DOSE-DEPENDENT METABOLIC INTERACTION BETWEEN BENZENE AND TOLUENE INVIVO AND INVITRO

When benzene or toluene was administered to rats ip in combination with the other, their disappearance rate from blood and the rate of urinary excretion of their metabolites were delayed compared with those when they were given separately. This metabolic interaction was found to be dose dependent. The metabolism of benzene or toluene studied in vitro with rat liver 10,000g supernatant fraction was inhibited competitively by the presence of the other. The solubility of benzene and toluene in blood and their binding with bovine serum albumin were not influenced by the presence of the other, indicating that absorption and distribution are unaffected by their simultaneous presence. A human experimental exposure to a mixture of benzene and toluene revealed that there is no significant interaction between them with respect to their fate when exposure is near the threshold limit value. © 1979.