Syncarcinogenic action of polycyclic hydrocarbons in automobile exhaust gas condensates.

The carcinogenic action of the hydrocarbon mixture predominantly found in condensates of automobile exhaust gas can be attributed almost exclusively, on the basis of the results presented here, to a group of substances (PAH) with an insignificant weight proportion. It was not possible to demonstrate an inhibitory action of most of the weak-to-inactive hydrocarbons; on the contrary, an additive effect of the two types could be observed. At very high doses (almost 10 times higher than the highest doses selected in the rest of the trial) the group of substances which were supposed to be non-carcinogenic also proved to be biologically effective. Subsequent individual studies on the same animal strain should clarify whether this action is to be attributed to one or two representatives of this group, e.g., benzo[e]pyrene or chrysene.