Beyond static loading: a dynamic, multifactorial assessment of dermal exposure to organophosphate esters

• This is the first study on dermal OPE exposure across a wide age spectrum. • Directly exposed skin areas showed higher OPE loads than clothed areas. • Youngest children aged 2 − 6 years exhibited the highest dermal OPE burden. • Dermal OPE loads were dynamically shaped by behavioral and physiological factors. • Health risk of OPEs via dermal contact was relatively low. Dermal contact is a significant yet underexplored pathway for human exposure to organophosphate esters (OPEs). This study provides a multifactorial assessment of dermal OPE exposure across participants aged 2 − 78 years by analyzing 29 OPEs in skin wipes from four body sites and personal smartphones. Results showed that directly exposed skin areas (hands, forehead, forearms) (range: below method detection limit (<MDL) − 5337 pg/cm 2 ) had significantly higher loads than clothed areas (back) (range: <MDL − 697 pg/cm 2 ). Children aged 2 − 6 years exhibited the highest dermal burden. A strong positive correlation linked skin OPE levels to those on smartphones, identifying phones as a key interface for OPE transfer to skin. Outdoor activity and lower body mass index (BMI) were associated with higher dermal loads, while exercise-induced sweating promoted OPE transfer to the skin surface. Calculated daily intake via dermal absorption was highest in young children (the total dermal exposure of OPEs: 3295 pg/kg bw/day), significantly exceeding that of older children and adults (837 − 1679 pg/kg bw/day). Although subsequent risk assessment indicated low carcinogenic and non-carcinogenic risks under current guidelines, the elevated exposure in vulnerable groups underscores the need for precautionary measures. These findings reveal dermal OPE exposure as a dynamic process shaped by behavior, physiology, and personal item use.