[Experimental ethylene oxide neuropathy. Chronic exposure to 250 ppm in rats]

In Wistar rats subjected to a six-hour exposure to ethylene oxide (ETO) at the concentration of 250 parts per million once a day, five times a week for 9 months, histopathologic studies of myelinated fibers of the proximal sural, distal sural and peroneal nerves and of the fasciculus gracilis at the fifth thoracic and third cervical segments of the spinal cord were performed to reveal whether ETO of such concentration produces the degeneration of the primary sensory neuron. Throughout the study, no definite abnormality of the gait or posture was observed in both control and test rats. Qualitative histologic studies disclosed preferential distal axonal degeneration of myelinated fibers in both sural nerves and gracile fascicles in test rats, although the extent of the distribution and the severity of the degenerative findings were variable among test rats. Therefore, it was concluded that exposure to 250 ppm ethylene oxide produces central-peripheral distal axonal degeneration of the primary sensory neuron in rats.