Butanone oxime [MAK Value Documentation, 2013]

Abstract

Supplement 1997 MAK value/classification see Section III, Category 2ofthe List of MAK and BAT Values Date of evaluation 1997 CAS number 96-29-7Since publication of the documentation from 1979 documentation "Butanonoxim" 1979 (German), further studies have yielded results which make it necessary to reevaluate the substance. 1T oxic Effects and Mode of ActionButanone oxime is taken up orally, dermally and by inhalation. The substance has strong local irritative effects on the mucous membranes. After long-term exposure of rats and mice, damage to the olfactory epithelium was observed even at the lowest concentration tested of 15 ml/m 3 . Methaemoglobin was produced after short-term exposure to concentrations of 400 ml/m 3 and above; concentrations of around 700 ml/m 3 and above led to sedative and narcotic effects with hypoactivity after aphase of agitation. After repeated exposure for up to ay ear, methaemoglobin was formed even at concentrations of 100 ml/m 3 ,w hile adaptation was observed after long-term exposure. Enlargement and pigmentation of the spleen, and extramedullary haematopoiesis in the liver are connected with the erythrocyte-damaging effects of butanone oxime.After long-term inhalation, the most important effects are the hepatotoxic effects in addition to the damage to the olfactory epithelium. In male rats and mice, toxic effects on the liver were observed after concentrations of 15 ml/m 3 as well as the local effects. After concentrations of 75 ml/m 3 and above, the incidence of liver adenomas in male rats was increased, and butanone oxime concentrations of 375 ml/m 3 led to asignificant increase in the incidence of liver carcinomas in the male animals. The occurrence of DNA and RNA modifications in the liver of rats exposed to butanone oxime indicates al iver-specific activation of butanone oxime to produce metabolites with genotoxic potential.In in vitro genotoxicity studies, except for one positive mouse lymphoma test without metabolic activation, mostly negative results were obtained (Salmonella mutagenicity test, and tests for sister chromatid exchange (SCE), unscheduled