Percutaneous absorption of haloacetonitriles and chloral hydrate and simulated human exposures.

Disinfection-by-products (DBPs) have long been a human health concern and many are known carcinogens and teratogens. Skin is exposed to DBPs in water through bathing and swimming; however, dermal uptake of many DBPs has not been characterized. The present studies were initiated to measure the permeation coefficients (K(p) ) for haloacetonitriles (HANs) and chloral hydrate (CH), important cytotoxic DBPs. The K(p) values measured using fully hydrated dermatomed torso skin at 37 °C for the HANs ranged from 0.099 to 0.17 cm h⁻¹, and was 0.0039 cm h⁻¹ for CH. Of the HANs, dibromoacetonitrile had the highest permeability while chloroacetonitrile had the lowest permeability and a direct relationship was observed between their K(p) and their octanol/water partition coefficients (K(ow) ). The K(p) values of the HANs were also approximately 30 times that of CH. The monthly dermal and ingestion doses of HANs and CH of an average American population were estimated using Monte Carlo simulations. The dermal doses of HANs from showering and bathing ranged from 0.39 to 0.78 times their ingestion doses but only approximately 0.02 times their ingestion doses for CH, assuming that the K(p) values determined are applicable to shorter water contact times. However, that ratio can vary markedly with chlorinated swimming pool exposures, with a range of 0.30-2.3 for HANs and 0.19-0.25 for CH. Dermal exposure to HANs and CH seems to be a significant route of exposure and should be considered when evaluating their total exposure during the routine usage of water for bathing and swimming.