JACC Report 41 – n-Butanol

JACC 041 : n-Butanol (CAS No. 71-36-3) | March 2004

This report has been produced as part of the ECETOC Joint Assessment of Commodity Chemicals (JACC) programme. It presents a critical evaluation of the toxicity and ecotoxicity data of n-butanol (nBA). Since the last comprehensive review of nBA by IPCS a in 1987, new data have become available. A hazard/risk assessment will be required under current OECD/EU schemes b,c. nBA is a colourless liquid that is primarily used as an intermediate in the manufacture of other chemicals, and in solvent applications. If nBA is released into the environment (airborne), a major part will be distributed to the water compartment. nBA is rapidly degraded in air and water; little accumulation in soil, biota, sediment or suspended matter is anticipated. nBA has a low order of toxicity at all trophic levels. nBA is readily absorbed through the lungs of humans and laboratory animals and can also penetrate the skin. Following absorption, nBA is rapidly metabolised, ultimately to CO2, with small amounts being eliminated in urine as glucuronide and sulphate conjugates. When administered in single doses to laboratory animals by gavage, inhalation or application to the skin, nBA exhibits a low order of toxicity. Available information on the effects of nBA following repeated exposure is supplemented in this report by data on n-butyl acetate, an ester that hydrolyses to form nBA and acetic acid within minutes of entering systemic circulation. The typical effect of high doses of nBA following single or repeated exposure is a transient, depression (narcosis) of the central nervous system, which is commonly seen with other short chain alkyl alcohols. Specific neurotoxicity is not observed. Specific target organs and selective toxicity have not been identified. nBA is not genotoxic and there is no concern for carcinogenic potential. nBA showed some foetotoxicity in laboratory animals at high concentrations that were toxic to the mother, but is devoid of selective developmental toxicity. Male or female fertility is not adversely affected, as shown by studies with n-butyl acetate. Earlier reports describing neurotoxicity and hearing loss in workers exposed to nBA have not been substantiated. In humans, nBA is slightly to moderately irritant to the skin on prolonged contact, and moderately irritant to the eyes.