© 1992 Oxford University Press
research-article |
Dermal Absorption of Dilute Aqueous Chloroform, Trichloroethylene, and Tetrachloroethylene in Hairless Guinea Pigs
Environmental Sciences Division, Lawrence Livermore National Laboratory, University of California Livermore, California 94550
Received April 1, 1991; accepted July 2, 1991
Percutaneous absorption was measured in female hairless guinea pigs dermally exposed for 70 min to very dilute ({small tilde} 10 to 100 ppb) aqueous solutions of 14c-labeled chloroform (CF), trichloroethylene (TCE), or tetrachloroethylene (PCE) in an airtight glass chamber containing no headspace. Similar experiments were conducted using aqueous solutions of TCE at 100,000 ppb. Dermal uptake was estimated by comparing the rate of radiolabel loss from chamber water in systems with and without experimental animals. After each low-concentration dermal-uptake experiment, radiolabel in total urine and feces excreted postexposure was measured and expressed as a fraction of corresponding estimated dermal uptake. For each of the compounds studied, the mean value of these fractions did not differ significantly from that obtained using animals injected with a known dose of that compound, indicating that our experimental system yielded accurate dermal-uptake estimates. The mean permeability coefficients obtained range from 0.13 cm/hr (CF) to 0.37 cm/hr (PCE); those obtained using low- vs high-concentration TCE are not significantly different. The value for CF is very close to one we calculate here from recently published data on CF uptake in human volunteers dermally exposed to aqueous CF while showering with normal tap water. Our results suggest that dermal absorption may be an important route of human exposure to chlorinated volatile organic compounds in domestic water supplies.