|
1000
|
Abstract/Summary
|
-
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the biological tolerance value at the work place (BAT value) for trimethylbenzene, considering dimethylbenzoic acids in urine to characterize the internal exposure. The BAT value for trimethylbenzene from 2007 was established based on the 95th percentiles. After redefinition of the BAT value as correlate for the mean value from several investigations in one worker, a reevaluation of the BAT value has become necessary. Inhalation chamber studies by Kostrzewski et al. (1997) and Knecht et al. (2000, 2003) provide mean values for dimethylbenzoic acid (DMBA) excretion. With a trimethylbenzene concentration at the MAK value level of 100 mg/m3 (20 ml/m3), Kostrzewski et al. (1997) found a mean sum concentration of the DMBA metabolites of 450 mg/g creatinine, and Knecht et al. (2000) of 417 mg/g creatinine. With a trimethylbenzene concentration of 90 mg/m3 (18 ml/m3), 269 mg DMBA metabolites/g creatinine were determined (Knecht et al. 2003). Based on these studies by Kostrzewski et al. (1997) and Knecht et al. (2000, 2003) the sum concentration (mean value) of the DMBA metabolites of 400 mg dimethylbenzoic acids (sum of all isomers after hydrolysis)/g creatinine is established as BAT value. Samples should be taken at the end of exposure or the end of the shift, and after several shifts for long‐term exposures, because Jones et al. (2006) described cumulative effects after repeated exposure, whereas this phenomenon was not observed by Knecht et al. (2000).
|
