JACC Report 43 – sec-Butanol


JACC 043 : sec-Butanol (CAS No. 78-92-2) | March 2004

This report has been produced as part of the Joint Assessment of Commodity Chemicals (JACC) programme. It presents a critical evaluation of the physico-chemical, ecotoxicity and toxicity data of sec-butanol (sBA). Since the last comprehensive review of sBA published by IPCSa in 1987, new data have become available. A hazard/risk assessment will be required under current OECD/EC schemes bc. Almost all sBA, produced world-wide is used for the synthesis of methyl ethyl ketone (MEK). To a lesser extent, sBA is used as a solvent, and in the manufacture of other materials. When released to the environment, sBA partitions entirely into water and air. sBA contributes to the formation of tropospheric ozone, but has a low ozone creation potential. sBA is readily biodegradable and is not expected to accumulate. sBA has a low order of toxicity at all trophic levels. In laboratory animals, sBA is rapidly absorbed and partly excreted as sBA or in conjugated form; the major part is metabolised to MEK. For this reason, the toxicities of sBA and MEK in animals are considered to be closely similar. Accordingly, data from studies conducted with MEK were also reviewed to provide a more complete evaluation of the toxicity of sBA. sBA has a low order of acute toxicity to laboratory animals when administered in single doses, by inhalation or otherwise. sBA is non-irritant to rabbit skin, but is severely irritant to the eye. It is not a skin sensitiser in guinea pigs. The few repeated-dose toxicity studies on sBA are limited. However, studies with MEK suggest that sBA should be of low subchronic toxicity by the inhalation and oral routes of exposure. MEK produced minimal or no systemic effects in laboratory animals following repeated exposures to high doses. sBA is not genotoxic and there is no concern for a carcinogenic potential. sBA showed some foetotoxicity in laboratory animals at high concentrations toxic to the mother, but is devoid of selective developmental toxicity. No adverse systemic effects associated with acute or repeated exposure to sBA have been reported in humans. As sBA is volatile, high exposure levels may result in acute central nervous system effects, including headache and dizziness. sBA, after transformation to MEK, may potentiate neurotoxicity of certain neurotoxic ketones; such effects, however, have not been reported so far in humans.