[Ames test study of the effect of 2nd-phase biotransformation reactions on the level of mutagenic action of a number of chemical compounds].

Introduction of cosubstrates for reactions of conjugation with the reduced glutathione, glucuronic acid and sulphate is shown to modify (increase or decrease) the level of mutagenic effect of thiophosphamide, nitrosomethylurea and DDDTDP on S. typhimurium TA 1950 or TA 1534.