealed that the combined MoS values were (mean, 10%ile, 90%ile) 342, 119, and 441, respectively. Regarding the usage of sunscreen cosmetics containing the UVFs studied, these results indicate a safety concern for those who apply multiple UV filter products.