In vitro and in vivo percutaneous absorption of 14C-chloroform in humans

Chloroform has been found in potable water and there is concern that significant dermal absorption may arise from daily bathing and other activities. The present study examines percutaneous absorption of 14C-chloroform in vivo using human volunteers and in vitro using fresh, excised human skin in a flow-through diffusion cell system. Fifty microlitre doses of either 1000 micrograms ml-1 chloroform in distilled water, (16.1 micrograms cm-2) or 5000 micrograms ml-1 of chloroform in ethanol, (80.6 micrograms cm-1) were applied to the forearm of volunteers with exhaled air and urine being collected for analysis. Single doses of either 0.4 microgram ml-1 chloroform in distilled water (low dose, 0.62 microgram cm-2, 1.0 ml dosed) or 900 micrograms ml-1 chloroform in distilled water (high dose, 70.3 micrograms cm-2, 50 microliters dosed) were applied to discs of the excised abdominal skin placed in flow-through diffusion cells and perfused with Hepes buffered Hank's balanced salt solution, with a wash at 4 h. In vivo absorption was 7.8 +/- 1.4% (water as vehicle) and 1.6 +/- 0.3% (ethanol as vehicle). Of the dose absorbed in vivo, more than 95% was excreted via the lungs (over 88% of which was CO2), and the maximum pulmonary excretion occurred between 15 min and 2 h after dosing. The percentage of dose absorbed in vitro (skin+perfusate) was 5.6 +/- 2.7% (low dose) and 7.1 +/- 1.4% (high dose). The above data demonstrate that a significant amount of the dissolved chloroform penetrates through the human skin, and that a higher percentage of the applied dose was absorbed using water as vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)