Micronuclei induced by airborne particulate matter from Mexico City

In vitro evaluation of the cytotoxicity, mutagenicity and DNA damage induced by particle matter and gaseous emissions from a medium-duty diesel vehicle under real driving conditions using palm oil biodiesel blends

The influence of palm oil biodiesel content on the cytotoxicity, mutagenicity and genotoxicity of particle- and gas-phase diesel vehicle emissions was investigated. The emissions were collected on-board of a EURO IV diesel truck, fuelled with mixtures of 10% (B10), 20% (B20) and 100% (B100) of palm oil biodiesel, under real driving conditions. Organic extracts of the particulate matter (PM) and gases were characterised for 17 PAH (including EPA priority) and used for the biological assay. Increasing biodiesel content in the fuel mixture results in a decrease in the PM and PAH emission factors, both in the particulate and gas-phase. The majority of the PAH are present in the gas-phase. The mutagenic potencies, in TA98 bacteria, are higher for B20 in both phases, whereas the mutagenicity emission factor, that takes into account the lower emission of PM and PAH, is not significantly different between the fuels. Higher direct mutagenicity (TA98 + S9) is observed in all the tested fuels, indicating the action of carcinogenic compounds other than non-substituted PAH. The gas-phase extracts present higher cytotoxicity and genotoxicity in lung epithelial cell A549, which may be related to the higher PAH content in the gas-phase. The increase in biodiesel content have a different impact on cytotoxicity, being larger in the gas-phase and lower in the particle-phase. This indicates that pulmonary toxicity may be higher for the gaseous emissions, due to the role of different toxic compounds compared to the PM. The adverse biological effects when biodiesel content increases are not consequent with the reduction of the PAH characterised, indicating that other toxic compounds are more relevant. Further investigations to identify these compounds are required in order to update and focus the efforts regarding emission targets and controls.

Monitoring human genotoxicity risk associated to urban and industrial Buenos Aires air pollution exposure

The quality of life in large megacities is directly affected by its air quality. In urban environments, suspended particles from anthropogenic origin is one of the main air contaminants identified as highly genotoxic, mutagenic, or carcinogenic. Atmospheric monitoring is therefore imperative, and bioassays to detect the effects of genotoxic agents give usually excellent results. Analysis of micronucleus (MN) in exfoliated oral mucosa cells is a sensitive non-invasive method for monitoring genetic damage in human populations. The first aim of this study was to analyze and characterize levels of volatile organic compounds (VOCs), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) in two areas from Buenos Aires: La Plata city, an urban (U) area and Ensenada, an industrial (I) area. Secondly, we evaluated the possible health risk of its inhabitants through a simple genotoxic assay on exfoliated oral mucosa cells. Whole blood cell count and nuclear abnormalities frequencies were evaluated in the exfoliated oral mucosa cells from urban and industrial inhabitants. Smoking habit represented a significant factor increasing MN percentage while, age did not increase the production of any of the nuclear aberrations assayed (micronuclei, binucleated, karyorrhexis) when the inhabitants from the urban and the industrial areas were compared. In addition, changes in MN and binucleated cell percentages in males and females were found to be area-dependent. We suggest that regardless PM concentration, PM-specific characteristics (size, shape, chemical elements, etc.) and VOCs levels could be responsible for the different harmful genotoxic effects seen in the two areas. Although this is a preliminary study, our results allowed to recognize that individuals living in both the urban and the industrial areas could be considered susceptible groups and should periodically undergo biological monitoring and appropriate care.

Correlation of α/γ-Fe2O3 nanoparticles with the toxicity of particulate matter originating from subway tunnels in Seoul stations, Korea

According to the increasing concern about particulate matter (PM) pollution at subway systems, particularly its potentially severe effects on human health, this study investigated the constituents, characteristics, and toxicity of PM collected at underground subway stations in Seoul, Korea. It was found that α/γ-Fe₂O₃ NPs, which are considered as thermal products derived from the brake-wheel-rail interface, were the main components of PM (57.6% and 48% of PM₁₀ and PM_2.5, respectively). In addition, hydrothermally synthesized α/γ-Fe₂O₃ NPs, proposing to possess similar properties to those of Fe₂O₃ contained in PM, were used to investigate the correlation of these oxides with PM toxicity. In particular, the synthesized γ-Fe₂O₃ NPs induced a negligibly toxic, while the synthesized α-Fe₂O₃ NPs and PM showed remarkably toxic effects on HeLa cells and zebrafish embryos, specifically in reducing cell proliferation to 85% and 72% survival, causing high apoptosis of 29.8% and 29.3%, and inhibiting the development of embryos up to 60% and 8% after prolonged exposure, respectively. It is considered that α-Fe₂O₃ NPs were primarily responsible for the harmful effects of PM, resulting in significant damage to DNA due to their capacity of producing high reactive oxygen species (ROS) and, thus, deleterious effects on the human body.

Distribution of PM2.5 Air Pollution in Mexico City: Spatial Analysis with Land-Use Regression Model

In this study, the spatial distribution of PM2.5 air pollution in Mexico City from 37 personal exposures was modeled. Meteorological, demographic, geographic, and social data were also included. Geographic information systems (GIS), spatial analysis, and Land-Use Regression (LUR) were used to generate the final predictive model and the spatial distribution map which revealed two areas with very high concentrations (up to 109.3 µg/m3) and two more with lower concentrations (between 72 to 86.5 µg/m3) (p < 0.05). These results illustrate an overview trend of PM2.5 in relation to human activity during the studied periods in Mexico City and show a general approach to understanding the spatial variability of PM2.5.

Prenatal exposure to particulate matter and ozone: Bulky DNA adducts, plasma isoprostanes, allele risk variants, and neonate susceptibility in the Mexico City Metropolitan Area

Mexico City's Metropolitan Area (MCMA) includes Mexico City and 60 municipalities of the neighbor states. Inhabitants are exposed to emissions from over five million vehicles and stationary sources of air pollutants such as particulate matter (PM) and ozone. MCMA PM contains elemental carbon and organic carbon (OC). OCs include polycyclic aromatic hydrocarbons (PAHs), many of which induce mutagenic and carcinogenic DNA adducts. Gestational exposure to air pollution has been associated with increased risk of intrauterine growth restriction, preterm birth or low birth weight risk, and PAH-DNA adducts. These effects also depend on the presence of risk alleles. We investigated the presence of bulky PAH-DNA adducts, plasma 8-iso-PGF_2α (8-iso-prostaglandin F_2α ) and risk allele variants in neonates cord blood and their non-smoking mothers' leucocytes from families that were living in a highly polluted area during 2014-2015. The presence of adducts was significantly associated with both PM_2.5 and PM₁₀ levels, mainly during the last trimester of gestation in both neonates and mothers, while the last month of pregnancy was significant for the association between ozone levels and maternal plasma 8-iso-PGF_2α . Fetal CYP1B1*3 risk allele was associated with increased adduct levels in neonates while the presence of the maternal allele significantly reduced the levels of fetal adducts. Maternal NQO1*2 was associated with lower maternal levels of adducts. Our findings suggest the need to reduce actual PM limits in MCMA. We did not observe a clear association between PM and/or adduct levels and neonate weight, length, body mass index, Apgar or Capurro score. Environ. Mol. Mutagen. 60:428-442, 2019. © 2019 Wiley Periodicals, Inc.

Investigation of spatial and temporal variation of particulate matter in vitro genotoxicity and cytotoxicity in relation to the elemental composition

Even though the outdoor air pollution and its major component Particulate Matter (PM) are recently classified as human carcinogen, attempts to elucidate the underlying mechanisms of PM toxicity are still crucial and continuing with in vitro approaches in various environmental circumstances. Present study investigated the genotoxicity (Comet assay) and the cytotoxicity (lactate dehydrogenase (LDH) leakage and the water-soluble tetrazolium (WST-1) assays) of 30 daily PM_2.5 samples collected in the Kütahya province, to address their daily variability in effects with season (i.e. winter versus summer) and location (i.e. rural versus urban) using A549 human lung cancer epithelial cell line, as well as in relation to their chemical composition, specifically trace elements, organic carbon (OC) and elemental carbon (EC). The genotoxicity, measured by the percentage tail intensity (TI), of the daily PM_2.5 samples at the traffic dense urban station was higher than that of the rural site for 80% of the parallel days. The genotoxicity was significant in the winter at the urban and in the summer at the rural site. Cytotoxicity was the highest for the winter urban samples. The PM_2.5 mass, OC, and EC concentrations were not correlated to DNA damage, while there were correlations with Mn, Fe, Cu and Ba at the rural PM_2.5 samples, and Mn, Co and Ni at the urban samples, respectively. The present study is confirming that the complex composition of PM_2.5 originating from spatial and temporal changes can cause differences in the health effects.

Geospatial analysis of residential proximity to open-pit coal mining areas in relation to micronuclei frequency, particulate matter concentration, and elemental enrichment factors

During coal surface mining, several activities such as drilling, blasting, loading, and transport produce large quantities of particulate matter (PM) that is directly emitted into the atmosphere. Occupational exposure to this PM has been associated with an increase of DNA damage, but there is a scarcity of data examining the impact of these industrial operations in cytogenetic endpoints frequency and cancer risk of potentially exposed surrounding populations. In this study, we used a Geographic Information Systems (GIS) approach and Inverse Distance Weighting (IDW) methods to perform a spatial and statistical analysis to explore whether exposure to PM_2.5 and PM₁₀ pollution, and additional factors, including the enrichment of the PM with inorganic elements, contribute to cytogenetic damage in residents living in proximity to an open-pit coal mining area. Results showed a spatial relationship between exposure to elevated concentrations of PM_2.5, PM₁₀ and micronuclei frequency in binucleated (MNBN) and mononucleated (MNMONO) cells. Active pits, disposal, and storage areas could be identified as the possible emission sources of combustion elements. Mining activities were also correlated with increased concentrations of highly enriched elements like S, Cu and Cr in the atmosphere, corroborating its role in the inorganic elements pollution around coal mines. Elements enriched in the PM_2.5 fraction contributed to increasing of MNBN but seems to be more related to increased MNMONO frequencies and DNA damage accumulated in vivo. The combined use of GIS and IDW methods could represent an important tool for monitoring potential cancer risk associated to dynamically distributed variables like the PM.

Biomass burning particles in the Brazilian Amazon region: Mutagenic effects of nitro and oxy-PAHs and assessment of health risks

Emissions from burning of biomass in the Amazon region have adverse effects on the environment and human health. Herein, particulate matter (PM) emitted from biomass burning in the Amazon region during two different periods, namely intense and moderate, was investigated. This study focused on: i) organic characterization of nitro- and oxy-polycyclic aromatic hydrocarbons (PAHs); ii) assessment of the excess lifetime cancer risk (LCR); and iii) assessment of the in vitro mutagenic effects of extractable organic matter (EOM). Further, we compared the sensitivity of two mutagenicity tests: Salmonella/microsome test and cytokinesis-block micronucleus (CBMN) with human lung cells. Among the nitro-PAHs, 2-nitrofluoranthene, 7-nitrobenz[a]anthracene, 1-nitropyrene, and 3-nitrofluoranthene showed the highest concentrations, while among oxy-PAHs, 2-metylanthraquinone, benz[a]anthracene-7,12-dione, and 9,10-anthraquinone were the most abundant. The LCR calculated for nitro-PAH exposure during intense biomass burning period showed a major contribution of 6-nitrochrysene to human carcinogenic risk. The EOM from intense period was more mutagenic than that from moderate period for both TA98 and YG1041 Salmonella strains. The number of revertants for YG1041 was 5-50% higher than that for TA98, and the most intense responses were obtained in the absence of metabolic activation, suggesting that nitroaromatic compounds with direct-acting frameshift mutagenic activity are contributing to the DNA damage. Treatment of cells with non-cytotoxic doses of EOM resulted in an increase in micronuclei frequencies. The minimal effective dose showed that Salmonella/microsome test was considerably more sensitive in comparison with CBMN mainly for the intense burning period samples. This was the first study to assess the mutagenicity of EOM associated with PM collected in the Amazon region using Salmonella/microsome test. The presence of compounds with mutagenic effects, particularly nitro- and oxy-PAHs, and LCR values in the range of 10^-5 indicate that the population is potentially exposed to an increased risk of DNA damage, mutation, and cancer.

Cell death pathways of particulate matter toxicity

Humans are exposed to various complex mixtures of particulate matter (PM) from different sources. Long-term exposure to high levels of these particulates has been linked to a diverse range of respiratory and cardiovascular diseases that have resulted in hospital admission. The evaluation of the effects of PM exposure on the mechanisms related to cell death has been a challenge for many researchers. Therefore, in this review, we have discussed the effects of airborne PM exposure on mechanisms related to cell death. For this purpose, we have compiled literature data on PM sources, the effects of exposure, and the assays and models used for evaluation, in order to establish comparisons between various studies. The analysis of this collected data suggested divergent responses to PM exposure that resulted in different cell death types (apoptosis, autophagy, and necrosis). In addition, PM induced oxidative stress within cells, which appeared to be an important factor in the determination of cell fate. When the levels of reactive oxygen species were overpowering, the cellular fate was directed toward cell death. This may be the underlying mechanism of the development or exacerbation of respiratory diseases, such as emphysema and chronic obstructive pulmonary diseases. In addition, PM was shown to cause DNA damage and the resulting mutations increased the risk of cancer. Furthermore, several conditions should be considered in the assessment of cell death in PM-exposed models, including the cell culture line, PM composition, and the interaction of the different cells types in in vivo models.

Biomass burning in the Amazon region causes DNA damage and cell death in human lung cells

Most of the studies on air pollution focus on emissions from fossil fuel burning in urban centers. However, approximately half of the world's population is exposed to air pollution caused by biomass burning emissions. In the Brazilian Amazon population, over 10 million people are directly exposed to high levels of pollutants resulting from deforestation and agricultural fires. This work is the first study to present an integrated view of the effects of inhalable particles present in emissions of biomass burning. Exposing human lung cells to particulate matter smaller than 10 µm (PM10), significantly increased the level of reactive oxygen species (ROS), inflammatory cytokines, autophagy, and DNA damage. Continued PM10 exposure activated apoptosis and necrosis. Interestingly, retene, a polycyclic aromatic hydrocarbon present in PM10, is a potential compound for the effects of PM10, causing DNA damage and cell death. The PM10 concentrations observed during Amazon biomass burning were sufficient to induce severe adverse effects in human lung cells. Our study provides new data that will help elucidate the mechanism of PM10-mediated lung cancer development. In addition, the results of this study support the establishment of new guidelines for human health protection in regions strongly impacted by biomass burning.

Mitochondria and mitochondrial DNA as relevant targets for environmental contaminants

The mitochondrial DNA (mtDNA) is a closed circular molecule that encodes, in humans, 13 polypeptides components of the oxidative phosphorylation complexes. Integrity of the mitochondrial genome is essential for mitochondrial function and cellular homeostasis, and mutations and deletions in the mtDNA lead to oxidative stress, mitochondrial dysfunction and cell death. In vitro and in situ studies suggest that when exposed to certain genotoxins, mtDNA accumulates more damage than nuclear DNA, likely owing to its organization and localization in the mitochondrial matrix, which tends to accumulate lipophilic, positively charged molecules. In that regard, several relevant environmental and occupational contaminants have physical-chemical characteristics that indicate that they might accumulate in mitochondria and target mtDNA. Nonetheless, very little is known so far about mtDNA damage and mitochondrial dysfunction due to environmental exposure, either in model organisms or in humans. In this article, we discuss some of the characteristics of mtDNA which render it a potentially relevant target for damage by environmental contaminants, as well as possible functional consequences of damage/mutation accumulation. In addition, we review the data available in the literature focusing on mitochondrial effects of the most common classes of environmental pollutants. From that, we conclude that several lines of experimental evidence support the idea that mitochondria and mtDNA are susceptible and biologically relevant targets for pollutants, and more studies, including mechanistic ones, are needed to shed more light into the contribution of mitochondrial dysfunction to the environmental and human health effects of chemical exposure.

Air quality in the Olona Valley and in vitro human health effects

Air quality is a major point in current health policies in force globally to protect human health and ecosystems. Cardiovascular and lung diseases are the pathologies most commonly associated with air pollution and it has been estimated that exposure to particulate matters and ground-level ozone and nitric oxides caused >500.000 premature deaths in Europe. Although air quality was generally improved in the recent years, further efforts are required to reduce the impact of air pollution on humans. The present study applied a multidisciplinary approach to estimate the adverse effects on the health of the inhabitants of the Olona Valley in the north of Italy. Chemical analyses quantified the air levels of metals, dioxins, PCBs, PAHs and some macropollutants, including total, fine and coarse airborne particles. These results were used as input for the health risk assessment and in vitro bioassays were used to evaluate possible adverse effects on the respiratory tract due to the organic pollutants adsorbed on the airborne particulate matter. Critical alerts were identified from the air characterization and from the chemical-based risk assessment in view of the levels of arsenic, nickel, benzene, fine and coarse particulate matters found in the investigated zone, which can induce severe adverse effects on human health. These findings were confirmed by bioassays with A549 and BEAS-2B cells. We also used the cell transformation assay with BALB/c 3T3 cells to assess the carcinogenicity of the organic extracts of collected particles as an innovative tool to establish the possible chronic effects of inhaled pollutants. No significant changes in morphological transformation were found suggesting that, although the extracts contain compounds with proven carcinogenic potential, in our experimental conditions the levels of these pollutants were too low to induce carcinogenesis as resulted also by the chemical-based risk assessment.

Evaluating the mutagenicity of the water-soluble fraction of air particulate matter: A comparison of two extraction strategies

Many studies have focused on assessing the genotoxic potential of the organic fraction of airborne particulate matter. However, the determination of water-soluble compounds, and the evaluation of the toxic effects of these elements can also provide valuable information for the development of novel strategies to control atmospheric air pollution. To determine an appropriate extraction method for assessing the mutagenicity of the water-soluble fraction of PM, we performed microwave assisted (MW) and ultrasonic bath (US) extractions, using water as solvent, in eight different air samples (TSP and PM10). Mutagenicity and extraction performances were evaluated using the Salmonella/microsome assay with strains TA98 and TA100, followed by chemical determination of water-soluble metals. Additionally, we evaluated the chemical and biological stability of the extracts testing their mutagenic potential and chemically determining elements present in the samples along several periods after extraction. Reference material SRM 1648a was used. The comparison of MW and US extractions did not show differences on the metals concentrations, however positive mutagenic responses were detected with TA98 strain in all samples extracted using the MW method, but not with the US bath extraction. The recovery, using reference material was better in samples extracted with MW. We concluded that the MW extraction is more efficient to assess the mutagenic activity of the soluble fraction of airborne PM. We also observed that the extract freezing and storage over 60 days has a significant effect on the mutagenic and analytical results on PM samples, and should be avoided.

Genetic damage of organic matter in the Brazilian Amazon: a comparative study between intense and moderate biomass burning

BACKGROUND

The biomass burning that occurs in the Amazon region has an adverse effect on environmental and human health. However, in this region, there are limited studies linking atmospheric pollution and genetic damage.

OBJECTIVE

We conducted a comparative study during intense and moderate biomass burning periods focusing on the genetic damage and physicochemical analyses of the particulate matter (PM).

METHOD

PM and black carbon (BC) were determined; organic compounds were identified and quantified using gas chromatography with flame ionization detection, the cyto-genotoxicity test was performed using two bioassays: cytokinesis-block micronucleus (CBMN) in A549 cells and Tradescantia pallida micronucleus (Trad-MCN) assay.

RESULTS

The PM10 concentrations were lower than the World Health Organization air quality standard for 24h. The n-alkanes analyses indicate anthropogenic and biogenic influences during intense and moderate biomass burning periods, respectively. Retene was identified as the most abundant polycyclic aromatic hydrocarbon during both sampling periods. Carcinogenic and mutagenic compounds were identified. The genotoxic analysis through CBMN and Trad-MCN tests showed that the frequency MCN from the intense burning period is significantly higher compared to moderate burning period.

CONCLUSIONS

This is the first study using human alveolar cells to show the genotoxic effects of organic PM from biomass burning samples collected in Amazon region. The genotoxicity of PM can be associated with the presence of several mutagenic and carcinogenic compounds, mainly benzo[a]pyrene. These findings have potential implications for the development of pollution abatement strategies and can minimize negative impact on health.

Airborne urban particles (Milan winter-PM2.5) cause mitotic arrest and cell death: Effects on DNA, mitochondria, AhR binding and spindle organization

Airborne particulate matter (PM) is considered to be an important contributor to lung diseases. In the present study we report that Milan winter-PM2.5 inhibited proliferation in human bronchial epithelial cells (BEAS-2B) by inducing mitotic arrest. The cell cycle arrest was followed by an increase in mitotic-apoptotic cells, mitotic slippage and finally an increase in "classical" apoptotic cells. Exposure to winter-PM10 induced only a slight effect which may be due to the presence of PM2.5 in this fraction while pure combustion particles failed to disturb mitosis. Fewer cells expressing the mitosis marker phospho-histone H3 compared to cells with condensed chromosomes, suggest that PM2.5 induced premature mitosis. PM2.5 was internalized into the cells and often localized in laminar organelles, although particles without apparent plasma membrane covering were also seen. In PM-containing cells mitochondria and lysosomes were often damaged, and in mitotic cells fragmented chromosomes often appeared. PM2.5 induced DNA strands breaks and triggered a DNA-damage response characterized by increased phosphorylation of ATM, Chk2 and H2AX; as well as induced a marked increase in expression of the aryl hydrocarbon receptor (AhR)-regulated genes, CYP1A1, CYP1B1 and AhRR. Furthermore, some disturbance of the organization of microtubules was indicated. It is hypothesized that the induced mitotic arrest and following cell death was due to a premature chromosome condensation caused by a combination of DNA, mitochondrial and spindle damage.

Organic extracts of urban air pollution particulate matter (PM2.5)-induced genotoxicity and oxidative stress in human lung bronchial epithelial cells (BEAS-2B cells)

Traffic is a major source of particulate matter (PM), and ultrafine particulates and traffic intensity probably contribute significantly to PM-related health effects. As a strong relationship between air pollution and motor vehicle-originated pollutants has been shown to exist, air pollution genotoxicity studies of urban cities are steadily increasing. In Korea, the death rate caused by lung cancer is the most rapidly increased cancer death rate in the past 10 years. In this study, genotoxicity of PM2.5 (<2.5μm in aerodynamic diameter particles) collected from the traffic area in Suwon City, Korea, was studied using cultured human lung bronchial epithelial cells (BEAS-2B) as a model system for the potential inhalation health effects. Organic extract of PM2.5 (CE) generated significant DNA breakage and micronucleus formation in a dose-dependent manner (1μg/cm(3)-50μg/cm(3)). In the acid-base-neutral fractionation of PM2.5, neutral samples including the aliphatic (F3), aromatic (F4) and slightly polar (F5) fractions generated significant DNA breakage and micronucleus formation. These genotoxic effects were significantly blocked by scavenging agents [superoxide dismutase (SOD), sodium selenite (SS), mannitol (M), catalase (CAT)]. In addition, in the modified Comet assay using endonucleases (FPG and ENDOIII), CE and its fractions (F3, F4, and F5) increased DNA breakage compared with control groups, indicating that CE and fractions of PM2.5 induced oxidative DNA damage. These results clearly suggest that PM2.5 collected in the Suwon traffic area has genotoxic effects and that reactive oxygen species may play a distinct role in these effects. In addition, aliphatic/chlorinated hydrocarbons, PAH/alkylderivatives, and nitro-PAH/ketones/quinones may be important causative agents of the genotoxic effects.

Seasonal variations in the levels of PAH-DNA adducts in young adults living in Mexico City

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous components of polluted air. The Mexico City Metropolitan Area (MCMA), one of the most densely populated areas in the world, is 2240 m above sea level. At this altitude, less oxygen is available, making combustion less efficient and therefore producing more PAH pollutants. According to the Automatic Monitoring Network in Mexico City (RAMA, for its Spanish initials; http://www.sma.df.gob.mx/simat2/informaciontecnica/index.php?opcion=5&opciondifusion_bd=90), which performs environmental monitoring, the critical air pollutants in Mexico City are ozone and particulate matter (PM). PM emissions increase during the dry season (winter to spring) and decrease during the rainy season (summer to autumn). The bioactivation of some PAHs produces reactive metabolites that bind to DNA, and the presence of elevated levels of PAH-DNA adducts in tissues such as blood lymphocytes represents an elevated risk for the development of cancer. We have compared the levels of PAH-DNA adducts and the percentage of cells with chromosomal aberrations (CWAs) using a matched set of peripheral blood lymphocytes obtained on two separate occasions from young non-smoking inhabitants of the MCMA (n = 92) during the 2006 dry season and the following rainy season. PAH-DNA adducts were analysed using the r7, t8-dihydroxy-t-9, 10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE)-DNA chemiluminescence immunoassay (CIA). The percentages of CWA were determined in cultured lymphocytes from the same individuals. Both DNA adduct levels and chromosomal aberrations were tested for correlation with lifestyle and the polymorphisms of cytochromes P450 CYP1A1 and CYP1B1 as well as glutathione-S-transferases GSTM1 and GSTT1. The levels of PAH-DNA adducts were significantly higher (P < 0.001) in the dry season (10.66 ± 3.05 per 10(9) nt, n = 92) than during the rainy season (9.50 ± 2.85 per 10(9) nt, n = 92) and correlated with the seasonal levels of particulate matter with a diameter of ≤ 10 μm (PM(10)). The percentage of CWA was not seasonally related; however, significant associations between the number of risk alleles and adduct levels in the dry (R = 0.298, P = 0.048) and in the wet seasons (R = 0.473, P = 0.001) were observed.

Inhalation toxicity of particulate matters doped with arsenic induced genotoxicity and altered akt signaling pathway in lungs of mice

In the workplace, the arsenic is used in the semiconductor production and the manufacturing of pigments, glass, pesticides and fungicides. Therefore, workers may be exposed to airborne arsenic during its use in manufacturing. The purpose of this study was to evaluate the potential toxicity of particulate matters (PMs) doped with arsenic (PMs-Arsenic) using a rodent model and to compare the genotoxicity in various concentrations and to examine the role of PMs-Arsenic in the induction of signaling pathway in the lung. Mice were exposed to PMs 124.4 ± 24.5 μg/m³ (low concentration) , 220.2 ± 34.5 μg/m³ (middle concentration) , 426.4 ± 40.3 μg/m³ (high concentration) doped with arsenic 1.4 μg/m³ (Low concentration) ,2.5 μg/m³ (middle concentration) , 5.7 μg/m³ (high concentration) for 4 wks (6 h/d, 5 d/wk) , respectively in the whole-body inhalation exposure chambers. To determine the level of genotoxicity, Chromosomal aberration (CA) assay in splenic lymphocytes and Supravital micronucleus (SMN) assay were performed. Then, signal pathway in the lung was analyzed. In the genotoxicity experiments, the increases of aberrant cells were concentration-dependent. Also, PMs-arsenic caused peripheral blood micronucleus frequency at high concentration. The inhalation of PMs-Arsenic increased an expression of phosphorylated Akt (p-Akt: protein kinase B) and phpsphorylated mammalian target of rapamycin (p-mTOR) at high concentration group. Taken together, inhaled PMs-Arsenic caused genotoxicity and altered Akt signaling pathway in the lung. Therefore, the inhalation of PMs-Arsenic needs for a careful risk assessment in the workplace.

Increased lymphocyte micronucleus frequency in early pregnancy is associated prospectively with pre-eclampsia and/or intrauterine growth restriction

Genome stability is essential for normal foetal growth and development. To date, genome stability in human lymphocytes has not been studied in relation to late pregnancy diseases, such as pre-eclampsia (PE) and intrauterine growth restriction (IUGR), which can be life-threatening to mother and baby and together affect >10% of pregnancies. We performed a prospective cohort study investigating the association of maternal chromosomal damage in mid-pregnancy (20 weeks gestation) with pregnancy outcomes. Chromosome damage was measured using the cytokinesis-block micronucleus cytome (CBMNcyt) assay in peripheral blood lymphocytes. The odds ratio for PE and/or IUGR in a mixed cohort of low- and high-risk pregnancies (N = 136) and a cohort of only high-risk pregnancies (N = 91) was 15.97 (P = 0.001) and 17.85 (P = 0.007), respectively, if the frequency of lymphocytes with micronuclei (MN) at 20 weeks gestation was greater than the mean + 2 SDs of the cohort. These results suggest that the presence of lymphocyte MN is significantly increased in women who develop PE and/or IUGR before the clinical signs or symptoms appear relative to women with normal pregnancy outcomes. The CBMNcyt assay may provide a new approach for the early detection of women at risk of developing these late pregnancy diseases and for biomonitoring the efficacy of interventions to reduce DNA damage, which may in turn ameliorate pregnancy outcome.

Effects of atmospheric pollutants on the Nrf2 survival pathway

BACKGROUND, AIM, AND SCOPE

Atmospheric pollution is a worldwide problem. Exposure to atmospheric pollutants causes toxic cellular effects. One of the mechanisms of toxicity by these pollutants is the promotion of oxidative stress. Several signaling pathways control cellular redox homeostasis. In this respect, nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial transcription factor in the cell's response to oxidative stress.

MAIN FEATURES

In cellular animal models, exposure to atmospheric pollutants activates Nrf2, attenuating its toxic and even its carcinogenic effects. Therefore, we have reviewed the scientific literature in order to indicate that air pollutants, such as particulate matter, polycyclic aromatic hydrocarbons, and gaseous matter, are Nrf2 pathway inductors, triggering self-defense through the establishment of proinflammatory and antioxidant responses.

RESULTS AND DISCUSSION

Exposure to reactive molecules as atmospheric pollutants causes the activation of Nrf2 and the subsequent regulation of the expression of cytoprotective and detoxifying enzymes, as well as antioxidants. Moreover, induction of Nrf2 prior to exposure reduces the harmful effects of pollutants. The present article discusses the protective role of the Nrf2 pathway against different atmospheric pollutant insults.

CONCLUSIONS

Nrf2 regulates the expression of numerous cytoprotective genes that function to detoxify reactive species produced during atmospheric pollutant metabolic reactions. From the papers highlighted in this review, we conclude that Nrf2 has an important role in the defense against atmospheric pollutant-induced toxicity.

PERSPECTIVES

Further studies are needed to understand the signaling events that turn on the system in response to atmospheric pollutant stress. This could allow for the possibility of targeting the pathway for prevention benefits in the near future.