EVALUATION OF BIOLOGICAL MONITORING PARAMETERS FOR OCCUPATIONAL EXPOSURE TO TOLUENE

A survey was conducted in a rotogravure printing plant with inhalatory and percutaneous exposure to toluene. Workers (n=9) were followed for 2 consecutive days and the frequency and duration of skin contact wit h toluene were monitored. In order to assess percutaneous absorption a n airstream helmet was worn during one day. Urine and exhaled air samp les were collected simultaneously 5 times each day for toluene (urine and breath) and hippuric acid (urine). The mean (personal air sampling ) exposure concentration was between 30 mg/m3 and 600 mg/m3. The best biological monitoring parameter of external exposure (without a helmet ) was the concentration toluene in exhaled air 8 h after work (r=0.99) . While wearing the airstream helmet the relationship between external exposure (measured in the helmet) and concentrations in exhaled air a nd urine deviated from the preceding relations. This was likely the re sult of the high body burden and not of skin contact with toluene. Ski n contact with toluene (usually by cleaning of the hands) was limited to 0-30 minutes a day, with an average of about 5 minutes. During expe rimental exposure (n=6) in which the hands were washed with toluene fo r 5 minutes the toluene in exhaled air (max after 1040 min) clearly de monstrated skin absorption of toluene. The next morning 0.1 mg/m3 tolu ene was still detectable; this was less than the concentration measure d the next morning in exhaled air of workers: between 0.5 and 10 mg/m3 .