Human Lymphoblast Mutagens in Urban Airborne Particles

Abstract

While it is known that urban airborne particles typically contain trace levels of bacterial mutagens and rodent carcinogens, little work has been done to identify chemicals in such particles that can genetically alter human cells. In this paper, we describe the analysis of an organic extract of a Washington, DC, airborne particle sample (SRM 1649) for human cell mutagens. Due to the chemical complexity of the extract, a bioassay-directed fractionation method was used to separate mutagenic constituents into chemically simplified fractions. Mutagenicity testing was done using the h1A1v2 cell line, a line of human B-lymphoblastoid cells that have been engineered to overexpress the human cytochrome P4501A1. Chemical analysis of mutagenic fractions was accomplished using GC−MS and HPLC−UV techniques. Our results indicate that ∼20% of the total mutagenicity the extract was accounted for in two fourth-order fractions that contained ∼3% of the total extract mass. These fractions were composed largely of polycyclic aromatic hydrocarbons (PAH). A total of 13 PAH were identified that accounted for ∼15% of the mutagenicity of the extract. Of these, the most important mutagens were cyclopenta[cd]pyrene, benzo[a]pyrene, and benzo[b]fluoranthene, accounting for ∼7, ∼4, and ∼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 previously unknown potent human lymphoblast mutagens, were also identified in the sample. N[2,1-a]P accounted for ∼3% of the extract mutagenicity; N[2,3-a]P, which was present at relatively low levels, accounted for <1% of the extract mutagenicity. The remainder of the mutagenicity was found in fractions that contained more polar compounds. One of 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 oxy-PAH identified, only the ketone 6H-benzo[cd]pyren-6-one (∼0.5%) was found to account for a significant portion of the total mutagenicity of the extract. Nitro-PAH, many of which are potent bacterial mutagens, did not contribute significantly to the mutagenicity of this sample because they were present at low concentrations and because they are not particularly mutagenic in h1A1v2 cells.

Time to Say Goodbye to the 16 EPA PAHs? Toward an Up-to-Date Use of PACs for Environmental Purposes

“…Are they frequently recorded or only rarely, and are they very (site-)specific compounds? Above, the dibenzopyrene isomers were mentioned as highly toxic PAHs that may be relevant for inclusion on any list of environmentally significant PAHs, but up to today no more than some 40 studies report the detection of these compounds in environmental samples: their presence in the environment has been shown in vehicle exhaust (31)(32)(33)(34)(35)(36)(37), air particulate matter (36,(38)(39)(40)(41)(42), house dust (43), coal tar (31,40,44), coal extracts (7), automobile tires (45), particulates from coal combustion (46,47), fly ash (48), sediment and soil (31,40,(49)(50)(51)(52)(53)(54)(55), cigarette smoke (34), and exhaust gases from sewage sludge incineration (56).…”

Photoenhanced NO2 Loss on Simulated Urban Grime

“…[3,4] Sources of PAHs are incomplete combustion of fossil fuels, [12] wood burning, [13] and industrial processes. [14] Some of these PAHs are reported to have carcinogenic and mutagenic properties; [15][16][17] those bearing five or more aromatic rings are predominantly adsorbed onto particulate matter, [18] and therefore their lifetime and fate is strongly influenced by heterogeneous oxidative processes. Recently, Raja and Valsaraj showed that particle-bound naphthalene and phenanthrene are degraded much faster than in the gas phase.…”

Determination of oxygenated polycyclic aromatic compounds in airborne particulate organic matter using gas chromatography-tandem mass spectrometry

“…In the GC-MS chromatogram (Figure 4a), the identification of O-PAHs is difficult due to the presence of many interfering peaks. Retention times allow detection of peaks, which may correspond to phthalic anhydride (3), 9-fluorenone (5) and benzanthrone (10). But the MS mass spectra do not allow confirmation of the identity of these compounds.…”