Environmental and biological monitoring of exposure to toluene, styrene and n-hexane

Eighty-four workers exposed to toluene (printing industry), styrene (fiberglass industries), n-hexane, and other solvents (shoe industry) were monitored with a total of 248 sequential samples. Sampling times varied between a minimum of 2 hours and maximum of 3.5 hours. Highly significant correlations were found between exposure levels to solvents (as daily time-weighted averages) and concentrations of the respective urinary metabolites (hippuric acid, mandelic acid, phenylglyoxylic acid 2,5-hexanedione), confirming that these metabolities are good indices for routine monitoring of subjects occupationally exposed to the above solvents. In view of their results, the authors believe that monitoring individual exposure with personal sequential samples covering the whole workshift can be viewed as the procedure which provides the best information (exact estimate of time-weighted average and evaluation of variable exposures during the workday) for improved understanding of the relations between environmental and biological data, with consequent knowledge of the optimal biological sampling strategy.