Thanks for the corrections OC pro - rereading my post, it does appear that I overstated the case.
The distinction I intended to make was that most of the toluene that enters the body is readily oxidized by the CYP450 enzymes in the liver to form innocuous glucoronides that are rapidly excreted. The body can efficiently clear toluene from its system. This metabolic pathway is not available to benzene. Instead, any benzene that is metabolized goes through a much slower pathway involving direct oxidation of the benzene ring, leading, as OC pro pointed out, to highly reactive oxygenated species that are not excreted and are particularly adept at causing DNA damage. The body will slowly clear the benzene out, but it is removed unchanged, and the longer it is present, the more likely it is to undergo this alternative metabolic pathway and cause damage.
Toluene, due to the stabilizing effect of the methyl group, would be expected to undergo this second metabolic pathway even better than benzene, except that it is so rapidly cleared by the first metabolic pathway.