Trichloroethylene exposure. Biological monitoring by breath and urine analyses.

A mathematical model developed previously has been used to study some aspects of biological monitoring of exposure to trichloroethylene (TRI) by the analysis of this solvent in alveolar air or of its metabolites, trichloroethanol (TCE) and trichloroacetic acid (TCA), in urine. Assuming that a biological control must be representative of the time-weighted average concentration (TWA), it was found that sampling for TRI and TCE analyses must be carried out the morning after the exposure being considered. On the other hand, for a TCA analysis, the timing of urine sampling is not a determinant factor. Theortical limit concentrations have been set up for these biological indicators, but it is shown that their application must be restricted to exposures which are quantitatively reproducible from one day to the next. In all other cases, it appears that this monitoring method can lead to errors in the estimated exposure concentrations. A tentative method of biological monitoring is therefore proposed. It is based on the analysis of TCE in the urine or TRI in the alveolar air before and after the exposure being monitored. TCA is not considered to be sensitive enough to variations in the inspired concentration to be used as an indicator of a single exposure risk.