Primary irritant contact dermatitis from synthetic pyrethroid insecticide exposure

Synthetic pyrethroids are widely used insecticides with numerous applications, varying from food protection to general pest control. Humans are capable of tolerating greater acute and chronic exposures to the pyrethroids than to many other insecticides. An abnormal cutaneous sensation (paresthesia) is known to occur after dermal contact with the pyrethroids. Recent field studies have indicated that a primary irritant contact dermatitis may also develop. This investigation evaluated dermal irritancy from cutaneous synthetic pyrethroid application to albino rabbits. Through repeated daily applications of either fenvalerate or permethrin, a slight erythema was noted visually which correlated with increased cutaneous blood flow measured by laser Doppler velocimetry. Histopathological changes were also documented, but no significant differences were detected in edema or thermal variation.