Variability in biological monitoring of solvent exposure. I. Development of a population physiological model.

Biological indicators of exposure to solvents are often characterised by a high variability that may be due either to fluctuations in exposure or individual differences in the workers. To describe and understand this variability better a physiological model for differing workers under variable industrial environments has been developed. Standard statistical distributions are used to simulate variability in exposure concentration, physical workload, body build, liver function, and renal clearance. For groups of workers exposed daily, the model calculates air monitoring indicators and biological monitoring results (expired air, blood, and urine). The results obtained are discussed and compared with measured data, both physiological (body build, cardiac output, alveolar ventilation) and toxicokinetic for six solvents: 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, benzene, toluene, styrene, and their main metabolites. Possible applications of this population physiological model are presented.