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Exposure to nanomaterials (NM) during sensitive developmental stages may predispose organisms to diseases later in life. However, direct translocation of NM from mother to fetus through the placenta is limited. The present study tests the hypothesis that pulmonary exposure to NM and NM-induced response, such as inflammation during gestation, leads to secondary effects in the fetus. Time-mated C57BL/6BomTac mice were exposed by intratracheal instillation to vehicle (Nanopure water) or one of three concentrations (2.75, 13.5 or 67 μg in 40 μl Nanopure water) of carbon black Printex 90 (CB) on gestational days 7, 10, 15 and 18, to final cumulative doses of 11, 54 or 268 μg/animal. Samples from a subset of male and female newborns were collected on postnatal day 2 (4 days after the last maternal exposure) and from dams 26 to 27 days post-exposure (post-weaning period). Histopathology, DNA microarrays, pathway-specific RT-PCR arrays, focussed RT-PCR, and tissue protein analysis were employed to characterize pulmonary response in dams exposed to CB during pregnancy. Hepatic gene expression in newborns was interpreted in light of the observed biological responses and gene expression changes arising in the lungs of dams following CB exposure. Although retention of CB particles was observed in dams from both the medium and the high dose groups, neutrophil-marked inflammation and altered expression of several cytokines and chemokines, both at the transcriptional and tissue protein levels, was significant only in the high dose group. Analysis of newborn livers by DNA microarrays revealed that female offspring were more sensitive to maternal exposure than male offspring. Cellular signalling, inflammation, cell cycle and lipid metabolism were among the biological pathways affected in female offspring. Males, however, responded with subtle changes in metabolism-related genes. Further investigation is required to determine the long-term health consequences of the gene expression changes in offspring and response to environmental stresses., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

The induction of inherited DNA sequence mutations arising in the germline (i.e., sperm or egg) of mice exposed in utero to diesel exhaust particles (DEPs) via maternal inhalation compared to unexposed controls was investigated in this study. Previous work has shown that particulate air pollutants (PAPs) from industrial environments cause DNA damage and mutations in the sperm of adult male mice. Effects on the female and male germline during critical stages of development (in utero) are unknown. In mice, previous studies have shown that expanded simple tandem repeat (ESTR) loci exhibit high rates of spontaneous mutation, making this endpoint a valuable tool for studying inherited mutation and genomic instability. In the present study, pregnant C57Bl/6 mice were exposed to 19mg/m(3) DEP from gestational day 7 through 19, alongside air exposed controls. Male and female F1 offspring were raised to maturity and mated with control CBA mice. The F2 descendents were collected and ESTR germline mutation rates were derived from full pedigrees (mother, father, offspring) of F1 male and female mice. We found no evidence for increased ESTR mutation rates in females exposed in utero to DEP relative to control females. In contrast, a statistically significant increase in the mutation frequency of male mice exposed in utero to DEP was observed (2-fold; Fisher's exact p<0.05). Thus, maternal exposure to DEP results in increased mutation in sperm during development., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

Genetic alterations underlying the development of the cancer of the nose and paranasal sinuses (sinonasal cancer, SNC), a rare cancer that can be included in the group of head and neck cancers, are still largely unknown. We recently reported that TP53 mutations are a common feature of SNC, with an overall frequency of 77%, and they show association to adenocarcinoma and wood-dust exposure [15]. In this study, we report in detail the sequence change for 159 TP53 mutations identified by direct sequencing. More than half of the mutations (60%, 95/159) were missense mutations; there were also 28 (18%) frameshift or nonsense mutations, and 36 (23%) intronic or silent mutations. In coding region, the most common base change detected was C-->T transition (43/125; 34% of base changes in the coding region). G-->T transversions occurred at a frequency of 10% (12/125), which is less than reported in mutation databases for head and neck squamous cell carcinoma (24%). Characteristically, in our SNC series, the mutations were scattered over a large number of codons, codon 248 being the most frequent target of base substitution. Codon 135 was the second most frequently mutated codon; this nucleotide position has not been reported before as frequently mutated in head and neck cancer or human cancer in general. About half of all tumours with TP53 mutations carried more than one mutation. Interestingly, 86% (19/22) of the silent mutations detected had occurred in tumours with multiple mutations., (Copyright 2009 Elsevier B.V. All rights reserved.)

The particulate phase of diesel engine exhaust is likely carcinogenic. However, the mechanisms of diesel exhaust particles (DEPs) induced mutagenicity/carcinogenicity are still largely unknown. We determined the mutant frequency following eight repeated 72 h incubations with 37.5 or 75 microg/ml DEP (NIST SRM 1650) in the FE1-MutaMouse lung epithelial cell line. We measured DEP-induced acellular and intracellular production of reactive oxygen species (ROS) and compared with ROS production induced by carbon black, which we have previously shown is mutagenic in this cell line [N.R. Jacobsen, A.T. Saber, P. White, P. Moller, G. Pojana, U. Vogel, S. Loft, J. Gingerich, L. Soper, G.R. Douglas, H. Wallin. Increased mutant frequency by carbon black, but not quartz, in the lacZ and cII transgenes of mutamouse lung epithelial cells, Environ. Mol. Mutagen. 48(6) (2007) 451-461]. The mutant frequency was marginally elevated in cells treated with 37.5 microg/ml DEP (1.29-fold [95% CI: 0.96-1.60], p=0.08) and significantly increased in cells treated with 75 microg/ml DEP (1.55-fold [95% CI: 1.23-1.87], p < 0.001). ROS production from DEP was low both within cells and in acellular systems when compared to carbon black. These results show that DEP are mutagenic in a mammalian cell line in vitro and that additional pathways besides ROS production, such as those involving the presence of polycyclic aromatic hydrocarbons, likely are involved in the mutagenesis.

Lung cancer risk was investigated in relation to single nucleotide polymorphisms in genes involved in the inflammatory response. The aim was to see if polymorphisms modifying the inflammatory response are associated with risk of lung cancer and if there were interactions between the same polymorphism and factors, which modify an inflammatory response, such as smoking status, duration, and intensity, and use of NSAID. The functional SNPs IL-1B T-31C, IL6 G-174C, IL8 T-251A, IL10 C-592T, COX2 C8473T, COX2 A-1195G and PPARgamma2 Pro(12)Ala were included. A case-cohort study including 428 lung cancer cases and a sub-cohort of 800 persons was nested within a population-based prospective study of 57,053 individuals. Variant allele carriers of IL-1B T-31C were at increased risk of lung cancer (IRR=1.51, 95% CI=1.08-2.12). There was interaction between the polymorphism COX-2 T8473C and smoking status. Thus, non-smoking variant allele carriers were at 5.75-fold (95% CI=1.25-26.43) higher risk of lung cancer than for homozygous wild type allele carriers. Lung cancer risk was similar for all genotype carriers among past and current smokers. There were, however, very few non-smoking lung cancer cases. There was interaction between IL-1B T-31C, COX-2 A-1195G and PPARgamma2 Pro(12)Ala and NSAID use in relation to lung cancer risk. For the two latter, NSAID use was only associated with a lower cancer risk among homozygous wild type allele carriers. p for interaction was 3 x 10(-6) for COX-2 A-1195G and 9 x 10(-5) for PPARgamma2 Pro(12)Ala. The results suggest that NSAID use may modify risk of lung cancer differently depending on the genotype.

The gastrointestinal route of exposure to particulate matter is important because particles are ingested via contaminated foods and inhaled particles are swallowed when removed from the airways by the mucociliary clearance system. We investigated the effect of an intragastric administration by oral gavage of diesel exhaust particles (DEP) in terms of DNA damage, oxidative stress and DNA repair in colon epithelial cells, liver, and lung of rats. Eight rats per group were exposed to Standard Reference Material 2975 at 0.064 or 0.64 mg/kg bodyweight for 6 and 24 h. Increased levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine lesions were observed at the highest dose after 6 and 24 h in all three organs. 8-Oxo-7,8-dihydro-2'-deoxyguanosine is repaired by oxoguanine DNA glycosylase 1 (OGG1); upregulation of this repair system was observed as elevated pulmonary OGG1 mRNA levels after 24 h at both doses of DEP, but not in the colon and liver. A general response of the antioxidant defence system is further indicated by elevated levels of heme oxygenase 1 mRNA in the liver and lung 24 h after administration. The level of bulky DNA adducts was increased in liver and lung at both doses after 6 and 24h (DNA adducts in colon epithelium were not investigated). In summary, DEP administered via the gastrointestinal tract at low doses relative to ambient exposure generates DNA damage and increase the expression of defence mechanisms in organs such as the lung and liver. The oral exposure route should be taken into account in risk assessment of particulate matter.

Inflammatory bowl disease predisposes to cancer of the colorectum, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) decreases the risk; hence genetic variations that modify the inflammatory response may alter the risk of colorectal cancer (CRC). The purpose of this study was to determine if polymorphisms associated with an altered inflammatory response are associated with colorectal cancer risk, and to investigate the possible interaction with lifestyle factors such as alcohol use, smoking and NSAID use. We studied 355 adenocarcinoma cases and 753 control persons, nested within the prospective "Diet, Cancer and Health" study. None of the polymorphisms were associated with risk of colorectal cancer. A statistically significant interaction between PPARgamma2 Pro(12)Ala and alcohol was found, where alcohol use was associated with a 22% increased risk of CRC per 10g alcohol/day among carriers of the variant allele but not among homozygous wild type allele carriers (P for interaction=0.02). Moreover, an interaction between DLG5 R30Q and NSAID use was found (P for interaction=0.02). Our results do not suggest that inborn variations in the inflammatory response play any major role in risk of colorectal cancer.

Airborne particulate matter (PM) was sampled by use of an electrostatic sampler in an oven hall and a receiving hall in a waste-incineration energy plant, and from urban air in a heavy-traffic street and from background air in Copenhagen. PM was sampled for 1-2 weeks, four samples at each site. The samples were extracted and examined for mutagenicity in Salmonella typhimurium strains TA98, YG1041 and YG5161, for content of inorganic elements and for the presence of eight polycyclic aromatic hydrocarbons. The induction of IL-6 and IL-8 mRNA expression and the presence of DNA damage - tested by the comet assay - were determined after 24-h incubations with human A549 lung epithelial cells. The PM(2.5) concentration was about twofold greater in the oven hall than in the receiving hall. The particle size distribution in the receiving hall was similar to that in street air (maximum mode at about 25nm), but the distribution was completely different in the oven hall (maximum mode at about 150nm). Also chemically, the samples from the oven hall were highly different from the other samples. PM extracts from the receiving hall, street and background air were more mutagenic than the PM extracts from the oven hall. PM from all four sites caused similar levels of DNA damage in A549 cells; only the oven hall samples gave results that were statistically significantly different from those obtained with street-air samples. The receiving hall and the urban air samples were similarly inflammatory (relative IL-8 mRNA expression), whereas the oven hall did not cause a statistically significant increase in IL-8 mRNA expression. A principal component analysis separated the oven hall and the receiving hall by the first principal component. These two sites were separated from street and background air with the second principal component. Several clusters of constituents were identified. One cluster consisted of all the polycyclic aromatic hydrocarbons (PAH), several groups of metals and one group of the biological endpoints (DNA damage, IL-6 and IL-8 mRNA expression). The PAH and the inorganic content of the air in the receiving hall may be due to vehicle emissions and suspended waste particles. The inorganic content in the street and background air may have been influenced by break wear, road emissions and long-range transport. The results from a partial least-square regression analysis predicted that both PAHs and a group of metals including Fe and Mn contributed to IL-6 and IL-8 induction. Only Mn and Sr were predicted to influence DNA damage statistically significantly. Among the PAHs only chrysene had influence on DNA damage. The PM from the oven hall was markedly different from the PM at other locations in particle size distribution, chemical composition and the resulting biological effects when A549 cells were incubated with the PM. These characteristics and observations in the oven hall indicated that the PM source was oven exhaust, which was well combusted.

Exposure to wood dust is common in many workplaces. Epidemiological studies indicate that occupational exposure to hardwood dusts is more harmful than to softwood dusts. In this study, human epithelial cell line A549 was incubated with well-characterized dusts from six commonly used wood species and from medium density fibreboard (MDF), at concentrations between 10 and 300microg/ml. After 3 and 6h of incubation, genotoxicity was assessed by measurement of DNA damage with the single-cell gel electrophoresis (comet) assay and inflammation was measured by the expression of IL-6 and IL-8 mRNA and by the amount of IL-8 protein. There was a 1.2-1.4-fold increase in DNA strand breaks after incubation with beech, teak, pine and MDF dusts compared with the levels in untreated cells, but after 6h only the increase induced by the MDF dust remained. Increased expression of cellular IL-6 and IL-8 mRNA was induced by all of the wood dusts at both times. Similar to IL-8 mRNA expression, the amounts of secreted IL-8 protein were elevated, except after incubation with oak dust, where a marginal reduction was seen. On the basis of the effects on IL-8 mRNA expression, the wood dusts could be divided into three groups, with teak dust being the most potent, MDF, birch, spruce and pine being intermediate, and beech and oak being the least potent. The induction of DNA strand breaks did not correlate well with the interleukin response. In conclusion, all wood dusts induced cytokine responses, and some dusts induced detectable DNA damage. The inflammatory potency seemed intermediate for dusts from the typical softwoods spruce and pine, whereas the dusts from species linked to cancer, beech and oak, were the least inflammatory. The variation of the effects induced by different wood dusts over time indicates that the DNA damage was not secondary to the cytokine response. Although hardwoods are often considered more harmful than softwoods by regulatory agencies, the current experiments do not provide evidence for a clear-cut distinction between toxicities of hardwood and softwood dust.

Polymorphisms in the XPD and the XPC gene have been associated with a lower DNA repair capacity. We determined the risk of colorectal cancer in association with the four polymorphisms XPA A23G, XPC Lys939Gln, XPD Lys751Gln and XPD Asp312Asn, and interactions between the polymorphisms and the environmental factors: smoking intensity, intake of alcohol, red meat, processed meat, fish and poultry, fruits and vegetables and dietary fibres, in relation to development of colorectal cancer in a study population of 405 colorectal cancer cases and a comparison group of 810 persons, nested within the Danish prospective cohort, Diet, Cancer and Health, of 57053 cohort members. No association was found between the XPC Lys939Gln, XPA A23G, XPD Lys751Gln, and XPD Asp312Asn polymorphisms and risk of colorectal cancer. The association of the XPD Lys751Gln polymorphism was statistically significantly different between genders, with a lower risk of colorectal cancer among women carrying the variant allele. We observed a statistically significant interaction between the XPC Lys939Gln polymorphism and consumption of red meat, with a 3.7-fold increase in colorectal cancer risk per 100g red meat intake per day among carriers of the homozygous variant, but virtually no effect of red meat intake among carriers of the wild type allele. In the light of the multiple comparisons being made, this result may be a chance finding. The results showed no interaction between the XPD Lys751Gln, XPA A23G, and XPD Asp312Asn polymorphisms and the environmental factors for the development of colorectal cancer. Overall, the results of the present study indicate that the four polymorphisms are not of major importance in colorectal cancer carcinogenesis.

We investigated the risk of basal cell carcinoma (BCC) in relation to a number of single nucleotide polymorphisms in genes involved in the inflammatory response. A case-control study including 322 BCC cases and a similar number of controls was nested in a population-based prospective study of 57,053 individuals (aged 50-64 at inclusion) in Denmark. NSAID use was associated with a slightly decreased risk of BCC (IRR=0.85, 95% CI=0.66-1.10). We found that two polymorphisms in COX-2, COX-2 A-1195G and T8473C were associated with risk of BCC. Carriers of the variant allele of COX-2 A-1195G had lower risk of BCC than homozygous wild type carriers (IRR=0.54, 95% CI=0.47-0.89). Homozygous carriers of the variant allele of COX-2 T8473C were at 2.27-fold higher risk of BCC (95% CI=1.31-3.92) than homozygous wild type allele carriers. The polymorphisms IL6 G-174C, IL8 T-251A, PPARgamma2 Pro(12)Ala, IL1beta T-31C, and IL10 C-592A were not associated with risk of BCC. We found no statistically significant interaction between polymorphisms and NSAID use in relation to risk of BCC. While it cannot be ruled out that the present findings are due to chance, the results indicate that high COX-2 expression may increase risk of BCC while NSAID use may be protective.

Low DNA-repair capacity has been associated with increased risk of several types of cancer. mRNA levels of the nucleotide excision repair genes ERCC1 and XPD have been shown to correlate with the DNA-repair capacity. Likewise, mRNA levels of several DNA-repair genes including ERCC1 have been shown to be lower in lymphocytes from patients with lung cancer and head and neck cancer compared with healthy persons. In these studies, the low DNA-repair gene expression levels could be either a risk factor for disease or a consequence of the same. In this nested case-cohort study, which to our knowledge, is the first prospective study of DNA-repair gene mRNA levels as predictors of lung cancer, we have investigated the occurrence of lung cancer in relation to the mRNA level of the two DNA-repair genes ERCC1 and XPD and the NF kappaB inhibitor RAI in blood samples prior to disease. Among 54,220 members of a Danish prospective cohort study, 265 lung cancer cases were identified and a sub-cohort comprising 272 individuals was used for comparison. The expression levels of the three adjacent genes were found to be highly inter-correlated, to be higher in women compared to men and to be lower in older individuals. The incidence rate ratios for lung cancer in association with one log-unit increase (natural logarithm) in mRNA levels were 1.12 (CI=0.89-1.41) for ERCC1, 1.00 (CI=0.83-1.21) for XPD and 1.25 (0.89-1.74) for RAI. In conclusion, this study indicated no association between mRNA expression of the DNA-repair genes ERCC1 and XPD and risk of subsequent development of lung cancer.

Sucrose-rich diets have repeatedly been observed to have co-carcinogenic actions in colon and liver of rats and to increase the number of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) induced aberrant crypt foci in rat colon. To investigate a possible interaction between sucrose and IQ on the genotoxicity in rat liver and colon, we gave Big Blue rats a diet containing sucrose (0%, 3.45% or 13.4% w/w) and/or IQ (70 ppm) for a period of 3 weeks. Sucrose and IQ increased the mutation frequency in the colon. The effect of combined treatments with IQ and sucrose on the mutation frequencies was additive indicating that sucrose and IQ act independently. This was supported by the mutation spectra where sucrose expands the background mutations in the colon, whereas IQ, in other studies, more specifically has induced G:C --> T:A transversions. In the liver IQ increased the mutation frequency, whereas addition of sucrose reduced the effect of IQ in a dose-dependent manner. The level of bulky DNA adducts in liver and colon was increased in animals exposed to either sucrose or IQ. In animals exposed to IQ, addition of sucrose had marginal effects on the level of bulky DNA adducts. Markers of oxidative damage and DNA repair were generally unaffected by the treatments. In conclusion, sucrose and IQ in the diet induced mutations in the colon by independent mechanisms, whereas an interaction was observed in liver leading to a decrease in mutations by the combined treatment.

Recent studies have identified an indirect genotoxicity pathway involving inflammation as one of the mechanisms underlying the carcinogenic effects of air pollution/diesel exhaust particles (DEP). We investigated the short-term effects of DEP on markers of inflammation and genotoxicity in vitro and in vivo. DEP induced an increase in the mRNA level of pro-inflammatory cytokines and a higher level of DNA strand breaks in the human lung epithelial cell line A549 in vitro. For the in vivo study, mice were exposed by inhalation to 20 or 80 mg/m3 DEP either as a single 90-min exposure or as four repeated 90-min exposures (5 or 20 mg/m3) and the effects in broncho-alveolar lavage (BAL) cells and/or lung tissue were characterized. Inhalation of DEP induced a dose-dependent inflammatory response with infiltration of macrophages and neutrophils and elevated gene expression of IL-6 in the lungs of mice. The inflammatory response was accompanied by DNA strand breaks in BAL cells and oxidative DNA damage and increased levels of bulky DNA adducts in lung tissue, the latter indicative of direct genotoxicity. The effect of a large single dose of DEP was more pronounced and sustained on IL-6 expression and oxidative DNA damage in the lung tissue than the effect of the same dose administered over four days, whereas the reverse pattern was seen in BAL cells. Our results suggest that the effects of DEP depend on the rate of delivery of the particle dose. The mutation frequency (MF), after DEP exposure, was determined using the transgenic Muta Mouse and a similar exposure regimen. No increase was observed in MF in lung tissue 28-days after exposure. In conclusion, short-term exposure to DEP resulted in DNA strand breaks in BAL cells, oxidative DNA damage and DNA adducts in lungs; and suggested that DNA damage in part is a consequence of inflammatory processes. The response was not associated with increased MF, indicating that the host defence mechanisms were sufficient to counteract the adverse effects of inflammation. Thus, there may be thresholds for the inflammation-associated genotoxic effects of DEP inhalation.

Several chemical mutagens and carcinogens, including polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs, are adsorbed to the surface of diesel exhaust particles (DEP). DEP can induce formation of reactive oxygen species and cause oxidative DNA damage as well as bulky carcinogen DNA adducts. Lung tissue is a target organ for DEP induced cancer following inhalation. Recent studies have provided evidence that the lung is also a target organ for DNA damage and cancer after oral exposure to other complex mixtures of PAHs. The genotoxic effect of oral administration of DEP was investigated, in terms of markers of DNA damage, mutations and repair, in the lung of Big Blue rats fed a diet with 0, 0.2, 0.8, 2, 8, 20 or 80 mg DEP/kg feed for 21 days. There was no significant increase in the mutation frequency in the cII gene. However, an increase of DNA damage measured as DNA strand breaks (comet assay) and bulky DNA adducts (32P post labeling) was observed. The level of DNA strand breaks increased significantly at all dose levels while the level of DNA adducts increased significantly only at the intermediate dose levels. Similarly, the number of oxidized DNA bases measured as endonuclease III and fapyguanine glycosylase (FPG) sensitive sites increased at the intermediate dose levels. The induction of DNA damage by DEP exposure did not increase the expression of the repair genes OGG1 and ERCC1 at the mRNA level. The present study indicates that the lung is a target organ for primary DNA damage following oral exposure to DEP. DNA damage was induced following exposure to relatively low levels of DEP, but under the conditions used in the present experiment DNA damage did not result in an increased mutation rate.

Lung cancer is the most common fatal cancer among Danish men, and the incidence rate is increasing among women. In a case-cohort study, we have investigated the occurrence of lung cancer in relation to a high-risk haplotype, previously identified for breast cancer among post-menopausal women, and in relation to the closely linked polymorphisms XPD Asp312Asn and Lys751Gln. Among 54220 members of a Danish prospective cohort study aged 50-64 at entry, 265 lung cancer cases were identified and a sub-cohort comprising 272 individuals was used for comparison. Among women in the 50-55 year age interval, homozygous carriers of the high-risk haplotype were at increased risk of lung cancer (RR=7.02, 95% CI=1.88-26.18). In the 56-60 year and 61-70 year age intervals, no associations were observed. Among men, no statistically significant associations were found in any age interval. Female homozygous carriers of the variant allele of XPD Lys751Gln were at significantly increased risk of lung cancer in the two younger age-intervals (50-55 years: RR=5.60, 95% CI=1.18-26.45, 56-60 years: RR=10.60, 95% CI=1.50-75.64). Among men, carriers of the variant allele of XPD Lys751Gln had a non-significantly increased risk of lung cancer in the youngest age interval (RR=6.38, 95% CI=0.74-54.90). When the polymorphisms in XPD Asp312Asn and Lys751Gln were mutually adjusted, XPD Asp312Asn was not associated with increased risk of cancer. We found no interaction between genotypes and duration of smoking. In conclusion, two regions of chromosome 19q13.2-3 seem to be associated with risk of lung cancer.

Background: Previous studies in Denmark have shown that bus drivers and tramway employees were at an increased risk for developing several types of cancer and that bus drives from central Copenhagen have high levels of biomarkers of DNA damage., Aims: The present study evaluates 1-hydroxypyrene concentrations and mutagenic activity in urine as biomarkers of exposure in non-smoking bus drivers in city and rural areas on a work day and a day off and in non-smoking mail carriers working outdoors (in the streets) and indoors (in the office)., Methods: Twenty-four hour urine samples were collected on a working day and a day off from 60 non-smoking bus drivers in city and rural areas and from 88 non-smoking mail carriers working outdoors (in the streets) and indoors (in the office). The concentration of 1-hydroxypyrene was measured by means of HPLC and the mutagenic activity was assessed by the Ames assay with Salmonella tester strain YG1021 and S9 mix. The N-acetyltransferase (NAT2) phenotype was used as a biomarker for susceptibility to mutagenic/carcinogenic compounds., Results: Bus drivers excreted more 1-hydroxypyrene in urine than did mail carriers. The differences were slightly smaller when NAT2 phenotype, cooking at home, exposure to vehicle exhaust, and performing physical exercise after work were included. The NAT2 slow acetylators had 29% (1.29 [CI: 1.15-1.98]) higher 1-hydroxypyrene concentrations in urine than the fast acetylators. Male bus drivers had 0.92 revertants/mol creatinine [CI: 0.37-1.47] and female bus drivers 1.90 revertants/mol creatinine [CI: 1.01-2.79] higher mutagenic activity in urine than mail carriers., Conclusion: The present study indicates that bus drivers are more exposed to polycyclic aromatic hydrocarbons (PAH) and mutagens than mail carriers. Mail carriers who worked outdoors had higher urinary concentration of 1-hydroxypyrene, a marker of exposure to PAH, than those working indoors. The individual levels of urinary mutagenic activity were not correlated to excretion of 1-hydroxypyrene. This might be due to the fact that the most potent mutagenic compounds in diesel exhaust are not PAH but dinitro-pyrenes. Among bus drivers, fast NAT2 acetylators had higher mutagenic activity in urine than slow NAT2 acetylators and female bus drivers had higher mutagenic activity than male bus drivers.

Earlier studies have indicated that sucrose increases 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced aberrant crypt foci in the colon. In this study, we investigated the role of sucrose in IQ-induced genotoxicity of the colon mucosa and liver. Big Blue rats were fed with IQ (20 ppm in feed) and/or sucrose (3.45 or 6.85 wt.% in feed) for 3 weeks. IQ increased DNA strand breaks in the colon, whereas the mutation frequency was increased in the liver. The level of IQ-induced DNA adducts was elevated in both colon mucosa cells and liver. In the liver, high sucrose intake increased the level of DNA adducts above that of IQ and low sucrose intake. Oxidative DNA damage detected in terms of 7-hydro-8-oxo-2'-deoxyguanosine by HPLC-EC, or endonuclease III or formamidopyrimidine DNA glycosylase sensitive sites were unaltered in the colon and liver. Expression of ERCC1 and OGG1 mRNA levels were unaffected by IQ or sucrose feeding. Biomarkers of oxidative stress, including Vitamin C, malondialdehyde and protein oxidations (gamma-glutamyl semialdehyde and 2-amino adipic semialdehyde) were unaltered in plasma and in liver. In conclusion, sucrose feeding increases IQ-induced genotoxicity in liver but not in colon, suggesting different mechanisms for sucrose and IQ in colon mutagenesis.

Ozone (O3) is a well-known oxidant pollutant present in photochemical smog. Although ozone is suspected to be a respiratory carcinogen it is not regulated as a carcinogen in most countries. The genotoxic and inflammatory effects of ozone were investigated in female mice exposed to ozone for 90 min. The tail moment in bronchoalveolar lavage (BAL) cells from BALB/c mice was determined by the comet assay as a measure of DNA strand breaks. Within the first 200 min after exposure, the BAL cells from the mice exposed to 1 or 2 ppm ozone had 1.6- and 2.6-fold greater tail moments than unexposed mice. After 200 min there was no effect. It could be ruled out that the effect during the first 200 min was due to major infiltration of lymphocytes or neutrophils. Unexpectedly, ozone had no effect on the content of 8-oxo-deoxyguanosine (8-oxo-dG) in nuclear DNA or on oxidised amino acids in the lung tissue. The mRNA level of the repair enzyme ERCC1 was not increased in the lung tissue. Inflammation was measured by the cytokine mRNA level in lung homogenates. An up to 150-fold induction of interleukin-6 (IL-6) mRNA was detected in the animals exposed to 2 ppm ozone compared to the air-exposed control mice. Also at 1 ppm ozone, the IL-6 mRNA was induced. The large induction of IL-6 mRNA in the lung took place after DNA strand breaks were induced in BAL. This does not support the notion that inflammatory reactions are the cause of DNA damage. To determine whether these exposures were mutagenic, Muta Mice were exposed to 2 ppm ozone, 90 min per day for 5 days. No treatment-related mutations could be detected in the cII transgene. These results indicate that a short episode of ozone exposure at five times the threshold limit value (TLV) in US induces lung inflammatory mediators and DNA damage in the cells in the lumen of the lung. This was not reflected by an induction of mutations in the lung of Muta Mice.

The dorsal skin of C3H/Tif/hr hairless mice was painted with coal tar, pharmacological grade. Epidermal cells and hepatocytes were isolated after 4, 24, 48 and 96 h and DNA strand breaks were determined as tail moment by the alkaline comet assay. The tail moment of epidermal cells was significantly greater at the time points 4, 24, 48 and 96 h after exposure compared to the controls, with the most DNA strand breaks at 24 h. The DNA strand breaks in epidermal cells increased linearly with the dose of coal tar. In hepatocytes, no difference in DNA strand breaks was found between exposed animals and controls. DNA adducts were determined by the 32P-postlabeling assay. For epidermal cells, the mean DNA adduct level was 12-fold greater in coal tar painted mice after 24 h than in controls. Again, a linear dose/response relationship was seen 24 h after painting. For liver DNA, the mean DNA adduct level was 3-fold greater than for controls. The mutation frequency in epidermal and liver cells was examined in lambdalacZ transgenic mice (MutaMouse). Thirty-two days after painting, the mutation frequency in epidermal cells was 16-fold greater in coal tar treated mice compared to controls. No effect was detected in hepatocytes. We found that a single painting of coal tar resulted in strong genotoxic effects in the murine epidermis, evidenced by induction of DNA strand breaks and DNA adducts in hairless mice and lambdalacZ mutations in the MutaMouse. This demonstrates that it is possible to detect genotoxic effects of mixtures with high sensitivity in mouse skin by these end-points.

Azo pigments are used extensively as coloring agents in inks, paints and cosmetics. We have surveyed the literature for genotoxic and cancer data on nine colorants, which are structurally related to 1-phenylazo-2-hydroxynaphthalene (C.I. Solvent yellow 14). C.I. Solvent yellow 14 is metabolized by oxidative and peroxidative enzymes. Metabolically activated C.I. Solvent yellow 14 forms both RNA and DNA adducts. It induces liver nodules in rats upon oral administration. Although there is a mixture of negative and positive findings in short-term tests and in animal cancer studies, C.I. Solvent yellow 14 should be considered genotoxic. C.I. Pigment red 3 should be considered carcinogenic but is only weakly genotoxic. C.I. Solvent yellow 7, C.I. Pigment orange 5, C.I. Pigment red 4, and C.I. Pigment red 23 should be considered genotoxic. C.I. Pigment red 53:1 is not genotoxic, and observations of spleen tumors in male rats but not in female rats or mice seem to be related to toxic effects of high doses of C.I. Pigment red 53:1 in this organ. The data in the literature indicate that Pigment red 57:1 is not genotoxic or carcinogenic. We did not find sufficient data for a relevant evaluation of C.I. Pigment red 2 and C.I. Pigment red 64:1. Some of the colorants have in common the 2-amino-1-naphthol structure. This compound is not genotoxic. On the other hand, reductive cleavage of the azo bonds or hydrolysis of anilido bonds would produce aromatic amines, most of which have been under suspicion for genotoxicity or carcinogenicity. For C.I. Pigment red 53:1 and 57:1, sulphonated aromatic amines would be formed that are not genotoxic.

We have studied DNA repair in patients with psoriasis aiming at investigating the importance of repair in chemically induced cancer. An increased risk of non-melanoma skin cancer has been observed in psoriasis patients extensively treated with tar, methotrexate and photochemotherapy (psoralen + UVA). We measured the DNA repair capacity (DRC) by a host cell reactivation (HCR) assay in lymphocytes from psoriasis patients with and without basal cell cancer and non-psoriatic persons with and without basal cell cancer (4 x 20 study persons). Among psoriasis patients we observed a significant lower DRC in patients with skin cancer compared to patients without skin cancer (P = 0.015; Mann-Whitney, one-sided). Using the median of the healthy control group (group 4) as a cutoff value to divide the psoriasis patients into groups of high and low repair, we found that individuals who had a low repair capacity had a 6.4-fold increased skin cancer risk compared to individuals with high repair (95% confidence interval (CI), 1.44-28.5). The level of DNA repair was correlated with the age at which the psoriasis patients got their first skin cancer. The lower the level of DNA repair, the earlier the psoriasis patients had their first skin tumor (P = 0.070 Spearman; one-sided). Psoriasis patients without BCC had marginally higher repair than healthy controls (P = 0.11, Mann-Whitney, two-sided). We found no difference between BCC patients without psoriasis and healthy controls. In conclusion, these findings suggest a protective role of DNA repair in a predominantly chemically induced cancer.

Reactive oxygen species are formed constantly in living organisms, as products of the normal metabolism, or as a result of many different environmental influences. Here we review the knowledge of formation of DNA damage, the mutations caused by reactive oxygen species and the role of the excision repair processes, that protect the organism from oxidative DNA damage. In particular, we have focused on recent studies that demonstrate the important role of nucleotide excision repair. We propose two major roles of nucleotide excision repair as 1) a backup when base excision repair of small oxidative lesions becomes saturated, and as 2) a primary repair pathway for DNA damage produced by lipid peroxidation products., (Copyright 1998 Elsevier Science B.V. All rights reserved.)

Quadruples of skin cancer patients with and without psoriasis and referents with and without psoriasis (4 x 20 study persons) were identified and examined for DNA damage by single cell gel electrophoresis (comet-assay) and DNA-repair by UV-induced unscheduled DNA synthesis (UDS) in mononuclear blood cells (lymphocytes and monocytes). DNA damage (strand breaks and alkaline labile sites) as assessed by the comet assay and DNA repair as assessed by UDS were significantly associated with the season in which blood sampling took place. This variation might be explained by an increased exposure to solar radiation. When the comet tail moment data were stratified by sampling period, an interaction between psoriasis and skin cancer was detected, with patients with psoriasis and skin cancer exhibiting more DNA damage. Patients with psoriasis and skin cancer also had lower UDS compared to healthy study persons, suggesting that the more DNA damage may be caused by a lower rate of DNA repair. In all study persons, the extent of UDS correlated positively with the amount of DNA damage determined by the comet assay.