Contribution of primary aromatic amines to the mutagenicity of gasifier tars and coal oils.

Two reactions that chemically alter primary aromatic amines (PAA) were used to assess the contribution of these compounds to the indirect bacterial mutagenicity of tar from an experimental low Btu gasifier. The first reaction, nitrosation, effectively eliminated the mutagenicity of several PAA standards and a coal oil when run in a low pH media (1.2). When applied to gasifier tar, extensive direct (not requiring metabolic activity) mutagenicity was generated. This direct mutagenicity limited the interpretation of results. When the pH of the reaction media was raised to 2.5, the mutagenicity of PAA standards and the coal oil were still greater than 90% eliminated, however, no direct mutagenicity was observed for the gasifier tar. Furthermore, only 61% of the indirect (requiring metabolic activation) mutagenicity was eliminated. Acetylation reduced the indirect activity of most primary amine standards by greater than 79%. Acetylation of the tar likewise eliminated part, but not all, of the activity, whereas most of the activity of the coal oil was eliminated. These results indicated that a much lower percentage of the mutagenic activity of low Btu coal tar samples was due to primary aromatic amines than was the case for coal oil.