Objective: To modify the method of analysis of urinary diethyl phosphate (DEP) in order to determine the relationship between atmospheric ethion concentration and urinary DEP concentration.

Materials and Method: A cross-sectional study was conducted by collecting atmospheric ethion in the breathing zone of 28 farmers following the NIOSH 5600 method. Urine samples were also collected to analyze urinary DEP concentrations by a modified method using a Gas Chromatography-Flame Photometric Detector (FPD).

Results: The average atmospheric ethion concentration in the breathing zone of farmers was 0.036 + 0.018 mg/m3. The average urinary DEP in pre-shift and post-shift was 0.030 + 0.06 and 0.851 + 1.80 mg/g of creatinine respectively. The average DEP during work shifts was 0.53 + 0.27, and ranged from 0.12 to 1.16 mg/g of creatinine. A high correlation coefficient (r = 0.645) was found between atmospheric ethion concentrations and urinary DEP concentrations at p < 0.001.

Conclusion: The modified method provided a reliable result and the urinary DEP during work shifts was found to be a reliable biomarker of ethion exposure.

Keywords: Ethion, Diethyl phosphate, Organophosphate metabolites