Elevated Levels of Photoinitiators in Nail Salon Workers’ Hand Wipes and Occupational Risk Estimation

Abstract

Photoinitiators (PIs) are widely used as chemical additives in various commercial products, including nail polishes, leading to major concern with regard to occupational exposure. Herein, 27 PIs, including 12 benzophenones, 8 amine co-initiators, 3 thioxanthones, and 4 phosphine oxides, were analyzed in hand wipes from nail salon workers and controls. Twenty-four PIs were identified in hand wipes collected from nail salon workers, with concentrations ranging from 133 to 5.06 × 10⁴ ng/wipe (median: 4.26 × 10³ ng/wipe), which were significantly higher than those of control workers (median: 59.4 ng/wipe). Particularly, 1-hydroxycyclohexylphenylketone (median: 1.27 × 10³ ng/wipe) and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (median: 2.20 × 10³ ng/wipe) were the most abundant congeners in hand wipes of nail salon workers, respectively contributing 42% and 57% to the total PI concentrations. An artificial skin model experiment found that 3–30% of PIs on human skin could be absorbed by human bodies. The estimated daily intakes, based on median concentrations for nail salon workers via dermal and hand-to-mouth contacts, were 5.17 and 0.32 ng/kg bw/day, respectively, significantly higher than those of the general population. This is the first study investigating PIs on human hands, providing solid evidence of dermal exposure to PIs for nail salon workers and the general population.