Application for the Reassessment of a Hazardous Substance under ...

persistent vertical, mildly erythematous streaks over the posterior andlateral neck; the arms and anterior chest had cleared. Negative patch testresults suggested that the dermatitis resulted from a primary irritant effect ofdichlorvos on the skin. Dermatitis resolved completely approximately 10weeks after onset. The persistence of dermatitis 2 months after exposure isvery unusual, and the author suggested that this may be related to someunique local toxic effect of dichlorvos, but did not speculate further.“In a guinea pig maximization test conducted in this study, induction withdichlorvos by intradermal injection and topical application and subsequentchallenge with topical dichlorvos solutions showed sensitization, thethreshold irritation concentration of dichlorvos on guinea pig skin wasreported to be 1% (Ueda et al., 1994). Cross-reactivity with dichlorvos wasdemonstrated in animals induced with triforine.” (Originals not sighted;ATSDR, 1997)WHO (1988) reported:―In order to study the allergenicity of dichlorvos, the guinea-pig maximizationtest was used. Threshold limit values of primary irritancy tested on the skin ofguinea-pigs (Hartley strain) were 2% or more. In the maximization test, 0.05 and0.5% were used. With 0.5%, 35% of the animals showed slight or discreteerythema. The allergenicity rating as determined by the Kligman test wasmoderate. In combination with methidathion, dichlorvos showed a strongerreaction, indicating cross-sensitization (Fujita, 1985).‖ (Originals not sighted;WHO, 1988)Dichlorvos reassessment – application Page 186 of 436