Human Cell Mutagens in Respirable Airborne Particles from the Northeastern United States. 2. Quantification of Mutagens and Other Organic Compounds

Few reports have characterized mutagenic compounds in respirable airborne particles (<2.5 micrometers in diameter; PM_(2.5)) collected at different sites on a regional scale (hundreds of km). Previously, we reported differences in the human (h1A1v2) cell mutagenicity of whole and fractionated organic extracts of PM_(2.5) samples collected in Boston, MA, Rochester, NY, and Quabbin Reservoir, a rural site in western MA. Herein we describe the analysis of mutagens and other organic compounds in these samples. Gas chromatography−mass spectrometry (GC−MS) was used to quantify ∼150 organic compounds, including 31 known human cell mutagens. Molecular weight (MW) 226−302 amu PAHs were the most important mutagens identified:  cyclopenta[cd]pyrene accounted for 1−2% of the measured mutagenicity of the samples, MW 252 PAHs accounted for 4−6%, MW 276−278 PAHs accounted for 2−5%, and MW 302 PAHs accounted for 2−3%. 6H-benzo[cd]pyren-6-one, a PAH ketone, accounted for 3−5% of the mutagenicity. The same compounds accounted for similar portions of the total attributed mutagenicity in each sample. Mutagen levels were similar in the Boston and Rochester samples, and both were significantly higher than the Quabbin sample. This may explain why the mutagenicities of the Boston and Rochester samples were higher than the Quabbin sample. The levels of mutagens found in semipolar fractions, however, could not explain why the mutagenicity of semipolar fractions was 2-fold higher in the Rochester sample than in the Boston sample. Known mutagens accounted for only 16−26% of the total mutagenicity of the unfractionated extracts, and only ∼20% of the mutagenicity of the nonpolar and semipolar fractions. The remaining mutagenicity is likely attributable to other, as-yet unknown, semipolar and polar mutagens, or to interactions among chemical constituents of the samples. These findings are consistent with similar studies performed on airborne particles from Los Angeles and Washington, DC, thus indicating that PAHs, PAH-ketones, and as-yet unidentified polar organic compounds are widely distributed airborne human cell mutagens.