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Nitro-azabenzo[a]pyrenes, 1- or 3-nitro-azabenzo[a]pyrene and their N-oxides are nitrated derivatives of azabenzo[a] pyrene (ABP) containing nitrogen in the 6-position of benzo[a]pyrene (B[a]P). The nitro-ABP-N-oxides (ABPOs) were formed by reaction of ABP with excess HNO(3). These derivatives were noteworthy as potent mutagens for Salmonella strains, and were present in fine particles of diesel particulates. In this study, micronucleus induction in mice and chromosomal aberrations due to means of Chinese hamster lung fibroblast (CHL) cells were investigated to determine genotoxicity in order to define the relationship with the mutagenic potency of these derivatives. The induction of micronucleus polychromatic erythrocytes (MNPCEs) was dependent on the dose response of 10-40 mg for 3-N-6-ABP, and of 10-40 mg for 1-N-6-ABP, and in addition, 1- and 3-N-6-ABPOs markedly induced MNPCEs in a dose range of 10-400 mg and from 1 to 80 mg, respectively, when the compound was intraperitoneally administrated in two mice at each dose. The results show that of the four compounds, 3-N-6-ABPO demonstrated a marked increase in MNPCES: On the other hand, chromosomal aberrations of the four compounds were investigated by the duplicate tests using CHLS: The results after a 48 h treatment induced aberrations of the chromatid type, chromatid breaks and exchanges for 1- and 3-N-6-ABP, and mainly chromatid exchanges for 1- and 3-N-6-ABPO. The frequency of chromosomal aberrations associated with nitro substitution on the ABPO structure. Chromosomal aberrations of nitro derivatives of ABPO substituted at the 3-position on the structure were more potent than those at the 1-postion. N-oxide derivatives have been found to be reduced to anion radicals much more easily than azaB[a]P and its nitro derivatives. This suggests that the electrochemical reduction of the chemicals plays an important role in the metabolic activation of nitrated B[a]P derivatives.

Our earlier study revealed that 1- and 3-nitrobenzo[a]pyrene (NBP), 1,6- and 3,6-dinitrobenzo[a]pyrene (DNBP), nitrated derivatives of benzo[a]BP (BP), are present in the environment. These derivatives are potent mutagens for Salmonella tester strains and we have preliminarily reported them to be carcinogenic in F344/DuCrj rats. In this study, the tumorigenic action of 1- and 3-NBP, 1.6- and 3,6-DNBP, and BP induced by subcutaneous injection into rats was found to differ according to the NO2-substitution in the BP structure. The chemicals were suspended in equal volumes of beeswax and tricaprylin, and rats were subcutaneously injected with single doses of 500, 1000, and 2000 microg for 1- and 3-NBP, and of 8, 40, 200, and 1000 microg for 3,6- and 1,6-DNBP, and BP as a positive control. 3,6-DNBP and BP induced tumors in a dose-dependent manner at the injection site. Rats given 1000 microg of 3,6-DNBP (2924 nmol) and BP (3968 nmol) developed subcutaneous tumors at the rate of 70 and 80%, respectively, and those given a minimum dose of 23 nmol for 3.6-DNBP and 32 nmol for BP per rat developed tumors at a rate of 4.8 and 18.2%, respectively. However, rats given 500 and 1000 microg of 1- and 3-NBP did not develop any tumors while those given a high dose, 2000 microg, of each chemical developed tumors at only one of ten animals used. It was concluded, therefore, that these chemicals are weak carcinogens. Histologically, most of the tumors were malignant fibrous histiocytomas. Rats given various doses of 1,6-DNBP did not develop any tumors at the injection site. The failure of 1,6-DNBP to induce tumors may involve its metabolites because of the lower mutagenicity of its reduction products, 1-nitroso-6-NBP and 1-amino-6-NBP. It is suggested, therefore, that tumorigenicities of NBPs and DNBPs differ according to the NO2-substitution on the chemical structure, which may be due to the possible nitroreduction of the chemicals.

Fuyuan Country, in Yunnan Province, China has an extremely high lung cancer mortality both in males and non-smoking females. Out of 5768 deaths, 588 patients died of malignant diseases. Lung cancer was the number one cause of death among malignant diseases both in males and females. The rate of lung cancer death to the whole of malignant diseases was 56.2% for males and 55.0% for females. Indoor soot and combustion emission derived from smoky coal produced in northern Fuyuan exhibited high mutagenic activities against Salmonella typhimurium TA98 strain in Ames test. Resected lung tissues derived from the patients with lung cancer in Fuyuan contained significantly higher concentrations of benzo(a)pyrene than those in Japan, both in males and females (i.e., 608.7 +/- 477.1 pg/dry weight for samples of the patients in Fuyuan, 180.1 +/- 104.5 for Japanese non-smokers, and 207.5 +/- 98.8 for Japanese heavy smokers, respectively). These results suggest that mutagenic chemicals contained in coal as well as indoor environment may have a great influence on lung carcinogenesis in Fuyuan, Yunnan Province, China.

Mutagens in the semivolatile phase of airborne particulate matter, diesel and gasoline engine emissions were investigated using chemical and biological assays. The previously unknown mutagens, 1-(3-)nitro-6-azabenzo[a]pyrenes (1-N-6-ABP and 3-N-6-ABP) and 1-(3-)nitro-6-azabenzo[a]pyrene-N-oxides (1-N-6-ABPO and 3-N-6-ABPO), were detected in the semivolatile phase, which was adsorbed onto XAD-4 resin combined with a Teflon-coated fibre filter. Dichloromethane extracts of materials adsorbed onto XAD-4 resin were divided into acidic, neutral and basic by liquid-liquid separation. These chemicals in the basic fraction were the major mutagens in the semivolatile phase when they were bioassayed using Salmonella typhimurium TA98 in the absence of S9 mix; the mutagenicity of the basic fraction contributed at the rate of 42.9-68.8% of that of crude extracts for airborne, diesel and gasoline emission materials. As the mutagens were found to be difficult to analyse by gas chromatography (because of their probable absorption onto the packing) they were purified by HPLC and analysed by mass spectrometry. The concentrations of 1-N-6-ABP, 3-N-6-ABP, 1-N-6-ABPO and 3-N-6-ABPO detected were 1.1, 1.2, 0.8 and 0.3 ng/g, respectively, of materials in the airborne sample, and 4.9, 7.7, 2.2 and 3.8 ng/g, respectively, of materials in the diesel emission. Only 1-N-6-ABP (3.4 ng/g) and 3-N-6-ABP (4.9 ng/g) were detected in the semivolatile phase of the gasoline engine emission.(ABSTRACT TRUNCATED AT 250 WORDS)

To elucidate a relationship between lung cancer and tumor induction of environmental chemicals, the presence of 1-nitropyrene (1-NP) and benzo[a]pyrene (B[a]P) in 137 Japanese (97 male and 40 female), and 21 Chinese lung specimens was examined by HPLC, and GC-MS and environmental exposure discussed. Mortality due to lung cancer in Fuyuan County, China, is much higher than that of other cancers. We investigated 21 patients who were residents of Fuyuan County. All were female aged 28-64 years and were non-smoking farmers and cooks. The histological features of the tumors were adenocarcinoma, squamous cell carcinoma and small cell carcinoma. The incidence of cancer was due to inhaling soot from the combustion of coal used for cooking and indoor heating. The polycyclic aromatic hydrocarbons, chrysene, benzo[k]fluoranthene, B[a]P, benzo[g,h,i]perylene and pyrene, but not their nitrated derivatives, were detected in substantial amounts in the resected lungs. These mutagens and carcinogens normally originate in combustion products of coal, and are discussed as the possible initiators of the tumors in the lungs of these patients. All the Japanese lung specimens were also obtained from non-smokers. The concentrations of 1-NP averaged 21.3 +/- 12.4 and 5.9 +/- 2.4 pg/g of Japanese and Chinese samples respectively. The concentrations of B[a]P averaged 180.2 +/- 103.7 and 608.7 +/- 477.1 pg/g of Japanese and Chinese samples respectively. Thus, Japanese and Chinese lung specimens were mainly contaminated by 1-NP and B[a]P, respectively. Typical tissues from a carcinomatous human lung were examined. The patient was a 64-year-old Japanese male non-smoker and farmer who had raised chickens over a period of 40 years. The histological features of the tumor were those of keratinizing squamous cell carcinoma. 1-Nitropyrene, 1-nitro-3-hydroxypyrene, 1,3-dinitropyrene and chrysene were detected at concentrations of 0.11, 0.036, 0.095 and 0.16 ng respectively per gram of lung tissue. This cancer was due to long-term exposure to the combustion products of heavy oil used in a chicken house.

The mutagenicity of nitrated benzo[a]pyrene (BP) and the related compounds, 1- and 3-nitrobenzo[a]pyrene (NBP), 1- and 3-nitro-6-cyanobenzo[a]pyrene (N-6-CBP), 1- and 3-nitro-6-azabenzo[a]-pyrene (N-6-ABP), 1- and 3-nitro-6-azabenzo[a]-pyrene-N-oxide (N-6-ABPO) and 1,6- and 3,6-dinitrobenzo[a]-pyrene (DNBP), was investigated. The mutagenic activities of 3-N-6-CBP and 3-N-6-ABP were 117 and 76 times, respectively, that of 3-NBP. In addition, 3,6-DNBP was more mutagenic than 1,6-DNBP. It is suggested that the mutagenic activation differs with the position of NO2 substitution in the chemical structure. A nitro derivative with NO2 substitution at the 3 position of the aromatic ring of BP was more mutagenic than that with the substitution at the 1 or 6 position. The reducibility of DNBPs was then determined by detecting 1- or 3-amino-6-nitrobenzo[a]pyrene (A-6-NBP), a metabolite of DNBP; 3,6- and 1,6-DNBP were reduced to 3- and 1-A-6-NBP at frequencies of 958 +/- 26 and 79 +/- 8, respectively, pmole per mg of protein, when the compound was incubated anaerobically with rat liver S9 mix at 37 degrees C for 15 min. NO2 substituted at the 3 position of the aromatic ring of BP was readily reduced by a microsome enzyme to form an amino derivative. The result suggests that these compounds have a structure-activity relationship between mutagenicity and NO2 substitution of BP.

3,9- and 3,7-Dinitrofluoranthene (3,9- and 3,7-DNF), 3-nitrofluoranthene (3-NF) and benzo[a]pyrene (B[a]P) were tested for pulmonary carcinogenicity by intrapulmonary implantation of the compounds into rat lung. These chemicals were given in various doses as suspensions in beeswax-trycaprylin and the animals were observed for 100 weeks. The control group received no drugs. The incidences of lung tumors were 19/21 (90.5%), 7/10 (70%) and 1/10 (10%) in rats treated with 200, 100 and 50 micrograms of 3,9-DNF, 4/9 (44.4%), 3/10 (30%) and 0/10 (0%) in rats treated with 200, 100 and 50 micrograms of B[a]P, 12/22 (54.5%) in rats treated with 200 micrograms of 3,7-DNF and 1/20 (5%) in rats treated with 1000 micrograms of 3-NF respectively. No lung tumors were found in control rats. The incidence of lung tumors induced by 3,9-DNF was twice as high as that induced by B[a]P, when the equivalent dose levels of the two compounds were compared. Histologically, most of the tumors induced by 3,9- and 3,7-DNF and B[a]P were squamous cell carcinomas.

3,6-Dinitrobenzo[a]pyrene, a new mutagen, was detected in airborne particulates collected in Santiago (Chile). The quantity of the compound in the airborne particulates was very small, accounting for 0.01 micrograms/g of total particulates (0.002 ng/m3 of air) at the lowest concentration. It was found that 3,6-dinitrobenzo[a]pyrene is readily decomposed by UV irradiation at 312 nm. The decomposed product was identified as 3-nitrobenzo[a]pyrene-6-quinone by means of mass spectrometry and proton nuclear magnetic resonance analysis. The mutagenicity of 3,6-dinitrobenzo[a]pyrene was 137,000 revertants/nmole for Salmonella typhimurium strain TA98, less than that for strain TA98/1,8-DNP6, an acetyltransferase-deficient mutant, and more than that for strain YG1024, an acetyltransferase-rich mutant.