Evaluation of EMG examination as an indicator of worker susceptibility to organophosphates exposure

A study of crop spray workers, both ground and air crews, was conducted in two consecutive spraying seasons. The study was aimed at evaluating the effectiveness of EMG parameters in validating the effects of exposure to organophosphate (OP) compounds for workers reporting mild clinical symptoms. It was also designed to examine whether these parameters could identify individuals who were more susceptible than others to OP absorption, and who were likely to exhibit symptoms at low levels of exposure. EMG examination included sensory and motor latency and conduction velocity determinations in upper and lower limbs. EMG levels were determined at the start and after the end of the first season and in the midst of the second season. Results show that EMG parameters correlated with symptoms prevalent during the spraying season. This correlation was already present at the start of the season when absorption was low. Several EMG parameters (e.g. MCV Ulnar N. above elbow) recorded at the beginning of the first season were associated with symptoms manifested both in the first and the second seasons. Thus, EMG measurement appears to identify workers who are susceptible to OP absorption and will exhibit symptoms when actually exposed. It was therefore concluded that EMG changes detected at the start of the spraying season could serve as efficient indicators of worker susceptibility to exposure to OP compounds and thus subsequent preventive measures could be taken.