Effects of Methyl N-Butyl Ketone On Behavior and the Nervous System.
Johnson-BL; Setzer-JV; Anger-WK; Lewis-TR
NIOSH 1975:36 pages
The neurologic and behavioral effects of methyl-n-butyl-ketone (591786) (MBK) were studied in monkeys and rats. In the neurologic study, 30 albino-Sprague-Dawley-rats and 24 male Macaca-fascicularis- monkeys were exposed to 0, 100, or 1000 parts per million (ppm) MBK 6 hours a day, 5 days a week. Exposures continued up to 25 weeks for the 1000ppm group, and up to 41 weeks for the 100ppm groups. Once a month, animals were tested for nerve conduction velocity, muscle action potentials (MAP), electroencephalograms (EEGs), and visual evoked potentials (VEPs). In the behavioral study, 12 albino- Sprague-Dawley-rats were trained on a bar press response schedule. Exposures were 0, 100, 1000ppm MBK. Rats were tested following daily MBK exposure. In the neurologic study, monkeys in the high exposure group showed a progressive decrease in the maximum motor conduction velocity (MCV) of the sciatic tibial nerves after 3 months exposure. At 8 months, the MCV for the sciatic tibial nerve in monkeys in the low exposure group was significantly reduced from that of controls. Both monkeys and rats exposed at 1000ppm MBK showed a continuous decrease in MAP amplitude in response to sciatic stimulation. MBK did not affect EEGs. Latencies for average VEPs of the high exposure group increased after 4 months exposure. This effect was not seen in the low exposure group. In the behavioral study, a significant decrease in rate of response was seen in animals exposed to 1000ppm MBK beginning after 2 weeks exposure. No effects on behavior were seen in the lower exposure group. The authors suggest that the performance decrement in the behavior study may be due to a depressant effect of MBK on the central nervous system. MBK produces neurotoxic effects at concentrations as low as 100ppm. Occupational health standards for respiratory exposure to MBK should be set below this concentration.
Animal-studies; Neurotoxicity; Neurotoxins; Exposure-levels; Exposure-limits; Behavioral-testing; Behavioral-tests; Nervous-system-function; Neuromuscular-function;
Division of Biomedical and Behavioral Sciences, NIOSH, Center for Disease Control, U.S. Public Health Service, U.S. Department of Health, Education, and Welfare, 36 pages, 18 references