Urinary Ethylenethiourea as a Biomarker of Exposure to Ethylenebisdithiocarbamates

A method for the determination or urinary ethylenethiourea (ETU), a major metabolite of ethylenebisdithiocarbamates (EBDTCs), is described. ETU is extracted from human urine, in the presence of ethylenethiourea-d₄ as the internal standard, using dichloromethane. The residue is reacted to form the bis -(tert -butyldimethyilsilyl) derivative and analyzed using gas chromatography-mass spectrometry (GC-MS) in the electron impact/single-ion monitoring (EI/SIM) mode. The linearity and precision of the assay are good over the entire investigated range (0–200 �g/L). The detection limit of the assay after correction for urinary creatinine is 0.5 �g/g creatinine. A protocol for biological monitoring through determination of urinary ETU is provided. The protocol was applied to study 47 agricultural workers exposed to EBDTCs in the vineyards and 33 controls. In workers postexposure samples, median level of urinary ETU was 8.8 (from less than 0.5 to 126.3) �g/g creatinine. This level is significantly higher than those found in worker preexposure samples and in controls, used as reference values.