TOWARDS A BIOLOGICAL MONITORING STRATEGY FOR TOLUENE

Three biological monitoring methods for assessing toluene uptake/exposure have been evaluated in a field study over a 4-yr period. Breath analysis using mass spectrometry is rapid, non-invasive and capable of monitoring both pre- and post-shift alveolar air concentrations of toluene. Breath toluene concentrations of about 600 nmole 1. ** minus **1 in samples taken 10-20 min post-exposure and 60 nmole 1. ** minus **1 collected 16 h post-exposure correspond to an exposure of 100 ppm toluene for 8 h. Blood toluene analysis is relatively simple and is suitable for biological monitoring. A blood toluene concentration of about 20 mu mole 1. ** minus **1 in a sample taken at the end-of-shift corresponds to an exposure of 100 ppm toluene with an upper 95% confidence limit of 55 mu mole 1. ** minus **1. Urinary hippuric acid was found to be an unreliable method of monitoring workers, particularly at low exposure concentrations. Until simple, reliable breath monitoring devices are available we suggest that biological monitoring for toluene should be based on blood toluene measurements collected at the end of shift and that a biological exposure limit might assist in reducing exposure.