Elevated Levels\nof Photoinitiators in Nail Salon Workers’\nHand Wipes and Occupational Risk Estimation

Photoinitiators (PIs) are widely used as chemical additives\nin\nvarious commercial products, including nail polishes, leading to major\nconcern with regard to occupational exposure. Herein, 27 PIs, including\n12 benzophenones, 8 amine co-initiators, 3 thioxanthones, and 4 phosphine\noxides, were analyzed in hand wipes from nail salon workers and controls.\nTwenty-four PIs were identified in hand wipes collected from nail\nsalon workers, with concentrations ranging from 133 to 5.06 ×\n10<sup>4</sup> ng/wipe (median: 4.26 × 10<sup>3</sup> ng/wipe),\nwhich were significantly higher than those of control workers (median:\n59.4 ng/wipe). Particularly, 1-hydroxycyclohexylphenylketone (median:\n1.27 × 10<sup>3</sup> ng/wipe) and 2,4,6-trimethylbenzoyldiphenylphosphine\noxide (median: 2.20 × 10<sup>3</sup> ng/wipe) were the most abundant\ncongeners in hand wipes of nail salon workers, respectively contributing\n42% and 57% to the total PI concentrations. An artificial skin model\nexperiment found that 3–30% of PIs on human skin could be absorbed\nby human bodies. The estimated daily intakes, based on median concentrations\nfor nail salon workers via dermal and hand-to-mouth contacts, were\n5.17 and 0.32 ng/kg bw/day, respectively, significantly higher than\nthose of the general population. This is the first study investigating\nPIs on human hands, providing solid evidence of dermal exposure to\nPIs for nail salon workers and the general population.