Erythema-inducing effects of solvents following epicutaneous administration to man--studied by laser Doppler flowmetry.

Skin exposure to solvents can cause erythema, edema, scaling, and, eventually, irritant contact dermatitis. The irritant potential of chemicals is usually assessed by visual scoring, but in recent years a more objective measuring technique, laser Doppler flowmetry (LDF), has been introduced for the assessment of erythema. The method is noninvasive and allows continuous recording. In the present study 11 solvents were applied for 5 min or less to the volar forearms of a man and the kinetics of the response is shown. For seven solvents (dimethyl sulfoxide, trichloroethylene, n-hexane, carbon tetrachloride, toluene, 1,1,1-trichloroethane, 1,1,2-trichloroethane) an increase was found over the pretreatment values, whereas four solvents (methyl ethyl ketone, ethanol, propylene glycol, distilled water) did not influence blood flow. The findings are discussed in relation to the macroscopic picture (whitening and erythema) and in relation to previous studies of the edema-inducing effects of the same solvents on man and experimental animals. It is concluded that LDF is well worth trying in cases of marginal irritancy and for predictive testing, since it seems to be more sensitive and reliable than the naked eye.