1,1,1-Trichloroethane (methyl chloroform) in urine as biological index of exposure.
Fifteen human volunteers were exposed to 1,1,1-trichloroethane (methyl chloroform) vapor at 72-495 mg/m3 for a period of 2 to 4 hours at rest (ten cases) and during light physical exercise (five cases). Subsequently 60 workers occupationally exposed to 1,1,1-trichloroethane in a refrigerator manufacturing plant were studied (median value: 178 mg/m3; geometrical standard deviation: 2.19 mg/m3). As expected, the relative uptake (R) of 1,1,1-trichloroethane decreased in the course of exposure at rest (R = 0.44 after 20 minutes of exposure; R = 0.26 after 240 minutes of exposure). Both in the experimentally exposed subjects and in the occupationally exposed workers, the urinary concentration of 1,1,1-trichloroethane showed a linear relationship to the corresponding environmental time-weighted average concentration. The correlation coefficients (r) were 0.95 in occupationally exposed subjects and more than 0.90 in experimentally exposed groups. A linear equation also existed between urinary concentration and amount of 1,1,1-trichloroethane absorbed (r = 0.88). The findings indicate that the urinary concentration of 1,1,1-trichloroethane can be used as an appropriate biological exposure indicator. In occupationally exposed subjects performing moderate work, the urinary 1,1,1-trichloroethane concentration corresponding to the time-weighted average of the threshold limit value was found to be 860 micrograms/L and its 95% lower confidence limit (biological threshold) 805 micrograms/L.
Imbriani
M
M
Department of Preventive, Occupational and Community Medicine, University of Pavia, Italy.
Ghittori
S
S
Pezzagno
G
G
Huang
J
J
Capodaglio
E
E
D000328:Adult; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000652:urine*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D005082:Physical Exertion; D012997:Solvents / Q000652:urine*; D014240:Trichloroethanes / Q000652:urine*
D006843:Hydrocarbons, Chlorinated; D012997:Solvents; D014240:Trichloroethanes; C024566:1,1,1-trichloroethane