Dermal absorption of dichloro- and trichloroacetic acids from chlorinated water

초록

Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are major nonvolatile disinfection by-products of water chlorination. These compounds are currently being considered for regulation because of potential adverse health effects. In the current study, DCAA and TCAA dermal exposures were investigated in four human subjects during a thirty minute walk or swim in a pool by measuring the pool water concentrations and urinary excretion rates of DCAA and TCAA. These two compounds were eliminated in urine within approximately 3 hours of the exposure, with the dermal DCAA dose being ~6 μg from pool water containing 600 μg/L. The amount of water ingested by each subject during a 30 minute swim was estimated to be between 12 and 45 mL. The DCAA permeability coefficient at pH 7 was calculated to be between 1 and 8 x 10-3 cm/h, when assuming that only 3% of the dermal dose, as was observed for ingestion, was excreted and between 2 and 9 x 10-5 cm/h, assuming that 48% of the dermal dose, an upper limit, was excreted. Exposure estimates indicate that ingestion is the major route of exposure and that the dermal contribution during typical household uses is a minor contributor to the total exposure of these compounds from chlorinated drinking water.