Differences following skin or inhalation exposure in the absorption and excretion kinetics of trichloroethylene and toluene.

The concentrations of trichloroethylene in breath and blood and the urinary excretion of its metabolites following 30 minutes' direct immersion of one hand in the liquid, were compared with those obtained after four hours' inhalation exposure to the vapour of 100 ppm, described in a previous paper. The comparison shows that the end-tidal air concentrations during the first two hours of the post-exposure period were about twice as high in the case of skin exposure as in that of inhalation exposure, although the uptake of the solvent through the skin was only about one-third of the inhaled uptake. A kinetic approach suggested that differences in trichloroethylene movement in the body would be a principal cause of this discrepancy. The results of a similar series of experiments using toluene suggested that it is less readily taken up than trichloroethylene through the skin. It was concluded from the present investigation that analyses of not only breath but also of blood or urine are necessary and toluene would rarely be absorbed through the skin in toxic quantities during normal industrial use.