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 (p_c) at the air-sweat interface on human skin surface must be examined. This study analyzed the p_c 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 p_c during human dermal exposure to gaseous VOCs. The salt effect resulted in increase of p_c for hydrophilic and hydrophobic VOCs, and the dissolved VOC concentration effect resulted in a reduction in p_c, which is dominant for hydrophilic compounds of high concentrations of aqueous VOCs. The p_c data were utilized for further assessment of risk due to dermal exposure to VOCs.

Keywords:

• Volatile organic compound
• skin
• exposure
• sweat
• partitioning equilibrium

Acknowledgments

The authors would like to thank the National Science Council, Taiwan, Republic of China, for financially supporting this research under contract Nos. NSC 94-2211-E-242-002 and NSC 95-2815-C-242-001-E.