Effects of urinary of organophosphate metabolites on nerve conduction and neurobehavioral performance among farmers in northern Thailand.

Abstract

Farmers are regarded as a high-risk population for pesticide exposure because of the frequency of their occupational exposure to organophosphate (OP) pesticides. The purposes of this study were 1) to compare urinary OP metabolites, nerve conduction, and neurobehavioral (NB) performance between farmers and a control group, as well as between baseline measurement and after spraying OP pesticides; 2) to investigate the factors associated with increased urinary OP metabolites after spraying OP pesticides; and 3) to investigate the effects of OP metabolites on changes in nerve conduction and NB performance after spraying OP pesticides. This study was conducted with a sample size of 71 farmers and a control group of 26. The findings showed that after spraying OP pesticides total dialkylphosphate (DAP) levels were significantly higher than baseline levels. Multiple linear regression showed that increased urinary OP metabolites among farmers after spraying pesticides were negatively associated with wearing a mask when spraying OP pesticides and positively associated with the number of years of farm work and type of sprayer equipment. The results also showed a positive association between the increased urinary total diethylphosphate (DEP) levels and the decreased amplitude of motor nerve conduction. Furthermore, a positive correlation was observed between increased urinary total DEP and decreased right amplitude of sympathetic skin response (SSR). An increase in urinary total DMP was positively associated with a decrease in raw score and a standard score of visual-motor integration (VMI). Our findings provide evidence that exposure to OP pesticides can cause a deficit in nerve conduction and NB performance in farmers. These findings may contribute to the early detection of neurological disease and inform strategies to prevent damage to the peripheral and central nervous systems.