Biological monitoring of occupational exposure to tetrachloroethene.

Abstract

In the breathing zone of 32 workers concentrations of tetrachloroethene were measured during 5 consecutive workdays. The feasibility of biological monitoring was tested by the measurement of the concentrations of tetrachloroethene in blood and exhaled air and the urinary excretion of trichloroacetate acid and trichloroethanol. The best parameter to estimate the time-weighted average [TWA] exposure to tetrachloroethene over the whole workweek was the concentration of tetrachloroethene and trichloroacetic acid in blood 15-30 min after the end of the workday at the end of the workweek. Among the noninvasive methods the best parameter was the tetrachloroethene concentration in exhaled air 15-30 min after work at the end of the workweek, followed by the measurement of trichloroacetic acid in urine at the end of the workweek. In exposure to 2050 .mu.mol tetrachloroethene/m3 (340 mg/m3, 50 ppm) the estimated values for the biological parameters were 13.2 .mu.mol tetrachloroethene/l blood, 33 .mu.mol trichloroacetic acid/l blood, 920 .mu.mol tetrachloroethene/m3 exhaled air and 6.1 .mu.mol trichloroacetic acid/mmol creatinine in urine, respectively. With 95% confidence it may be stated that an individual with a value for a biological parameter not exceeding 8.3 .mu.mol tetrachloroethene/l blood, 20 .mu.mol trichloroacetic acid/l blood, 515 .mu.mol tetrachloroethene/m3 exhaled air and 3.0 .mu.mol trichloroacetic acid/mmol creatinine, respectively, had an exposure not exceeding 2050 .mu.mol tetrachloroethene/m3. The measurement of trichloroethanol in urine may be used for the estimation of the TWA exposure over the previous 2 days. The concentration of tetrachloroethene in exhaled air 15-30 min after exposure had little value for the estimation of the TWA exposure over the last 4 h. On Monday morning the concentration of tetrachloroethene ine xhaled air was still .apprx. 15% of the TWA exposure concentration during the whole preceding workweek. The half-time of trichloroacetic acid in urine and blood during the weekend was .apprx. 65-90 h.