Critical review of the toxicity of methyl n-butyl ketone: risk from occupational exposure.
Methyl n-butyl ketone (MBK) was considered rather harmless until an outbreak of peripheral neuropathy occurred in 1973 among workers exposed to MBK. MBK easily penetrates the skin; pulmonary retention is approximately 80-85% in man. Distribution is widespread with highest levels in blood and liver; MBK also reaches the fetal tissues. MBK metabolism probably depends on the route of exposure, and is very similar to that of n-hexane. The critical organ is the nervous system. These effects find expression as peripheral neuropathy, with potential for serious effects of the central nervous system. From the viewpoint of neurotoxicity, 2,5-hexanedione is the most important metabolite. The neurotoxicity is potentiated by several compounds, while MBK itself potentiates the toxicity of other chemicals. From animal experiments, a no-adverse-effect level (NAEL) could not be established. Peripheral neuropathy may develop in workers exposed to only a few ppm of MBK. The difference in the Occupational Exposure Limits for MBK and n-hexane, as established by several organizations, is questioned in view of the neurotoxic effects of these substances.
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Department of Occupational Toxicology, TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
de Mik
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Bragt
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D000818:Animals; D004347:Drug Interactions; D004784:Environmental Monitoring; D006801:Humans; D008742:Methyl n-Butyl Ketone / Q000009:adverse effects*; D009784:Occupational Diseases / Q000139:chemically induced*; D016273:Occupational Exposure / Q000009:adverse effects*; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced; D012307:Risk Factors
D008742:Methyl n-Butyl Ketone