William P. Harger

Mutagens in diesel exhaust particulate identification and direct activities of 6-nitrobenzo[a]pyrene, 9-nitroanthracene, 1-nitropyrene and 5H-phenanthro[4,5-bcd]pyran-5-one

Organic extracts of ambient particulate matter are directly mutagenic in the Ames Salmonella assay (Pitts et al., 1975, 1977a, b; Talcott and Wei, 1977; Tokiwa et al., 1977; Chrisp and Fisher, 1980; Hoffmann et al., 1980) with the activity concentrated in particles < 1 #m in diameter (i.e., in the respirable size range) (Pitts et al., 1978a, b; Pitts, 1979; Talcott and Harger, 1980). Thus the rapidly increasing use of diesel engines in light-duty motor vehicles is of concern (NAS, 1980) because they emit high levels of respirable particulate organic matter (POM) which will significantly increase the existing atmospheric burden of POM. As with ambient particles, organic extracts of this diesel POM not only contain carcinogenic and promutagenic PAH such as benzo[a]pyrene (BP) (NAS, 1972), but also chemicals which are strong, direct** mutagens in the Ames test (Huisingh et al., 1978; NAS, 1980; Pepelko et al., 1980). Currently, this direct activity cannot be explained by the presence of any known carcinogens and attention is being focussed on nitroarenes as possible major contributors (NAS, 1980; Rosenkranz et al., 1981; Mermelstein et al., 1981). Certain members of this chemical class (e.g., l-nitropyrene) are strong, direct mutagens and have been found (or tentatively identified) in POM from ambient air (J~iger, 1978; Wang et al., 1980), simulated atmospheres (Pitts et al., 1978, b; Pitts, 1979), carbon black used in toners (LOfroth et al., 1980; Rosenkranz et al., 1980) and typewriter ribbons (Alfheim et al., 1981), and diesel exhaust particulate (Pederson and Siak,

The contribution of nitro- and methylnitronaphthalenes to the vapor-phase mutagenicity of ambient air samples

1- and 2-Nitronaphthalene (NN) and the 14 methylnitronaphthalene (MNN) isomers were identified and quantified in ambient vapor-phase samples collected in Redlands, CA during moderate photochemical air pollution. The mutagenic activities of NN and MNN standards were determined using a microsuspension-preincubation modification of the Ames Salmonella bacterial reversion assay in strain TA98 without microsomal activation. The calculated contributions of the NNs and MNNs to the total vapor-phase ambient mutagenic activity were ∼ 18 and ∼ 32% for daytime and nighttime composite samples, respectively. Enhanced mutagenic activity in the nighttime sample was attributed to NN and MNN formation from nighttime N03 radical-initiated reactions of naphthalene and the methylnaphthalenes.

Reactions of Gas-Phase Phenanthrene under Simulated Atmospheric Conditions

Rate constants for the gas-phase reactions of phenanthrene with OH radicals, NO 3 radicals, and O 3 have been determined at 296±2 K and atmospheric pressure of air. The rate constants obtained (in cm 3 molecule -1 s -1 units) were (1.27±0.23)×10 -11 for the OH radical reaction, (1.2±0.4)×10 -13 for the NO 3 radical reaction under atmospheric conditions, and (4.0±1.0)×10 -19 for the O 3 reaction. These rate constants indicate that the OH radical and NO 3 radical reactions will be the dominant atmospheric loss processes for phenanthrene and that the overall atmospheric lifetime of gas-phase phenanthrene will be ≤1 day

Bioassay-directed fractionation of mutagenic PAH atmospheric photooxidation products and ambient particulate extracts

Simulated atmospheric gas-phase reactions of naphthalene, fluorene and phenanthrene have been carried out in an environmental chamber with bioassay-directed chemical analysis of the reaction products. Nitro-PAH were found to be the most significant mutagens formed from the reactions of naphthalene and fluorene. The mutagram (bar graph of mutagenic activity versus HPLC fraction) of the phenanthrene reaction products closely resembled that of an ambient air particulate extract with the most mutagenic activity being in a fraction more polar than that in which the nitro-PAH elute. Nitrophenanthrene lactones (nitro-6H-dibenzo[b,d]pyran-6-ones) were found to account for the observed activity of this polar fraction of the phenanthrene reaction products. It has been shown that the utilization of an environmental chamber with a known PAH-starting material and the ability to produce sufficient product for isomer-specific identifications of mutagens is a promising complement to bioassay-directed fractionation of ambient air particulate extracts.

OH radical-initiated gas-phase reaction products of phenanthrene

The OH radical-initiated gas-phase reaction of phenanthrene in the presence of NOx was investigated in a 6400-1 indoor all-Teflon chamber. Reaction products were identified by high-performance liquid chromatography fractionation and gas chromatography/mass spectrometry analysis. Identified reaction products were fluorenone, 2,2′-diformylbiphenyl, 1,4- and 9,10-anthraquinone, 9,10-phenanthrenequinone, 6H-dibenzo[b,d]pyran-6-one, three phenanthrol isomers, diphenic acid anhydride, 1-, 2-, 3-, 4- and 9-nitrophenanthrene, and 2- and 4-nitro-6H-dibenzo[b,d]pyran-6-one. Five other oxygenated products could only tentatively be characterized by their molecular formula. The identified compounds are compared with phenanthrene degradation products observed with other oxidants under simulated environmental conditions. The occurrence of identified compounds in ambient atmospheric samples is discussed.

Products of the OH radical-initiated gas-phase reaction of fluorene in the presence of NOx

Abstract The products of the OH radical-initiated gas-phase reaction of fluorene in the presence of NO x were investigated in a 6400 l all-Teflon chamber. Teh reaction products identified were fluorenone, 1-, 2-, 3- 4-nitrofluorene, three hydroxyfluorene isomers, three nitrofluorenone isomers and three hydroxynitrofluorene isomers. Of the reaction products identified, fluorenone was formed in the highest yield (9 ± 5%). The formation yields of the individual nitrofluorenes were in the order 3-nitrofluorene > 1- nitrofluorene > 4-nitrofluorene > 2-nitrofluorene, with the average 3-nitrofluorene yield being 1.4% and the total nitrofluorene yield being 2.5%. Diesel soot and ambient particulate matter showed relatively low concentrations of total nitrofluorenes when compared with the other nitro-PAH present. The measured ambient atmospheric concentrations of the nitrofluorenes were compared with levels expected on the basis of the nitrofluorene product yields from the OH radical-initiated reaction of fluorene.

Mutagenic activities of selected nitrofluoranthene derivatives in Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6

The mutagenic activities of novel nitrofluoranthene derivatives in Salmonella strains TA98, TA98NR and TA98/1,8-DNP6 (with and without S9 addition) are given. These derivatives were produced from the reactions of fluoranthene (FL) and its directly mutagenic 2- and 3-nitro derivatives with covalent dinitrogen pentoxide (N2O5) in CCl4 solution at ambient temperature. The influence of the addition of a nitro group on the observed activity of the resulting di- and tri-nitrofluoranthenes is discussed.

The mutagenicity of HPLC-separated vapor-phase and particulate organics in ambient air

Abstract A comparison of the Ames/ Salmonella activities of HPLC fractions of concurrently-sampled vapor-phase and particulate organics shows that the ambient mutagenicity concentration in the vapor-phase is comparable to that in the particulate matter.

Diurnal mutagenicity of airborne particulate organic matter adjacent to a heavily traveled West Los Angeles freeway

The bacterial mutagenicity of ambient particulate organic matter (POM) was measured for consecutive 3-hour time intervals over a 27-hour period in March 1983 at two sites on opposite sides of the heavily traveled San Diego Freeway (I-405) in West Los Angeles (WLA), California, the diurnal variations in the direct (not requiring S9 metabolic activation) mutagenic burden of airborne particulates and the magnitude of the mutagen doses observed at these sites were similar to those previously observed at a site just east of downtown Los Angeles (ELA). Highs (∼150 rev m−3) and lows (∼35 rev m−3) in mutagen densities occurred over short time intervals (a few hours) probably due to changes in emissions, mixing heights and wind speeds. Offshore air flows which drained the air basin between midnight and 0600 PST resulted in elevated mutagen density levels at the western edge of the Los Angeles Basjn. The incremental burden of direct mutagens in respirable POM attributable to freeway traffic reached 50 rev m−3 durin...