Electrophysiological findings in diphenyl poisoning

Abstract

The fungistatic agent diphenyl caused fatal poisoning with signs of neurotoxicity in a worker in a Finnish paper mill. This initiated a neurophysiological study of 24 workers occupationally exposed to diphenyl. 10 men showed EEG abnormalities, mainly diffuse or generalized ones. The abnormalities persisted on reexamination 1 and 2 yr later. 9 subjects had EMG abnormalities; 7 also exhibited fibrillations in some muscles. 1 subject showed a long rhythmic series of fasciculations similar to the spontaneous activity described in infantile spinal muscular atrophy. Nerve conduction velocity, especially that of slower motor fibers, was reduced in several cases. Electroneuromyographic abnormalities also persisted on reexamination. Although diphenyl is considered a comparatively safe chemical, it showed evidence of neurotoxicity when workers were exposed to concentrations in excess of the presently accepted threshold limits. Electrophysiological methods should be applied for the early detection of occupational hazards.