Toxicity of hydroxylamine sulfate following dermal exposure: variability with exposure method and species

The acute toxicity of hydroxylamine sulfate (HS) and phenylhydrazine hydrochloride (PHZ) were compared in the rabbit and rat following a single 24-hr dermal exposure. The test materials were applied topically and occluded under a plastic or gauze cover or were injected sc. Distilled water served as a control. HS and PHZ produced similar hematotoxic effects consisting of methemoglobin formation, anemia, and reticulocytosis. HS and PHZ proved to be more toxic to the rabbit than to the rat although both chemicals produced similar hematological effects at equivalent dose levels within the same species. HS proved strikingly more toxic when administered under plastic than under gauze despite the fact that both methods included occlusion. PHZ toxicity was less variable with exposure method. HS and PHZ were lethal to the rabbit but no deaths occurred in the rat. The results of this study indicate that HS and PHZ show similar hematotoxicity and, therefore, the clinical data available on PHZ may be useful in predicting the hematological effects of HS on humans.