Neurophysiological investigations and determinations of cholinesterase activity on plasma and erythrocytes were carried out on 11 Swedish spraymen exposed to bromophos, diazinon, dursbane, and malathion. Plasma cholinesterase activity was significantly reduced after work, while erythrocyte cholinesterase activity was unchanged. In none of the workers with a decreased plasma cholinesterase activity after work could any related acute neuromuscular disturbance be detected when the men were tested with repetitive nerve stimulation and with single fiber electromyography. Signs of subclinical neuropathy were present as a slight reduction in sensory conduction velocity and increased fiber density in some workers.

Key terms cholinesterase activity; electromyography; neuromuscular function; neuromuscular transmission; neuropathy; occupational exposure; organophosphorus compound; organophosphorus insecticide; pesticide; single fiber elecgtromyography