Conjugated serum bile acid concentrations in workers exposed to low doses of toluene and xylene

Recent studies of non-halogenated cyclic carbon solvents have shown little evidence of hepatotoxicity, although these negative findings might be explained as a consequence of the incapacity of the existing screening procedures to detect liver changes at an early stage. In fact, the uncertainties regarding the evaluation of liver function have been underlined and the need for simple, non-invasive tests of liver function has been emphasised. Recently, a relatively new test of hepatic function, the measurement of serum bile acids, has been studied in workers occupationally exposed to a variety of chemicals (styrene, vinyl chloride, and solvent mixture). During exposure to toluene and xylene at concentrations below the current TLV-ACGIH, we have studied the behaviour of serum bile acids in relation to environmental concentrations of toluene and xylene and to indices of internal dose (toluene and xylene in blood and urine) to evaluate the existence of the relation between exposure and effect.