Phototoxic risk assessment on benzophenone UV filters: In vitro assessment and a theoretical model

Benzophenones (BPs), filtering out both UVA and UVB rays, are widely used in a great variety of sunscreens and personal care products. However, they have not been extensively studied for the mechanisms of UV-absorbing toxicity. In this study, we used CPZ (chlorpromazine) as a positive control and SDS (sodium dodecyl sulfate) as a negative control, and the phototoxic of BP-1, BP-3 and BP-4 were investigated in vitro assays using three cell types under different UV exposure conditions. This was followed by setting up a theoretical model, which was adopted to predict and compare the phototoxicity. It was found that Balb/c 3T3 (Balb/c 3T3 fibroblast cell lines) showed sensitivity to UVA+ and UVB+ exposure, while the HS68 (human HS68 fibroblast cell lines) to UVA+ and the HaCaT (human HaCaT keratinocyte cell lines) to UVB+. The test compound, BP-1, was detected to be phototoxic at UVA+ conditions, but BP-3 and BP-4 were discovered to be non-phototoxic at UVA+ conditions. This demonstrated that BP-1, BP-3 and BP-4 remained low-risk chemicals under UVB+ condition. The theoretical calculation of the energy gap (E_GAP) showed BP-1(E_GAP) > BP-3(E_GAP) > BP-4(E_GAP).