Owing to the abrasion of tar-containing or bituminous road surfaces particles are liberated which contain carcinophilic poly-aromatic hydrocarbons e.g. 3.4-benzpyrenes (BP). The effects of abrasion were determined by comparative measurements alongside a highway section of tar asphalt and one of concrete, both subjected to an identical traffic load. Airborne dust, sedimented dust near the ground and the degree of sewage pollution were measured. The wearing layer of the tar-asphalt surface consisted of TA16: max. grain size 16 mm; bonding agent TB 2000(containing 13 per cent tar pitch and 87 per cent bitumen). With a mean traffic load of 9000 vehicles per day abrasion liberated 15 mg 3.4-benzpyrene per month in winter and in summer 10 mg 3.4-benzpyrene per month and per 1 meter length of a two-laned highway. It was found that in the coarser dust particles the abrasion material containing 3.4-benzpyrene prevails. As a result, the tar asphalt abrasion in precipitated dust contained more than 50 per cent of total benzpyrene, while its share amounted even to 70 per cent of the total load in the floating fraction of waste water.