Neurophysiological and neuropathological evaluation of primates exposed to ethylene oxide and propylene oxide.
Setzer-JV; Brightwell-WS; Russo-JM; Johnson-BL; Lynch-DW; Madden-G; Burg-JR; Sprinz-H
Toxicol Ind Health 1996 Sep; 12(5):667-682
The neurophysiological and neuropathological effects of ethylene- oxide (75218) and propylene-oxide (75569) were evaluated in exposed primates. Groups of 12 adult, male cynomolgus-monkeys were exposed to either ethylene-oxide at concentrations of 50 or 100 parts per million (ppm) or propylene-oxide at 100 or 300ppm. Control monkeys were sham exposed. Exposures were for 7 hours/day, 5 days/week for 24 months. Six assessments of body weights, electroencephalograms, and motor nerve conduction velocities of the sciatic and ulnar nerves were made throughout the exposure period. Although the monkeys exposed to 100ppm ethylene-oxide had significantly lower mean weights, significant differences in nerve conduction velocities were not evident among the groups. Ten animals (two from each exposure group) were sacrificed for neuropathological examinations after termination of exposures. Multiple axonal bodies were found in the nucleus gracilis in seven of eight oxide exposed animals, demyelination was found in two monkeys exposed to ethylene-oxide, and a single axonal body was found in one of the two control monkeys. The authors believe the lack of a dose response relationship suggests the effect may not be related to oxide exposure. In a follow up study, no treatment related effects were detected when nerve conduction velocity and neuropathology were assessed in the remaining monkeys 7 years after exposure terminated. The authors conclude that under the conditions of this study, no significant neurophysiological effects were found in nonhuman primates following chronic exposures to ethylene-oxide and propylene- oxide.
NIOSH-Author; In-vivo-study; Inhalation-studies; Fumigants; Epoxides; Growth-inhibition; Neurophysiological-effects; Neurotoxicity; Neuropathology; Nerve-function; Body-weight; Chronic-exposure; Electroencephalography
Dennis W. Lynch, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, C23, Cincinnati, OH 45226
Toxicology and Industrial Health