Mutagenicity of bitumen and asphalt fumes.
The mutagenicity of asphalt fumes was tested with the Salmonella bioassays. The aim was to investigate if recycled additives modify the genotoxicity of emissions. Recycling of old asphalt is increasing, and we studied also the mutagenicity of emissions sampled during the re-use of asphalt. The composition of vapours and fumes were analysed by gas chromatography and by liquid chromatography. Bitumens containing coal fly ash (CFA) or waste plastics were heated to the paving temperatures in the laboratory. In the field, bitumen fumes were collected during paving of stone mastic asphalts (lime or CFA as a filler), remixing of stone mastic asphalt (lime or CFA as a filler), and of asphalt concrete. All the lab-generated vapour fractions were non-mutagenic. The particulate fractions were mutagenic with TA98 in the presence of the S9 activation. In addition, the lab-fumes from bitumen containing waste plastics were positive with both strains without S9. Only particulate fractions sampled in the field were tested. They were mutagenic with and without metabolic activation with both strains. The mutagenic potency of the field samples was higher than that of the lab-generated fumes without S9, and the remixing fumes were more mutagenic than the normal paving and lab-generated fumes with S9. The use of inorganic additive, CFA, did not change the mutagenicity of the fumes, whereas the organic additive, waste plastics, increased the mutagenicity of the laboratory emissions significantly.