Abstract
Purpose : To investigate the function of the peripheral and central nervous system in farmers regularly using organophosphate (OP) compounds either after acute intoxication or following low level repeated exposure. Design : Case control and cross-sectional studies. Materials and Methods : Two groups, each of sixteen farmers regularly involved in dipping sheep, were compared with a group of sixteen healthy controls of similar age range using clinical neurological and neurophysiological assessment. Farmers in group 1 had long-term ill health following episodes of mild to moderate acute OP poisoning while farmers in group 2 had none of the above. Clinical symptoms and signs of neuropathy were recorded. Motor and sensory nerve conduction, electromyography (EMG), quantitative sensory testing and visual, brainstem auditory and somatosensory evoked potentials were measured. Results : A similar pattern of significant abnormalities of distal sensory and motor peripheral nerve axonal dysfunction was found in both farmer groups, but more pronounced in the symptomatic farmers. Conclusions : The findings suggest that long-term peripheral neuropathy can follow acute OP intoxication (group 1). Furthermore, chronic effects may follow repetitive low level exposure to OP compounds (group 2). The profile of dysfunction was similar in the two groups. The parameters measured in the study are useful endpoints in future epidemiological studies.