Comparison of Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Airborne and Automobile Exhaust Particulates

Contributions of long-range transport from the Asian continent and local emissions on atmospheric PM2.5, polycyclic aromatic hydrocarbons, and their nitro-derivatives in Kanazawa and Noto Peninsula, Japan

This study collected samples of particulate matter that are 2.5 μm or less in diameter (PM2.5) in Kanazawa, Japan, and Noto Peninsula located 100 km north on the windward side of the westerlies from the Asian continent and characterized the extent of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) pollution in Kanazawa. Emission areas and specific sources of PM2.5 and of PAHs and NPAHs were clarified via back-trajectory analysis and the NP-method, respectively. The results indicate that during 2020 and 2021, most PAHs (93%) in Kanazawa were transported from the Asian continent by westerlies and that the main source was coal and biomass combustion. The presence of NPAHs in Kanazawa was caused by a mixture of transport from the Asian continent (53%) and local emissions (47%), with the main source of the latter being from vehicles. Although the content of combustion-derived particulates (Pc) was <2.4% of PM2.5 in Kanazawa, this showed a similar seasonal variation (winter > summer) to that of PAHs. The contribution of Pc transported from the Asian continent exceeded that of locally emitted Pc. The current situation of Kanazawa is considerably different from that of 1997, when local vehicles were the main source of pollution.

Synthesis of Ni/NiAlOx Catalysts for Hydrogenation Saturation of Phenanthrene

The saturation of octahydrophenanthrene was the rate-determining step in the hydrogenation process from phenanthrene to perhydrophenanthrene, which was due to the steric hindrance and competitive adsorption of octahydrophenanthrene. In this work, a series of Ni/NiAlO_x catalysts with a uniform electron-deficient state of Ni derived from the nickel aluminate structure was synthesized to overcome the disadvantage of noble catalyst and the traditional sulfided catalysts in the saturation hydrogenation process of phenanthrene. Results showed that the catalyst calcinated at 650°C possessed more Ni²⁺ (∼98%) occupying octahedral sites and exhibited the highest r_obs (1.53 × 10^-3 mol kg^-1 s^-1) and TOF (14.64 × 10^-3 s^-1) for phenanthrene hydrogenation. Furthermore, its ability to overcome steric hindrance and promote the rate-determining step was proven by octahydrophenanthrene hydrogenation. Comparing the evolution of hydrogenation activity with the change in the electronic structure of surface Ni sites, it was shown that the increase of metallic electron deficiency hindered the π-back bonding between surface Ni and aromatic rings, which was unfavorable for aromatic adsorption. As a result, the phenanthrene hydrogenation saturation performance can be enhanced by stabilizing the electron-deficient state of surface Ni on an optimal degree.

Polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in five East Asian cities: Seasonal characteristics, health risks, and yearly variations

Total suspended particulate matter and fine particulate matter were collected in five East Asian cities (Sapporo, Sagamihara, Kirishima, Shenyang, and Vladivostok) during warm and cold periods from 2017 to 2018. Nine polycyclic aromatic hydrocarbons (PAHs) and three nitro-polycyclic aromatic hydrocarbons (NPAHs) were detected by high-performance liquid chromatography with a fluorescence detector. The average concentrations of ∑PAHs and ∑NPAHs differed significantly both temporally and spatially and were the lowest in Kirishima during the warm period (∑PAHs: 0.11 ± 0.06 ng m^-3; ∑NPAHs: 1.23 ± 0.96 pg m^-3) and the highest in Shenyang during the cold period (∑PAHs: 49.7 ± 21.8 ng m^-3; ∑NPAHs: 357 ± 180 pg m^-3). The average total benzo[a]pyrene-equivalent concentrations were also higher in Shenyang and Vladivostok than in Japanese cities. According to the results of source apportionment, traffic emissions impacted these cities in both the warm and cold periods, whereas coal combustion-generated effects were obvious in Shenyang and Vladivostok during the cold period. Furthermore, PAHs and NPAHs originating from the Asian continent, including Shenyang and Vladivostok, exerted some influence on Japanese cities, especially in the cold period. Compared to Japanese cities and Vladivostok, yearly variations in ∑PAHs and 1-nitropyrene in Shenyang showed that their concentrations were considerably lower than those reported in past studies, indicating the positive effects of air pollutant control policies in China. These results not only describe the current characteristics and yearly variations of PAHs and NPAHs in typical urban cities in East Asia but also, more importantly, reveal that the effects of the East Asian monsoon play an important role in the analysis of atmospheric behaviours of PAHs and NPAHs. Furthermore, this study supports the role of multinational cooperation to promote air pollution control in East Asia.

Emission characteristics and temporal variation of PAHs and their derivatives from an ocean-going cargo vessel

Polycyclic aromatic hydrocarbons (PAHs), nitro- (NPAHs) and oxy-derivatives (OPAHs) are of considerable concern due to their toxicity and carcinogenic hazards. Ships are recognized as an important emission source of these compounds. Marine diesel oil (MDO) and heavy fuel oil (HFO) are the two most commonly used fuels. The emission characteristics and toxicities of PM_2.5-bound PAHs, NPAHs and OPAHs due to HFO and MDO combustion in atypical ocean-going vessel were investigated. The EF variability of polycyclic aromatic compounds (PACs) varied considerably with the fuel formulation (HFO and MDO) and engine loading (20%-100%). The concentration of ΣPACs was 0.63 mg/kWh for MDO and ranged from 2.14 to 9.80 mg/kWh for HFO. Compared to HFO-20%, the EFs of ΣPAHs, ΣNPAHs and ΣOPAHs from MDO-20% were reduced by 97%, 77% and 73%, respectively. As identified through the coefficient of divergence, the profile of HFO-20% was notably different from those under the other three engine loadings for HFO. In addition, the emissions of ΣPAHs and ΣOPAHs showed a significant correlation with PM_2.5, while they were relatively weak for ΣNPAHs. However, the CO and PAC emissions were not highly correlated. Furthermore, the BaP_eq-ΣPAHs values were 0.010 mg/g for MDO and ranged from 0.092 mg/g to 0.306 mg/g for HFO, and the reduction ranged from 89% to 97% by substituting MDO for HFO. These data highlight the importance of improving fuel quality in close proximity to port areas and are useful for enhancing relevant databases.

Recent Occurrence of PAHs and n-Alkanes in PM2.5 in Seoul, Korea and Characteristics of their Sources and Toxicity

Polycyclic Aromatic Hydrocarbons (PAHs) and n-alkanes in particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) were quantified at Seoul, Korea in 2018. The seasonal differences in the total concentration of PAHs and n-Alkanes were clear, where winter showed a higher concentration than that of summer. Compared to the PAHs measurements in 2002 at Seoul, the sum of PAHs concentrations in 2018 were reduced from 26.6 to 5.6 ng m-3. Major sources of the observed PAHs and n-alkanes were deduced from various indicators such as diagnostic ratios for PAHs and Cmax, CPI, and WNA (%) indices for n-alkanes. It was found that in winter coal and biomass combustions, and vehicular exhaust were major sources, while, in summer vehicular exhaust was major source. In addition, in winter, major emission sources were located outside of Seoul. The health effect from the recent level of PAHs was estimated and compared to the previous studies observed in Seoul, and it was found that, recently, the toxicity of PAHs in PM2.5 was significantly decreased, except for in the winter.

Characterization of PM2.5-bound polycyclic aromatic hydrocarbons and their derivatives (nitro-and oxy-PAHs) emissions from two ship engines under different operating conditions

Emissions from ship exhaust have been recognized as an important source of air pollution in coastal areas. To investigate the impacts of engine type, fuel and operating conditions on polycyclic aromatic compounds (PACs) emissions, particle matter (PM_2.5) samples emitted from an inland-river bulk freighter (BF) using marine diesel oil (MDO) and an ocean-going passenger vessel (PV) using heavy fuel oil (HFO) were collected under five operation conditions (preheating, leaving, cruising, entering and berthing). The concentrations of 17 polycyclic aromatic hydrocarbons (PAHs), 12 nitro-PAHs (NPAHs) and 4 oxygenated-PAHs species were determined. The concentrations of ΣPAHs, ΣNPAHs and ΣOPAHs measured on the BF and PV exhausts ranged from 1.95 to 417 μg/m³, 86.5 to 6.89 × 10³ ng/m³ and 2.00-102 μg/m³, respectively. Both ships showed a high proportion of four-ring PAHs, while the BF had more three-ring PAHs (34.00-70.38%) and the PV had more five-ring PAHs (30.02-35.95%). The calculation of indicatory PACs are able to increase the precision of source appointment. The emission factors (EFs) of PACs under maneuvering (including preheating, leaving, entering and berthing) was much higher than those under cruising, which might be due to the engine load, fuel consumption, and secondary reactions. Compared with HFO, combustion with MDO decreased the power-based ΣPAH EFs by 82-99%, power-based ΣNPAH EFs by 86-98%, and power-based ΣOPAHs EFs by 50-82%. These data highlight the importance of quantifying and monitoring ship emissions in close proximity to port area, and are useful for enhancing the relevant databases and improving the accuracy of ship emission inventories.

Occurrence of the potent mutagens 2- nitrobenzanthrone and 3-nitrobenzanthrone in fine airborne particles

Polycyclic aromatic compounds (PACs) are known due to their mutagenic activity. Among them, 2-nitrobenzanthrone (2-NBA) and 3-nitrobenzanthrone (3-NBA) are considered as two of the most potent mutagens found in atmospheric particles. In the present study 2-NBA, 3-NBA and selected PAHs and Nitro-PAHs were determined in fine particle samples (PM 2.5) collected in a bus station and an outdoor site. The fuel used by buses was a diesel-biodiesel (96:4) blend and light-duty vehicles run with any ethanol-to-gasoline proportion. The concentrations of 2-NBA and 3-NBA were, on average, under 14.8 µg g⁻¹ and 4.39 µg g⁻¹, respectively. In order to access the main sources and formation routes of these compounds, we performed ternary correlations and multivariate statistical analyses. The main sources for the studied compounds in the bus station were diesel/biodiesel exhaust followed by floor resuspension. In the coastal site, vehicular emission, photochemical formation and wood combustion were the main sources for 2-NBA and 3-NBA as well as the other PACs. Incremental lifetime cancer risk (ILCR) were calculated for both places, which presented low values, showing low cancer risk incidence although the ILCR values for the bus station were around 2.5 times higher than the ILCR from the coastal site.

Environmental Behaviors and Toxicities of Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons

Airborne particulate matter (PM) has been collected at four cities in Japan starting in the late 1990s, at five or more major cities in China, Korea and Russia starting in 2001 and at the Noto Peninsula starting in 2004. Nine polycyclic aromatic hydrocarbons (PAHs) and eleven nitropolycyclic aromatic hydrocarbons (NPAHs) were determined by HPLC with fluorescence and chemiluminescence detections, respectively. Annual concentrations of PAHs and NPAHs were in the order, China>Russia≫Korea=Japan, with seasonal change (winter>summer). During the observation period, concentrations of PAHs and NPAHs in Japanese cities significantly decreased but the increases in the PAH concentration were observed in Chinese and Russian cities. Concentrations of PAHs and NPAHs were higher in the Northern China than those in the Southern China. At the Noto peninsula, which is in the main path of winter northwest winds and a year-round jet stream that blow from the Asian continent to Japan, the concentrations were high in winter and low in summer every year. A cluster analysis and back trajectory analysis indicated that PAHs and NPAHs were long-range transported from Northeastern China, where coal burning systems such as coal-heating boilers are considered to be the major contributors of PAHs and NPAHs. A dramatic change in atmospheric concentrations of PAHs and NPAHs in East Asia suggests the rapid and large change of PM2.5 pollution in East Asia. Considering the adverse health effects of PM2.5, continuous monitoring of atmospheric PAHs and NPAHs is necessary in this area.

Detection of DNA damage in fish Oreochromis mossambicus induced by co-exposure to phenanthrene and nitrite by ESI-MS/MS

BACKGROUND, AIM, AND SCOPE

Mutagenic nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) have been known to arise in the environment through direct emissions from combustion sources and nitration of PAHs, primarily in the atmosphere. In the marine environment, PAHs are one of the classic anthropogenic organic pollutants, while nitrite (NO(2)(-)) is produced naturally via various biological processes like imbalance in nitrification/denitrification or eutrophication and subsequent oxygen depletion from an oversupply of nutrients. In this paper, we report the formation of PAH-DNA adducts in fish contaminated with PAHs and exposed to NO(2)(-) in the ambient water. Electrospray ionization tandem mass spectrometric (ESI-MS/MS) analysis of the bile of the euryhaline fish Oreochromis mossambicus exposed simultaneously to field relevant sublethal concentrations of phenanthrene and NO(2)(-) and collision-induced dissociation of selected ions revealed the presence of DNA-PAH adducts. The present study indicates that, although several high sensitivity techniques have been developed for the analysis of PAH derived DNA adducts, MS/MS has emerged as a powerful tool in the detection and structure elucidation of DNA adducts.

MATERIALS AND METHODS

Juvenile O. mossambicus from a local estuarine fish farm were used with increasing frequency for carcinogenicity testing and comparative cancer research. The fish were exposed to the alkylating agent phenanthrene in the presence of NO(2)(-). Composite untreated bile samples after dilution with methanol: water (1:1; v/v) were analyzed by ESI-MS.

RESULTS

Several adducts could be evidenced in the bile by MS/MS. Deoxyadenosine/deoxyguanosine having a mass in the range of 450-650 amu is detected. In addition, a segment of modified dinucleotide with a mass that corresponds to a dimer consisting of a modified guanosine and a normal guanosine has also been identified in the bile.

DISCUSSION

The formation of certain types of DNA adducts is a crucial step in the induction of cancer and a primary stage in mutagenesis. Phenanthrene injected by i.p. route led to the transformation of phenanthrene to N-formyl amino phenanthrene-N(6)-deoxyadenosine adduct, whereas the fish co-exposed to phenanthrene and ambient nitrite metabolizes PAH to mono-, di- as well as trinitro derivatives, which then react with DNA leading to the formation of mainly modified guanosine and adenosine adducts. In the present investigation, dinitrophenanthrene diol epoxide (DNPDE) adduct with guanosine (m/z 587) seems to be the dominant adduct in the mixture, and its presence is shown first as a comparatively less stable adduct, which decomposes to give a more stable N(2) adduct (m/z 567).

CONCLUSIONS

MS/MS has proved to be useful in the rapid determination and discrimination of structurally different phenanthrene/derivatives DNA adducts in a complex mixture of fish bile co-exposed to phenanthrene and nitrite. However, the nature of metabolites formed is likely determined by the route of PAH administration, and there is a need to further define the early biochemical events of carcinogenesis in these species.

RECOMMENDATIONS AND PERSPECTIVES

DNA adduct analysis in fish bile offers a promising approach to study the risk of potentiation of anthropogenic chemicals into genotoxic compounds in the presence of nitrite in the marine environment. We believe this is the first report on the formation of DNA-phenanthrene adducts on co-exposure of the fish to PAH and nitrite.

Nitrated Polycyclic Aromatic Hydrocarbons in the Environment: Formation, Occurrences and Analysis

A review is presented on the formation and occurrence in the atmosphere of nitrated polycyclic aromatic hydrocarbons. Some analytical methodologies (covering various matrices) are also considered.

Determination of single particle mass spectral signatures from light-duty vehicle emissions

In this study, 28 light-duty gasoline vehicles (LDV) were operated on a chassis dynamometer at the California Air Resources Board Haagen-Smit Facility in El Monte, CA. The mass spectra of individual particles emitted from these vehicles were measured using aerosol time-of-flight mass spectrometry (ATOFMS). A primary goal of this study involves determining representative size-resolved single particle mass spectral signatures that can be used in future ambient particulate matter source apportionment studies. Different cycles were used to simulate urban driving conditions including the federal testing procedure (FTP), unified cycle (UC), and the correction cycle (CC). The vehicles were selected to span a range of catalytic converter (three-way, oxidation, and no catalysts) and engine technologies (vehicles models from 1953 to 2003). Exhaust particles were sampled directly from a dilution and residence chamber system using particle sizing instruments and an ATOFMS equipped with an aerodynamic lens (UF-ATOFMS) analyzing particles between 50 and 300 nm. On the basis of chemical composition, 10 unique chemical types describe the majority of the particles with distinct size and temporal characteristics. In the ultrafine size range (between 50 and 100 nm), three elemental carbon (EC) particle types dominated, all showing distinct EC signatures combined with Ca, phosphate, sulfate, and a lower abundance of organic carbon (OC). The relative fraction of EC particle types decreased as particle size increased with OC particles becoming more prevalent above 100 nm. Depending on the vehicle and cycle, several distinct OC particle types produced distinct ion patterns, including substituted aromatic compounds and polycyclic aromatic hydrocarbons (PAH), coupled with other chemical species including ammonium, EC, nitrate, sulfate, phosphate, V, and Ca. The most likely source of the Ca and phosphate in the particles is attributed to the lubricating oil. Significant variability was observed in the chemical composition of particles emitted within the different car categories as well as for the same car operating under different driving conditions. Two-minute temporal resolution measurements provide information on the chemical classes as they evolved during the FTP cycle. The first two minutes of the cold start produced more than 5 times the number of particles than any other portion of the cycle, with one class of ultrafine particles (EC coupled with Ca, OC, and phosphate) preferentially produced. By number, the three EC with Ca classes (which also contained OC, phosphate, and sulfate) were the most abundant classes produced by the nonsmoking vehicles. The smoker category produced the highest number of particles, with the dominant classes being OC comprised of substituted monoaromatic compounds and PAHs, coupled with Ca and phosphate, thus suggesting used lubricating oil was associated with many of these particles. These studies show, by number, EC particles dominate gasoline emissions in the ultrafine size range particularlyforthe lowest emitting newer vehicles, suggesting the EC signature alone cannot be used as a unique tracer for diesels. This represents the first report of high time- and size-resolved chemical composition data showing the mixing state of nonrefractory elements in particles such as EC for vehicle emissions during dynamometer source testing.

Direct-acting mutagenicity of extracts of coal burning-derived particulates and contribution of nitropolycyclic aromatic hydrocarbons

Benzene-ethanol extracts from particulates produced by coal burning were separated into four fractions by silica-gel column chromatography using n-hexane (240 ml), n-hexane-dichloromethane (3:1, v/v) (200 ml), dichloromethane (200 ml) and methanol (450 ml), as the corresponding eluents. The mutagenicity of each fraction was assayed by the Ames test using the Salmonellatyphimurium YG1024 strain. The nitropolycyclic aromatic hydrocarbons (NPAHs) of each fraction were assayed by high-performance liquid chromatography with chemiluminescence detection. The highest activity was observed in the n-hexane-dichloromethane fraction (Fr. 2). The mutagenic contribution of this fraction was 69.9% of the total of the four fractions. Ten of 11 NPAHs detected were in Fr. 2 and one (1-nitropyrene) was most concentrated in Fr. 3. Among the NPAHs examined, 3-nitrobenzanthrone made the largest mutagenic contribution. This is the first report of detection of 3-nitrobenzanthrone in coal burning-derived particulates.

Development of an analytical method for polycyclic aromatic hydrocarbons and their derivatives

The possibilities of utilising pressurised liquid extraction for five nitro-polycyclic aromatic hydrocarbons from an inert matrix are shown. Different extraction temperatures and pressures were tested. The highest recoveries were obtained at extraction pressure 14 MPa and temperature 100 C. Separation of non-polar, aromatic and polar fractions by the silica gel column chromatography is shown. n-Hexane, cyclohexane and dichloromethane as a solvent were tested. The best separations of monitored fractions were obtained, when extract was dissolved in cyclohexane. Non-polar and aromatic fractions eluted together when the extract was dissolved in dichloromethane.

Antiandrogenic activity of extracts of diesel exhaust particles emitted from diesel-engine truck under different engine loads and speeds

To clarify the alteration of androgenic and antiandrogenic activities by diesel engine conditions, we collected diesel exhaust particles (DEP) samples emitted from a diesel-engine truck under different conditions of engine loads and vehicle speeds, and DEP extract (DEPE) samples were prepared from each. The androgenic and antiandrogenic activities of the DEPE samples were examined using a prostate specific antigen (PSA) promoter-luciferase reporter gene assay in PC3/AR human prostate cancer cells. While all DEPE samples did not exhibit androgenic effects, the antiandrogenic effects were enhanced by higher engine load but not by higher vehicle speed. In this study, significant correlations between antiandrogenic and aryl hydrocarbon receptor (AhR) agonistic activities were demonstrated in PC3/AR cells by 16 polycyclic aromatic compounds and beta-naphthoflavone. Yeast two-hybrid assay and cytochrome P450 (CYP) 1A1 promoter-luciferase reporter gene assay showed that the antiandrogenic constituents acting as androgen receptor (AR) antagonists and AhR agonists were increased by only the higher engine load. In conclusion, the antiandrogenic effects of DEPE samples were enhanced by a higher engine load which resulted in DEPC samples with elevated AhR agonistic and AR antagonistic activities.

Improvement of an automatic HPLC system for nitropolycyclic aromatic hydrocarbons: removal of an interfering peak and increase in the number of analytes

An automatic HPLC system for analyzing nitropolycyclic aromatic hydrocarbons (NPAHs, nitroarenes) in airborne particulates was previously described (Anal. Chim. Acta, 2001, 445, 20). Some problems with this system were that it generated a peak originating from an ascorbic acid solution that elutes at a retention time close to that of 1,6-dinitropyrene (DNP), and that it was able to analyze only 1,3-, 1,6-, 1,8-DNPs and 1-nitropyrene (I-NP). Here, we describe an improved system that effectively removes the interfering peak by introducing an ODS column just after the pump for the ascorbic acid solution, and which is capable of analyzing several additional compounds (2-, 4-NPs, 2-nitrofluorene. 6-nitrochrysene, 7-nitrobenz[a]anthracene, 3-nitroperylene and 6-nitrobenzo[a]pyrene etc.). The improved sensitivities were achieved by concentrating the compounds in a benzene-ethanol extract from airborne particulates, by increasing the loading time of the sample solution from 20 to 38 min, and by increasing the flow rate of an ascorbic acid solution from 1.3 to 1.8 mL/min.

Induction of cytochrome P450 1B1 in lung, liver and kidney of rats exposed to diesel exhaust

We have shown previously that diesel exhaust particle (DEP) extracts (DEPE) and 1-nitropyrene were genotoxically activated by human cytochrome P450 1B1 in SOS/umu assay. In this study, the in vivo induction of P450 family 1 enzymes in rats by exposure to diesel exhaust was investigated with regard to mRNA levels, P450 enzyme content, drug oxidation activities in the microsomes and umu gene expression of typical P450 substrates and DEPE itself catalyzed by the microsomes. Male Fischer 344 rats (4 weeks old) were exposed to 0.3 and 3.0 mg/m(3) DEP for 12 h per day for 4 weeks; the former dose corresponded to the typical daily airborne particle concentration. The levels of mRNA of rat P450 1B1 and P450 1A1 in the lung and liver were significantly increased 1.1-1.4-fold by exposure to 0.3 mg/m(3) DEP. Diesel exhaust particle extracts induced umu gene expression in Salmonella typhimurium TA1535/pSK1002 in the absence of a functional P450 system and were further activated by human recombinant P450 1B1. Using an O-acetyltransferase overexpressing Salmonella strain, genotoxic activation of P450 1B1 marker chemicals (1-nitropyrene, 1-aminopyrene and DEPE) by lung, liver and kidney microsomes was increased 1.7-4.2-, 1.4-1.5- and 1.0-1.3-fold, respectively, by exposure to 0.3 mg/m(3) DEP. Activation of 3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole (Trp-P-1; marker for P450 1A1) by lung microsomes and the P450 1A2 content in liver microsomes were slightly increased by exposure to 3.0 mg/m(3) DEP. This is the first report to suggest that typical daily contaminant levels (0.3 mg particle/m(3)) of diesel exhaust can induce P450 1B1 in rats and that the induced P450 1B1 may catalyze the genotoxic activation of DEP.

Metabolic activation of carcinogenic 1-nitropyrene by human cytochrome P450 1B1 in Salmonella typhimurium strain expressing an O-acetyltransferase in SOS/umu assay

Metabolic activation of 1-nitropyrene (1-NP) by human cytochrome P450 (P450) family 1 enzymes co-expressed with NADPH-cytochrome P450 reductase (NPR) in Escherichia coli membranes was investigated. 1-NP induced umu gene expression in Salmonella typhimurium TA1535/pSK1002 in the absence of any P450 system, but the activities were influenced by the levels of bacterial O-acetyltransferase (OAT) and nitroreductase. Metabolic activation of 1-NP by human P450 1B1/NPR membranes was observed and was influenced by the levels of OAT levels in tester strains. Metabolic activation of 1-NP (0.3microM) by P450 1B1 was 750 umu units/min/nmol P450 1B1 in an OAT-overexpressing strain NM2009. The metabolic activation of 1-NP (3-30microM) was similar (approximately 300 umu units/min/nmol P450 1B1) using TA1535/pSK1002 or OAT-deficient strain NM2000. P450 1B1 had the highest catalytic activities among P450 family 1 enzymes for the activation of 1-aminopyrene (1-AP) in the OAT-overexpressing strain NM2009, suggesting nitrenium ion formation via N-hydroxylation/O-acetylation. High-performance liquid chromatography (HPLC) analyses revealed the formation of 1-nitropyrene-6-ol and also 1-nitropyrene-3-ol, 1-nitropyrene-8-ol, and trans-4,5-dihydroxy-4,5-diol-1-nitropyrene from 1-NP (10microM), catalyzed by P450 1B1. These results indicate that 1-NP can be activated by human P450 1B1 to a genotoxic agent by nitroreduction/O-acetylation at low substrate concentrations and probably by epoxidation (independent of OAT) at high concentrations.