The pathology of allyl chloride neurotoxicity in mice

Allyl chloride is known to produce a neuropathy in man after occupational exposure to its vapour. The present study describes the neuropathy which develops in mice given allyl chloride by mouth. Mice were dosed three times weekly with 300 or 500 mg/kg allyl chloride for periods from 2-17 weeks. Functional disability was observed in some animals. Apart from evidence of focal kidney damage in 70% of dosed mice, pathological changes were restricted to the nervous system. Nerve fibre degeneration was found in many peripheral nerves and in roots, tending to be more marked distally and to affect more motor than sensory nerves. Degenerated fibres were also found in dorsal, ventral and lateral columns of the spinal cord. Males were more severely affected than females. Increased numbers of filaments were on early axonal change, occurring multifocally and apparently preceding axonal degeneration. No neuronal death was observed, but occasional anterior horn and dorsal root ganglion cells showed some morphological changes. Vacuolated lesions mainly due to swelling of astrocytes and their processes were found in the ventral horn in cervical and lumbar regions of spinal cord. Animals appeared to become tolerant to allyl chloride after continuous dosing. This neuropathy appears to be a central-peripheral distal type of axonopathy.