RESUMO
BACKGROUND: Thiodiacetic acid (TDAA) is the main metabolite of vinyl chloride (VC) and 1,2-dichloroethane (EDC) and its urinary level is correlated with the level of exposure to these chemicals. OBJECTIVE: To study dynamics of the excretion of TDAA into urine of polyvinyl chloride (PVC) production workers. METHODS: The study sample consisted of 65 workers of VC and PVC divisions with various time intervals following exposure to the chemicals, 10 shift workers from PVC division, and 34 workers not exposed to the chemicals (control group). Analysis of urinary TDAA was carried out with gas chromatography with mass-selective detector. RESULTS: The concentrations of TDAA in the urine of workers of the VC division and in group of primary occupations who had a high level of exposure to the chemicals, were significantly (p<0.05) higher than that of workers of the PVC production division and group of auxiliary professions. The highest levels of TDAA in the urine of workers were found at the beginning of the next shift and during a long break, 24-48 hours after the cessation of the exposure. CONCLUSION: When conducting biomonitoring studies in PVC production workers, the optimal time for collecting urine samples is at the beginning of the next shift or during a long rest, 24-48 hours after the exposure.