Proposed biological threshold limit values for industrial exposure to trichloroethylene vapor.

A model was used for the simulation of the pharmacokinetics of inhaled trichloroethylene (TRI) vapor. Computed data of TRI in alveolar air and of trichloroacetic acid (TCA) and trichloroethanol (TCE) in blood and urine agreed satisfactorily with experimental results obtained by various authors. Biological threshold limit values were calculated for subjects exposed at rest to a steady concentration of 100 ppm of TRI in ambient air, between 0800 and 1200 and between 1300 and 1700, five days week during the whole year. The Monday to Friday range of values for urinary excretion (243--322 mg of TCA/24 h and 288--429 mg of TCE/24 h) roughly corresponded to the findings of several surveys among TRI workers in industry. The hypnotic effect of TCE and/or TRI during steady or fluctuating industrial TRI exposure was discussed with the aid of the model.