HUMAN LYMPHOBLAST MUTAGENS IN URBAN AIRBORNE PARTICLES

While it is known that urban airborne particles typically contain trac e levels of bacterial mutagens and rodent carcinogens, little work has been done to identify chemicals in such particles that can geneticall y alter human cells. In this paper, we describe the analysis of an org anic extra ct of a Washington, DC, airborne particle sample (SRM 1649) for human cell mutagens. Due to the chemical complexity of the extrac t, a bioassay-directed fractionation method was used to separate mutag enic constituents into chemically simplified fractions. Mutagenicity t esting was done using the h1A1v2 cell line, a line of human B-lymphobl astoid cells that have been engineered to overexpress the human cytoch rome P4501A1. Chemical analysis of mutagenic fractions was accomplishe d using GCMS and HPLC-UV techniques. Our results indicate that similar to 20% of the total mutagenicity the extract was accounted for in two fourth-order fractions that contained similar to 3% of the total extr act mass. These fractions were composed largely of polycyclic aromatic hydrocarbons (PAH). A total of 13 PAH were identified that accounted for similar to 15% of the mutagenicity of the extract. Of these, the m ost important mutagens were cyclopenta[cd]pyrene, benzo[a]pyrene, and benzo [b]fluoranthene, accounting for similar to 7, similar to 4, and similar to 2%, respectively, of the extract mutagenicity. Naphtho[2,1- a]pyrene (N[2,1-a]P) and naphtho[2,3-a]pyrene (N[2,3-a]P), two previou sly unknown potent human lymphoblast mutagens,were also identified in the sample. N[2,1-a]P accounted for similar to 3% of the extract mutag enicity; N[2,3-a]P, which was present at relatively low levels, accoun ted for <1% of the extract mutagenicity. The remainder of the mutageni city was found in fractions that contained more polar compounds. One o f these polar fractions contained many different classes of oxygenated polycyclic aromatic compounds (oxy-PAH) including ketones, quinones, coumarins, and carboxylic acid anhydrides; however, of the mutagenic o xy-PAH identified, only the ketone 6H-benzo[cd]pyren-6-one (similar to 0.5%) was found to account for a significant PAH, many of which are p otent bacterial mutagens, did not contribute significantly to the muta genicity of this sample because they were present at low concentration s and because they are not particularly mutagenic in h1A1v2 cells.