Urinary organophosphate concentration of agricultural workers in Thailand

Abstract

               Pesticides can help eliminate various pests but it has an impact on the environment and human health. The purpose of this study was to assess exposure to organophosphate pesticides from 216 agricultural workers (51 rice farmers, 37 vegetable farmers, 70 rice and sugarcane farmers, and 38 rice and vegetable farmers) in Nakorn Sawan and Phitsanulok province, using questionnaires to collect information and measure the concentration of organophosphate (OP) metabolite in urine by gas chromatography-mass spectrometry (GC-MS). The results showed that detection limit (LODs) for the method was in the range of 4.46-6.73 ng/mL. The percentage of recovery of each Dialkylphosphate (DAP) analysis method at concentrations from 2.5 to 50 ng/mL were in the range of 94.29-105.01%. All groups of agricultural workers had at least one DAP metabolite presented in their urines. The detection frequencies of DAPs were in the range of 0-94.3%.  The median of total dialkyl phosphate (∑DAPs) was the highest among the vegetable farmers. The top 3 symptoms developed after spraying pesticides were sweating, dizziness, and headache, respectively, and an association between ∑DAPs and blurred vision symptoms (p = 0.011) was found. The high urinary DAP concentrations in this study are found; therefore, the extensive training of knowledge and understanding about proper use of personal protective equipment and toxicity of organophosphate pesticides is necessary for monitoring and surveillance of farmers.