Peripheral nerve dysfunction among workers with long term occupational exposure to pesticides

ABSTRACT

A comparative cross-section study was carried out on 36 workers with long-term exposure to pesticide [pesticide sprayers] and 20 pesticide unexposed controls, from Dekernes, Dakahlia Governorate, Egypt. General medical examination and neurological evaluation were performed to elicit sensory, motor manifestation; as well as neurophysiological study including nerve conduction and electromyography. Plasma cholinesterase level was estimated and correlated to neurological findings. Carbamates and Organophosphates were sprayed by most pesticide sprayers. Most of them had practiced pesticide application with improper personal hygiene, concerning storage, mixing and preparation, spraying, disposal, and after work cleaning up. Symptoms of neuropathy; lower limbs sensory nerve signs; ankle hyporeflexia were insignificantly prevalent among pesticide sprayers while no motor signs were detected among them. A highly significant decrease of the conduction velocity and amplitude of motor unit action potential [MUAP] of the lower limbs examined nerves, and insignificant decrease of their terminal latencies was observed among pesticide sprayers compared to the control. This picture is not evident in the upper limbs examined nerves, in which the conduction velocities are decreased but with no statistical significant difference. This was consistent with axonal neuropathic affection of the examined lower limbs nerves. As regards sensory nerve conduction study there was a highly significant increase of the terminal latency; highly statistical significant decrease of the CV and amplitude of the superficial peroneal nerves and significant decrease of amplitude of upper limbs examined nerves among pesticide sprayers when compared with that of controls. Accordingly peripheral poly neuropathies were found to be more prevalent among pesticide sprayers [38.9%] compared to the control [5.0%]. Of them, 78.6% were subclinical neuropathies and 21.4% were possible neuropathies. Pesticide sprayers had a highly statistically significant lower plasma AChE mean level [1548.9 +/- 801.7 mu/ml] compared to the controls [6751.7 +/- 990.8 mu/ml]. The pesticide sprayers who worked from 15-20 years had the lowest AChE mean level, but the difference was statistically insignificant. Among pesticide sprayers, the means of AChE levels were significantly lower in the workers with neuropathy [981.7 +/- 524.9 mu/ml] more than those without neuropathy [1911.9 +/- 742.5 mu/ml]. Neuropathy was more prominent among sprayers who exposed for long duration [more than 5 years] [11.1 +/- 4.5 years]. Pesticide sprayers are vulnerable to develop peripheral neuropathy 2.78 folds increase when compared to controls. So reduction and legislative control of the pesticide use and disposal seem the best options to protect pesticide sprayers, farmers and the environment from the adverse effects of pesticides. Also the use of protective equipment, the adoption of safety practices during field work, the health education programs about the risks of pesticide exposure, will help a lot to decrease the risk from the exposure to pesticides among pesticide sprayers. Pre-employment measurement of AChE, Occupational health surveillance and periodic medical monitoring with emphasis on the peripheral nervous system are recommended for all pesticide sprayers