Dissolved VOC concentrations and salt contents affecting air-sweat equilibrium partition of hydrophilic and hydrophobic VOCs

Abstract

Workers have frequently disregarded long-term dermal exposure to low concentration of gaseous volatile organic compounds (VOCs). To assess dermal exposure risk to gaseous VOCs, equilibrium partitioning coefficients (pc) at the air-sweat interface on human skin surface must be examined. This study analyzed the pc values of hydrophilic iso-propanol (IPA), methyl ethyl ketone (MEK), and hydrophobic benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene (BTEXs) at the air-water and air-sweat interfaces at 27–47°C. The hydrophilic VOCs were dissolved in pure water and artificial human sweat liquors at approximately 10–125 mg/L, and hydrophobic VOCs were at approximately 0.55 mg/L. According to experimental results, the dissolved VOC concentration and salt contents simultaneously have a co-effect on pc during human dermal exposure to gaseous VOCs. The salt effect resulted in increase of pc for hydrophilic and hydrophobic VOCs, and the dissolved VOC concentration effect resulted in a reduction in pc, which is dominant for hydrophilic compounds of high concentrations of aqueous VOCs. The pc data were utilized for further assessment of risk due to dermal exposure to VOCs.