Delayed Polyneuropathy in Farm Sprayers Due to Chronic Low Dose Pesticide Exposure

BACKGROUND The use of organophosphates (OPs) in developing countries is rising in large quantities and non-secure methods. This problem not only causes acute poisoning but also may lead to chronic diseases such as polyneuropathy. In Iran, 60% of pesticides are organophosphate compounds that may lead to delayed polyneuropathy. OBJECTIVES The purpose of the current study was to evaluate delayed polyneuropathy in farm sprayers due to chronic low dose pesticide exposure. PATIENTS AND METHODS In our cross-sectional study, non-randomized sampling method was performed and 100 farm sprayers (cases) and 100 hospital personnel (controls) after precise systemic and neurological examination were recruited to this study from June 2011 to august 2011. The nerve conduction studies were performed and these indices were recorded: Compound Muscle Action Potential (CMAP), amplitude and Distal Latency (DL) and Nerve Conduction Velocity (NCV) of common peroneal nerve, Peak Latency (PL) and amplitude of Sensory Nerve Action Potential (SNAP) and Nerve Conduction Velocity (NCV) of sural and radial sensory nerves. RESULTS Among 100 cases, 55 farm sprayers complained of non-neurological problems including: ophthalmologic, dermatologic and pulmonary complications. The ophthalmologic complaints (44%) were the most. The mean peroneal CMAP amplitude and NCV, sural PL, radial SNAP amplitude, PL and NCV in the case group were significantly different compared to control group. Mean exposure time to OPs in farm sprayers without neurological problem (40%) was 11.81 ± 5.84 years but in farm sprayers with neurological problems (60%) was 15.70 ± 9.08 years, which represents the effect of OPs exposure duration on neurologic problems. CONCLUSIONS Chronic low dose pesticide exposure could lead to delayed peripheral neuropathy as well as systemic (skin, eyes and lungs) complications. In farm sprayers electrodiagnostic indices were significantly abnormal as compared to control group. The normal indices did not rule out neurologic involvement and it seems that measurement of these indices at the beginning of the farm sprayers employment and intermittently during their work is helpful for detecting delayed polyneuropathy.