Skin irritancy from propylene glycol.

Two sensitive methods for the assessment of skin irritancy reactions to propylene glycol (PG) have been used: laser Doppler flowmetry in man for erythema and skin fold thickness measurements in man, guinea pigs and rabbits for edema. Single (open and occlusive) and repeated (open) exposures were used. Trafuril was used as positive control for the flowmetric studies. In man an increased blood flow was recorded only when PG was applied under occlusion. A statistically significant increase in skin fold thickness was observed from day 7 in the guinea pig, but not in man (daily exposures for 36 days). It is concluded that occlusion seems to be a crucial factor and that skin fold thickness measurements in guinea pigs and rabbits is a useful, complementary method for the detection and prediction of marginal irritants.