[Mutagenicity of mixtures of halogenated aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in the Ames test with TA98 and TA100]. 
Within the framework of the assessment of the genotoxic potential of environment samples the Salmonella-microsome-test (Ames-test) is often used as a screening-test.  It is one of the most applied biotest systems and possesses a large scientific acceptance.  Because most environment samples are mixtures of various substances, possible effects resulting from the combination should be taken into account with regard to the mutagenic potential.  In this context we investigated eight polycyclic aromatic hydrocarbons each combined with six halogenated aliphatic hydrocarbons as to their mutagenicity in the Salmonella-microsome-test with TA98 and TA100.  For an exogenous metabolizing system, Arochlor 1254 induced rat liver S9-mix was used.  Benz-a-pyrene in combination with bromodichloromethane (Ames neg.  in TA98 and TA100 +S9) showed an increase in the number of the revertants up to 25% in TA98 and TA100 (+S9).  Carbon tetrachloride (Ames neg.  in TA98 and TA100 +S9) showed in TA100 (+S9) an increase in the number of the revertants of 18% at most.  In the combination 3-methylcholanthrene with dichloromethane the number of revertants in TA98 (+S9) increased by 25% and in TA100 (+S9) by 18%.  Hexachloroethane (weakly mutagenic in TA98 +S9) in combination showed in TA98 (+S9) a slightly increased number of revertants with benz-a-pyrene as well with 3-methylcholanthrene.  All the other substances tested (chrysene, phenanthrene, anthanthrene, dibenz-a, i-pyrene, triphenylene, fluoranthene) in combination with either tetrachloroethylene or trichloroethene did not cause an increase in mutagenicity.