Genotoxic effects in wild rodents (Rattus rattus and Mus musculus) in an open coal mining area

The use of the micronucleus test and comet assay in wild rodents: a historical review and future perspectives

Rodents are considered good models for investigating genotoxic damage and mutagenic alterations caused by xenobiotic agents, due to their occupation of a wide variety of habitats. However, relatively few in situ studies have focused on DNA damage in wild rodents associated with environmental exposure. In this review, we investigate trends in the application of the micronucleus test and comet assay in in situ studies of wild rodents. A total of 33 papers were identified, distributed across 14 different countries. Brazil and Spain had the most published studies (six each), followed by Bulgaria (n = 5), Mexico (n = 4) and Italy (n = 3). Only 24 of the 2,652 recognized rodent species have been the subject of in situ studies, which have most frequently focus on species of the genus Mus. The protocols used for the micronucleus test and comet assay varied widely, although blood and bone marrow were the primary types of tissue used. Given the paucity of studies on wild rodents, we recommend further research, particularly focusing on the use of this group as bioindicators of environmental quality and the standardization of protocols.

Ecotoxicology of heavy metal contamination of Neotropical bats

Although bats are responsible for many ecosystem services on which humans depend, they are frequently exposed to multiple anthropogenic stressors. Heavy metal (HM) exposure is an emerging threat of great significance to bats, yet the toxicity threshold for most metallic elements remains unknown. The greatest diversity of bats worldwide is in the Neotropical region, where ecotoxicological studies are scarce. Thus, this review provides a current overview of the knowledge available on HMs contamination of Neotropical bats. Analysis of the results of 17 articles published between 2000 and 2023 documented a trend of increasing interest in the topic, although it is incipient and in few countries. Of the 226 species known for the Neotropics, 95 have been investigated for metal concentrations. Seven different matrices were used to assess concentrations of heavy metals in tissues, with fur being the subject of eight studies, highlighting the search for non-invasive analysis. Twenty-one HMs were detected in bats, with mercury being the most common. The highest concentrations of this HM were detected in insectivorous/omnivorous bats, highlighting its magnification in this trophic guild compared to frugivorous bats. Copper, lead, and cadmium did not differ significantly among the other trophic guilds. This review shows that there is knowledge about concentrations of heavy metals in several Neotropical species, but knowledge about the impact of these concentrations on bat health is limited, which highlights the need for research to determine critical concentrations that cause damage to bat health, and that guide conservation actions for their populations, as well as environmental monitoring actions for these pollutants.

Analysis of the cytotoxic and genotoxic effects in a population chronically exposed to coal mining residues

During coal mining activities, many compounds are released into the environment that can negatively impact human health. Particulate matter, polycyclic aromatic hydrocarbons (PAHs), metals, and oxides are part of the complex mixture that can affect nearby populations. Therefore, we designed this study to evaluate the potential cytotoxic and genotoxic effects in individuals chronically exposed to coal residues from peripheral blood lymphocytes and buccal cells. We recruited 150 individuals who lived more than 20 years in La Loma-Colombia and 120 control individuals from the city of Barranquilla without a history of exposure to coal mining. In the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay, significant differences in the frequency of micronucleus (MN), nucleoplasmic bridge (NPB), nuclear bud (NBUD), and apoptotic cells (APOP) were observed between the two groups. In the buccal micronucleus cytome (BM-Cyt) assay, a significant formation of NBUD, karyorrhexis (KRX), karyolysis (KRL), condensed chromatin (CC), and binucleated (BN) cells was observed in the exposed group. Considering the characteristics of the study group, a significant correlation for CBMN-Cyt was found between NBUD and vitamin consumption, between MN or APOP and meat consumption, and between MN and age. Moreover, a significant correlation for BM-Cyt was found between KRL and vitamin consumption or age, and BN versus alcohol consumption. Using Raman spectroscopy, a significant increase in the concentration of DNA/RNA bases, creatinine, polysaccharides, and fatty acids was detected in the urine of individuals exposed to coal mining compared to the control group. These results contribute to the discussion on the effects of coal mining on nearby populations and the development of diseases due to chronic exposure to these residues.

Bats are an excellent sentinel model for the detection of genotoxic agents. Study in a Colombian Caribbean region

Wildlife animals have been affected by human activities and the diminution of the areas needed to develop wildlife. In Colombia, artisanal and industrial mining focuses on gold extraction, which uses mercury and causes contamination in water sources. Bats may be susceptible to chemical contamination and primarily to bioaccumulated heavy metal contaminants in the food chain. The primary source of exposure is contaminated food and water ingest, followed by dermic exposition and inhalation. The objective was to evaluategenotoxic damage and mercury concentration in bats. Forty-five samples of blood and organs of bats captured in Ayapel and Majagual were collected. Erythrocytes were searched for micronuclei by peripheral blood smear. Mercury concentration in 45 liver and spleen samples was determined by atomic absorption spectroscopy (DMA80 TRICELL, Milestone Inc, Italy). Bats from four families were studied: Phyllostomidae (6 species), Molossidae (3 species), Vespertilionidae (1 species), and Emballonuridae (1 species). Mercury was found in all bat species from the different dietary guilds. Insectivores had the highest concentration of mercury in the liver (0,23 µg/g) and spleen (0,25 µg/g) and the highest number of micronuclei (260 micronuclei/10,000). The specimens captured in Majagual had the highest frequency of micronuclei (677 micronuclei/10,000), and those captured in Ayapel had the highest mercury concentration (0,833 µg/g). This is the first study in Colombia to report that bats could act as sentinels to the environment's genotoxic chemical agents. Mercury and a high frequency of micronuclei were found in the tissues of captured bats. In addition to mercury contamination, there could also be other contaminants affecting Chiroptera.

Assessing effects of chronic heavy metal exposure through a multibiomarker approach: the case of Liomys irroratus (Rodentia: Heteromyidae)

Wild animals that inhabit inside mine tailings which contain heavy metals are an excellent study model to conduct ecotoxicological studies that analyze chronic metal exposures at low doses (realistic exposures). This study was conducted in Huautla, Morelos, Mexico, in a mining district where 780,000 tons of wastes were deposited in open air. Liomys irroratus is a small mammal species that lives inside these mine tailings. A multibiomarker approach study was performed to analyze metal bioaccumulation levels (biomarker of exposure) by inductively coupled plasma mass spectrometry, DNA damage levels (biomarker of early effects) through the alkaline comet assay, and population genetic structure and diversity (biomarker of permanent effects), using seven microsatellite loci, in 75 L. irroratus individuals, from two mine tailings and one reference site. Concentrations of aluminum, copper, iron, nickel, lead, and zinc were statistically higher in the liver of exposed individuals. Significant DNA damage levels were registered in the mine tailings groups. Aluminum, lead, and nickel had the highest contribution to the genetic damage levels observed, while aluminum and nickel had the highest contribution to genetic diversity effects. A positive and significant relationship was detected between individual genetic diversity (internal relatedness) and genetic damage (DNA single-strand breaks). Genetic structure of L. irroratus populations revealed that the main source of genetic variation was located within populations. We consider that multibiomarker studies in environmental settings using sentinel species are valuable for environmental risk assessment and ecological responses in chronic exposed populations.

Wild black rats (Rattus rattus Linnaeus, 1758) as zoomonitor of genotoxicity and systemic toxicity induced by hazardous emissions from Abule Egba unsanitary landfill, Lagos, Nigeria

Wild black rats (Rattus rattus) inhabiting Abule Egba landfill (AEL) were used as zoomonitor to assess health risk associated with exposure to hazardous chemicals from landfills. Twenty five R. rattus (16♂ and 9♀) captured within AEL and 15 (9♂ and 6♀) (control) caught from Iyano Ipaja (10 km away from AEL) were examined for bone marrow micronucleated polychromatic erythrocytes (MNPCE) and polychromatic erythrocytes/normochromatic erythrocytes (PCE/NCE) ratio, abnormal sperm morphology, alterations in hematological indices and erythrocyte morphology, and histopathology of the viscera using standard protocols. There was significant (p < 0.05) increase in MNPCE but decrease PCE/NCE ratio in bone marrow cells of exposed rats than the reference site. MNPCE was insignificantly higher in male than females. Cauda epididymal sperms from exposed rats showed significant high frequency of teratozoospermia. Erythrocyte count, hemoglobin concentrations, percentage hematocrits, mean corpuscular hemoglobin concentrations, leucocyte count, and lymphocytes decreased while mean corpuscular volume, neutrophils, and mean corpuscular hemoglobin increased in the exposed rats compared to the control. Also, abnormal erythrocyte morphology: acanthocytes, codocytes (target cells), schizocytes, and tear drops significantly increased in the exposed rats. Marginal sexual dimorphism was observed between males and females in the incidence of hematological indices. Histopathological lesions including interstitial edema, hemorrhage, lymphoid depletion, cellular infiltrations, proliferation of the alveolar pneumocytes, necrosis, tissue degeneration, and reduced germinal epithelium were observed in the testes, liver, lungs, heart, kidney, and spleen from the exposed rats compared to the control. Some physicochemicals and metals analyzed in leachates from the landfill are capable of inducing genome instability and systemic toxicity in the exposed rats. Rattus rattus exposed to hazardous chemicals from AEL harbored somatic and germ cell mutations, and tissue damage compared to the control rats. We suggest that R. rattus are useful sentinel for genotoxicity and system toxicity assessment of landfill-polluted sites.Graphical abstract.

Variation in genetic diversity of tree sparrow (Passer montanus) population in long-term environmental heavy metal polluted areas

Genetic diversity is the bedrock of evolution. The "Genetic Erosion" hypothesis posits that environmental pollution could cause reduced genetic diversity. To explore the effects of heavy metal pollution on genetic diversity in natural populations, we selected an area with more than sixty years of heavy metal contamination (Baiyin, BY) and a relatively unpolluted one (Liujiaxia, LJX), and tree sparrow (Passer montanus) as study models. Five tree sparrow populations were sampled in BY at sites differing in heavy metal pollution level. Lower genetic diversity based on seven microsatellite loci was observed in the five tree sparrow populations from BY compared with those from LJX. Analysis of molecular variance indicated no significant genetic differentiation between BY and LJX. However, the observed heterozygosity and allelic richness were negatively correlated to the lead and cadmium concentrations in the primary feathers of tree sparrow. Our results indicated the genetic diversity might have a negative response to long-term environmental heavy metal pollution in tree sparrow, supporting the "Genetic Erosion" hypothesis. Therefore, the findings shed lights on the possible effects of heavy metal pollution on genetic diversity of wild bird populations.

Fish as bioindicators: coal and mercury pollution in Colombia's ecosystems

Mining in Colombia affects 488,672 ha (298,391 in coal mining and 190,281 in gold mining). However, Colombia has insufficient studies on mining and its repercussions, which limits estimates of mining impacts on ecosystems and the human population. Due to the rise of mining activities in Colombia, the negative impacts generated by coal and Hg will also continue to increase. This review analyzes national information levels on coal and Hg in island/coastal/marine as well as freshwater ecosystems and human groups using fishery resources as a framework. This is because fish are the main source of animal protein in marine coastal-island and mainland communities. Here, 15 of 32 Colombian departments have records on total mercury (THg) in water, sediments, fish, and human communities. Around 205 ton/year of mercury is discharged into the ecosystem. In human hair for example (15.3 to 50.15 μg/g), mercury exceeds the international maximum levels allowed (ILA) and the national standard (5.0 μg/g). Mercury levels in freshwater fish show 3.3 μg/g of THg and levels in marine and coastal-island fish are 1.2 μg/g THg exceeding the ILA (0.5 μg/g) standard for fish that will be consumed. Carnivorous species have a THg between 0.04 and 2.55 μg/g suggesting bioaccumulation and magnification of heavy metals. These findings were then compared with available international information.

Chronic exposure to lead and cadmium pollution results in genomic instability in a model biomonitor species (Apodemus flavicollis Melchior, 1834)

Polymetal dust is a common industrial pollutant. While the use of remediation filters and equipment in lead smelters has reduced pollutant emission, surrounding areas remain contaminated due to the long-term transfer of heavy metals along the food chain. Here we assess the mutagenic potential of the lead-zinc smelter near Plovdiv (Bulgaria) situated in an area that has been contaminated with heavy metals for 60 years. We aimed to evaluate the genomic response of the yellow-necked mouse (A. flavicollis), a biomonitor species, in three sampling sites along the pollution gradient. Mice from Strandzha Natural Park were used as a negative control. The bioaccumulation rate of two non-essential heavy metals, lead (Pb) and cadmium (Cd), in liver tissues was determined by atomic absorption spectroscopy. Genetic alterations attributable to chronic exposure to trace levels of heavy metals were assessed in different blood cell populations using two independent methods: a micronucleus test was applied to evaluate the clastogenic and aneugenic alterations in erythrocytes, while a comet assay was used to assess DNA instability, as evidenced by single- and double-stranded breaks and alkali-labile sites, in leucocytes. We observed elevated levels of Pb and Cd in livers derived from mice from the impacted area: the mean Pb concentration (21.38 ± 8.77 μg/g) was two-fold higher than the lowest-observed-adverse-effect levels (LOAELs), while the mean Cd concentration (13.95 ± 9.79 μg/g) was extremely close to these levels. The mean levels of Pb and Cd in livers derived from mice from the impacted area were 31-fold and 63-fold higher, respectively, than the levels measured in mice from the control area. The mean frequency of micronuclei was significantly higher (four-fold) than that observed in the control animals. Furthermore, parameters measured by the comet assay, % tail DNA, tail length and tail moment, were significantly higher in the impact area, indicating the degree of genetic instability caused by exposure to heavy metals. In conclusion, this study shows that despite the reported reduction in lead and cadmium emissions in Bulgaria in recent years, A. flavicollis individuals inhabiting areas subject to long-term contamination exhibit significant signs of DNA damage.

Pulmonary oxidative stress in wild bats exposed to coal dust: A model to evaluate the impact of coal mining on health

This study aimed to verify possible alterations involving histological and oxidative stress parameters in the lungs of wild bats in the Carboniferous Basin of Santa Catarina (CBSC) state, Southern Brazil, as a means to evaluate the impact of coal dust on the health of wildlife. Specimens of frugivorous bat species Artibeus lituratus and Sturnira lilium were collected from an area free of coal dust contamination and from coal mining areas. Chemical composition, histological parameters, synthesis of oxidants and antioxidant enzymes, and oxidative damage in the lungs of bats were analyzed. Levels of Na, Cl, Cu, and Br were higher in both species collected in the CBSC than in the controls. Levels of K and Rb were higher in A. lituratus, and levels of Si, Ca, and Fe were higher in S. lilium collected in the carboniferous basin. Both bat species inhabiting the CBSC areas exhibited an increase in the degree of pulmonary emphysema compared to their counterparts collected from control areas. Sturnira lilium showed increased reactive oxygen species (ROS) and 2',7'-dichlorofluorescein (DCF) levels, while A. lituratus showed a significant decrease in nitrite levels in the CBSC samples. Superoxide dismutase (SOD) activity did not change significantly; however, the activity of catalase (CAT) and levels of glutathione (GSH) decreased in the A. lituratus group from CBSC compared to those in the controls. There were no differences in NAD(P)H quinone dehydrogenase 1 protein (NQO1) abundance or nitrotyrosine expression among the different groups of bats. Total thiol levels showed a significant reduction in A. lituratus from CBSC, while the amount of malondialdehyde (MDA) was higher in both A. lituratus and S. lilium groups from coal mining areas. Our results suggested that bats, especially A. lituratus, living in the CBSC could be used as sentinel species for harmful effects of coal dust on the lungs.

Intergenerational effects of coal dust on Tribolium castaneum, Herbst

Coal dust is a primary air contaminant from coal mining operations that produces harmful health effects. However, it is unclear to what extent its detrimental properties would impact future generations, and whether alterations in the progenies might be concentration-dependent. The aim of this study was to determine the intergenerational effects of chronic exposure to coal dust on the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), at three life stages. Groups of fifty adult insects were exposed during 30 days at different concentrations of coal dust mixed with ground oats as food substrate (0, 0.25, 0.5, 1.0 and 2.0% weight/weight), both with a particle size <38 μm. The LC₅₀ for F0 insects was 1.07%, whereas for larvae and adults from F1, values were 0.53 and 0.89%, respectively. Pathological findings assessed at F1 revealed a coal dust concentration-dependent frequency of several morphological abnormalities, including larvae without antenna or extremities, lack of T1, T2, T3 legs, loss of urogomphi, and the presence of abnormal protuberances. It was found that a considerable number of F1 larvae derived from parental beetles did not achieve a complete conversion into the next growth stage. Pupae with undeveloped eyes and adults with malformed elytra, as well as necrosis, were recurrently observed at high concentrations. Finally, adults exposed to 1% coal dust overexpressed genes related to oxidative stress (nuclear factor erythroid 2-related factor 2, Nrf2) and synaptic transmission (GABA-gated ion channel, Grd). In short, coal dust particles induced intergenerational effects on T. castaneum, highlighting the need to further study the impact of this airborne pollutant on wildlife and human populations.

Heavy metal accumulation and genotoxic effects in levant vole (Microtus guentheri) collected from contaminated areas due to mining activities

Heavy metal contamination is a serious environmental problem commonly monitored in various organisms. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to evaluate the adverse effects of marble and stone quarries on the Levant vole, Microtus guentheri, inhabiting some polluted sites. In this context, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd, and Hg) in the organs (skins, bones, muscles, livers and kidneys) of the biological specimens, and the comet assay revealed DNA damage in blood lymphocytes for the first time. This study was conducted at close to the marble and stone quarries at Korkuteli, Antalya-Turkey during spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all polluted sites (sites 1-5) was significantly higher than that of controls, while in autumn it was higher in samples from three sites (sites 3-5). In terms of heavy metal distribution in organs, we found depositions of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb primarily in the skin with its derivatives, Cu and Cd deposits in the kidney, Cu, Cd and B deposits in the liver, and As and Pb depositions in the bones. The study shows that certain organs (especially skin with its derivatives) and blood lymphocytes of Levant vole can be used as ideal indicators of heavy metal pollution. Our results suggest that the Korkuteli area could already be under the threat of heavy metal pollution.

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.

Genetic effects in Helix aspersa near a coal plant revealed by the micronucleus test

Coal plants can be a major source of mutagenic pollutants. In this study we used the common land snail Helix aspersa, to detect the mutagenic effect of pollution from a coal plant in central Italy applying the micronucleus test (MN) on snail's haemocytes and evaluating trace elements concentration (As Cd, Pb, Hg, and Zn) in soil and snails. Snails from a biological farm were exposed for 13 days in five locations at different distances from the plant. Wild snails collected in the same locations were also analysed. MN frequency in exposed snails was significantly higher in four locations within 10 km from to the plant, with respect to the control and the farthest location. Comparing the MN frequency between farmed and wild snails, a significantly higher frequency emerged for the exposed snails in all locations except the farthest, likely indicating adaptation or selection of the wild organisms due to chronic exposure to pollutants. In natural snails significantly higher MN frequencies with near the plant emerged as well. Trace elements analysis showed significant correlations between MN frequencies and both Zn and As concentrations in soil, for both exposed and wild snails, and Zn and Pb concentrations in exposed snails. Our results were consistent with those previously obtained when evaluating primary DNA damage in natural snails from the same area and show that the snails near the plant were affected by a permanent cytogenetic damage. Moreover, they confirm the suitability of snails for biomonitoring the presence of pollutants with mutagenic effect.

Embryonic exposure to an aqueous coal dust extract results in gene expression alterations associated with the development and function of connective tissue and the hematological system, immunological and inflammatory disease, and cancer in zebrafish

Coal mining is one of the economic activities with the greatest impact on environmental quality. At all stages contaminants are released as particulates such as coal dust. The first aim of this study was to obtain an aqueous coal dust extract and characterize its composition in terms of trace elements by ICP-MS. In addition, the developmental toxicity of the aqueous coal extract was evaluated using zebrafish (Danio rerio) after exposure to different concentrations (0-1000 ppm; μg mL^-1) to establish acute toxicity, morphology and transcriptome changes. Trace elements within the aqueous coal dust extract present at the highest concentrations (>10 ppb) included Sr, Zn, Ba, As, Cu and Se. In addition, Cd and Pb were found in lower concentrations. No significant difference in mortality was observed (p > 0.05), but a delay in hatching was found at 0.1 and 1000 ppm (p < 0.05). No significant differences in morphological characteristics were observed in any of the treatment groups (p > 0.05). Transcriptomic results of zebrafish larvae revealed alterations in 77, 61 and 1376 genes in the 1, 10, and 100 ppm groups, respectively. Gene ontology analysis identified gene alterations associated with the development and function of connective tissue and the hematological system, as well as pathways associated with apoptosis, the cell cycle, transcription, and oxidative stress including the MAPK signaling pathway. In addition, altered genes were associated with cancer; connective tissue, muscular, and skeletal disorders; and immunological and inflammatory diseases. Overall, this is the first study to characterize gene expression alterations in response to developmental exposure to aqueous coal dust residue from coal mining with transcriptome results signifying functions and systems to target in future studies.

Cytogenetic instability in populations with residential proximity to open-pit coal mine in Northern Colombia in relation to PM10 and PM2.5 levels

Epidemiological studies indicate that living in proximity to coal mines is correlated with numerous diseases including cancer, and that exposure to PM₁₀ and PM_2.5 components could be associated with this phenomenon. However, the understanding of the mechanisms by which PM exerts its adverse effects is still incomplete and comes mainly from studies in occupationally exposed populations. The aims of this study were to: (1) evaluate DNA damage in lymphocytes assessing the cytokinesis-block micronucleus cytome assay (CBMN-cyt) parameters; (2) identify aneugenic or clastogenic effects in lymphocytes of exposed populations using CREST immunostaining for micronuclei; (3) evaluate multi-elemental composition of atmospheric particulate matter; and (4) verify relation between the DNA damage and PM_2.5 and PM₁₀ levels around the mining area. Analysis revealed a significant increase in micronuclei frequency in binucleated (MNBN) and mononucleated (MNMONO) cells of individuals with residential proximity to open-pit coal mines compared to residents from non-mining areas. Correlation analysis demonstrated a highly significant association between PM_2.5 levels, MNBN frequencies and CREST+ micronuclei induction in exposed residents. These results suggest that PM_2.5 fraction generated in coal mining activities may induce whole chromosome loss (aneuploidy) preferentially, although there are also chromosome breaks. Analysis of the chemical composition of PM_2.5 by PIXE demonstrated that Si, S, K and Cr concentrations varied significantly between coal mining and reference areas. Enrichment factor values (EF) showed that S, Cr and Cu were highly enriched in the coal mining areas. Compared to reference area, mining regions had also higher concentrations of extractable organic matter (EOM) related to nonpolar and polar compounds. Our results demonstrate that PM_2.5 fraction represents the most important health risk for residents living near open-pit mines, underscoring the need for incorporation of ambient air standards based on PM_2.5 measures in coal mining areas.

Cytotoxic, genotoxic and mutagenic evaluation of surface waters from a coal exploration region

Coal mining generates a considerable amount of waste, which is disposed of in piles or dams near mining sites. As a result, leachates may reach rivers and streams, promoting the wide dispersion of contaminants in solution and as particulate matter. The present study evaluated the cytotoxic, genotoxic, and mutagenic action of surface waters collected around a thermoelectric power plant and the largest mining area in Brazil (Candiota). Four sites in Candiota stream were selected, and samples were collected in winter and summer. Water samples were analyzed using the comet and CBMN assays in V79 and HepG2 cells. Furthermore, genotoxicity of water samples was evaluated in vivo using the SMART in Drosophila melanogaster. In addition, polycyclic aromatic hydrocarbons and inorganic elements were quantified. The results indicate that water samples exhibited no genotoxic and mutagenic activities, whether in vitro or in vivo. On the other hand, surface water samples collected in sites near the power plant in both summer and winter inhibited cell proliferation and induced increased frequencies of V79 cell death, apoptosis, and necrosis. The cytotoxicity observed may be associated with the presence of higher concentration of inorganic elements, especially aluminum, silicon, sulfur, titanium and zinc at sites 1 and 2 in the stream, as well as with the complex mixture present in the coal, in both seasons. Therefore, the results obtained point to the toxicity potential of water samples with the influence of coal mining and combustion processes and the possible adverse effects on the health of exposed organisms.

DNA damage induced by coal dust, fly and bottom ash from coal combustion evaluated using the micronucleus test and comet assay in vitro

Coal mining and combustion generating huge amounts of bottom and fly ash are major causes of environmental pollution and health hazards due to the release of polycyclic aromatic hydrocarbons (PAH) and heavy metals. The Candiota coalfield in Rio Grande do Sul, is one of the largest open-cast coal mines in Brazil. The aim of this study was to evaluate genotoxic and mutagenic effects of coal, bottom ash and fly ash samples from Candiota with the comet assay (alkaline and modified version) and micronucleus test using the lung fibroblast cell line (V79). Qualitative and quantitative analysis of PAH and inorganic elements was carried out by High Performance Liquid Chromatography (HPLC) and by Particle-Induced X-ray Emission (PIXE) techniques respectively. The samples demonstrated genotoxic and mutagenic effects. The comet assay modified using DNA-glicosilase formamidopirimidina (FPG) endonuclease showed damage related to oxidative stress mechanisms. The amount of PAHs was higher in fly ash followed by pulverized coal. The amount of inorganic elements was highest in fly ash, followed by bottom ash. It is concluded that the samples induce DNA damage by mechanisms that include oxidative stress, due to their complex composition, and that protective measures have to be taken regarding occupational and environmental hazards.

Chemical and toxicological effects of medicinal Baccharis trimera extract from coal burning area

The entire process of power generation, extraction, processing and use of coal strongly impact water resources, soil, air quality and biota leads to changes in the fauna and flora. Pollutants generated by coal burning have been contaminating plants that grow in area impacted by airborne pollution with high metal contents. Baccharis trimera is popularly consumed as tea, and is widely developed in Candiota (Brazil), one of the most important coal burning regions of the Brazil. This study aims to investigate the phytochemical profile, in vivo genotoxic and mutagenic potential of extracts of B. trimera collected from an exposed region to pollutants generated by coal burning (Candiota City) and other unexposed region (Bagé City), using the Comet assay and micronucleus test in mice and the Salmonella/microsome short-term assay. The HPLC analyses indicated higher levels of flavonoids and phenolic acids for B. trimera aqueous extract from Bagé and absence of polycyclic aromatic hydrocarbons for both extracts. The presence of toxic elements such as cobalt, nickel and manganese was statistically superior in the extract from Candiota. For the Comet assay and micronucleus test, the mice were treated with Candiota and Bagé B. trimera aqueous extracts (500-2000 mg/kg). Significant genotoxicity was observed at higher doses treated with B. trimera aqueous extract from Candiota in liver and peripheral blood cells. Micronuclei were not observed but the results of the Salmonella/microsome short-term assay showed a significant increase in TA98 revertants for B. trimera aqueous extract from Candiota. The extract of B. trimera from Candiota bioacumulated higher levels of trace elements which were associated with the genotoxic effects detected in liver and peripheral blood cells.

Evaluation of the genotoxic potential of soil contaminated with mineral coal tailings on snail Helix aspersa

Coal remains an important source of energy, although the fuel is a greater environmental pollutant. Coal is a mixture of several chemicals, especially inorganic elements and polycyclic aromatic hydrocarbons (PAH). Many of these compounds have mutagenic and carcinogenic effects on organisms exposed to this mineral. In the town of Charqueadas (Brazil), the tailings from mining were used for landfill in the lower areas of the town, and the consequence is the formation of large deposits of this material. The purpose of this study was to evaluate the genotoxic potential of soil samples contaminated by coal waste in different sites at Charqueadas, using the land snail Helix aspersa as a biomonitor organism. Thirty terrestrial snails were exposed to different treatments: 20 were exposed to the soil from two different sites in Charqueadas (site 1 and 2; 10 in each group) and 10 non-exposed (control group). Hemolymph cells were collected after 24h, 5days and 7days of exposure and comet assay, micronucleus test, oxidative stress tests were performed. Furthermore, this study quantified the inorganic elements present in soil samples by the PIXE technique and polycyclic aromatic hydrocarbons (PAH) by HPLC. This evaluation shows that, in general, soils from sites in Charqueadas, demonstrated a genotoxic effect associated with increased oxidative stress, inorganic and PAH content. These results demonstrate that the coal pyrite tailings from Charqueadas are potentially genotoxic and that H. aspersa is confirmed to be a sensitive instrument for risk assessment of environmental pollution.

The Comet Assay and its applications in the field of ecotoxicology: a mature tool that continues to expand its perspectives

Since Singh and colleagues, in 1988, launched to the scientific community the alkaline Single Cell Gel Electrophoresis (SCGE) protocol, or Comet Assay, its uses and applications has been increasing. The thematic areas of its current employment in the evaluation of genetic toxicity are vast, either in vitro or in vivo, both in the laboratory and in the environment, terrestrial or aquatic. It has been applied to a wide range of experimental models: bacteria, fungi, cells culture, arthropods, fishes, amphibians, reptiles, mammals, and humans. This document is intended to be a comprehensive review of what has been published to date on the field of ecotoxicology, aiming at the following main aspects: (i) to show the most relevant experimental models used as bioindicators both in the laboratory and in the field. Fishes are clearly the most adopted group, reflecting their popularity as bioindicator models, as well as a primary concern over the aquatic environment health. Amphibians are among the most sensitive organisms to environmental changes, mainly due to an early aquatic-dependent development stage and a highly permeable skin. Moreover, in the terrestrial approach, earthworms, plants or mammalians are excellent organisms to be used as experimental models for genotoxic evaluation of pollutants, complex mix of pollutants and chemicals, in both laboratory and natural environment. (ii) To review the development and modifications of the protocols used and the cell types (or tissues) used. The most recent developments concern the adoption of the enzyme linked assay (digestion with lesion-specific repair endonucleases) and prediction of the ability to repair of oxidative DNA damage, which is becoming a widespread approach, albeit challenging. For practical/technical reasons, blood is the most common choice but tissues/cells like gills, sperm cells, early larval stages, coelomocytes, liver or kidney have been also used. (iii) To highlight correlations with other biomarkers. (iv) To build a constructive criticism and summarize the needs for protocol improvements for future test applications within the field of ecotoxicology. The Comet Assay is still developing and its potential is yet underexploited in experimental models, mesocosmos or natural ecosystems.

Altered gene expression in HepG2 cells exposed to a methanolic coal dust extract

Exposure to coal dust has been associated with different chronic diseases and mortality risk. This airborne pollutant is produced during coal mining and transport activities, generating environmental and human toxicity. The aim of this study was to determine the effects of a coal dust methanolic extract on HepG2, a human liver hepatocellular carcinoma cell line. Cells were exposed to 5-100ppm methanolic coal extract for 12h, using DMSO as control. MTT and comet assays were used for the evaluation of cytotoxicity and genotoxicity, respectively. Real time PCR was utilized to quantify relative expression of genes related to oxidative stress, xenobiotic metabolism and DNA damage. Coal extract concentrations did not induce significant changes in HepG2 cell viability after 12h exposure; however, 50 and 100ppm of the coal extract produced a significant increase in genetic damage index with respect to negative control. Compared to vehicle control, mRNA CYP1A1 (up to 163-fold), NQO1 (up to 4.7-fold), and GADD45B (up to 4.7-fold) were up regulated, whereas PRDX1, SOD, CAT, GPX1, XPA, ERCC1 and APEX1 remained unaltered. This expression profile suggests that cells exposed to coal dust extract shows aryl hydrocarbon receptor-mediated alterations, changes in cellular oxidative status, and genotoxic effects. These findings share some similarities with those observed in liver of mice captured near coal mining areas, and add evidence that living around these industrial operations may be negatively impacting the biota and human health.

Genetic damage in coal miners evaluated by buccal micronucleus cytome assay

During coal mining activities, large quantities of coal dust, ashes, polycyclic aromatic hydrocarbons and metals are released into the environment. This complex mixture presents one of the most important occupational hazards for health of workers. The aim of the present study was to evaluate the genetic damage together with the presence of inorganic elements, in an exposed workers population to coal mining residues of Guajira-Colombia. Thus, 100 exposed workers and 100 non-exposed control individuals were included in this study. To determine genetic damage we assessed the micronucleus (MN) frequencies and nuclear buds in buccal mucosa samples (BMCyt) assay, which were significantly higher in the exposed group than non-exposed control group. In addition, karyorrhectic and karyolytic cells were also significantly higher in the exposed group (cell death). No significant difference was observed between the exposed groups engaged in different mining activities. No correlation between age, alcohol consumption, time of service and MN assay data were found in this study. However, the content of inorganic elements in blood samples analyzed by a Particle-induced X-ray emission technique (PIXE) showed higher values of silicon (Si) and aluminum (Al) in the exposed group. In this study we discuss the possibility of DNA damage observed in the mine workers cells be a consequence of oxidative damage.

Baccharis trimera (Less.) DC as genotoxicity indicator of exposure to coal and emissions from a thermal power plant

During coal combustion, hazardous elements are discharged that impair environmental quality. Plant cover is the first available surface for the atmospheric pollutants in terrestrial ecosystems. The aim of this study was to evaluate genotoxicity in the aqueous extract of the native plant, Baccharis trimera, exposed to coal and emissions from a thermal power plant (coal-fired power plant in Candiota, Brazil), correlating seasonality, wind tunnel predominance, and presence of inorganic elements. The presence of inorganic elements in the aerial parts of B. trimera was analyzed by particle-induced X-ray emission (PIXE) spectrometry, and genotoxicity was evaluated by ex vivo comet assay. The genotoxic effects of aqueous extracts of B. trimera from four sites located in the area around power plant were analyzed by comet assay in peripheral human lymphocytes. Winter samples showed greater levels of metals than summer samples. Genotoxicity was detected in B. trimera extracts collected from the region exposed to extraction and burning coal. Extracts from the site impacted by the dominant wind induced more damage to DNA than those from other sites. Based on our data, we can suggest that in winter the inorganic elements from extraction and burning of coal and carried through the wind tunnel were responsible for the genotoxicity observed in aqueous extract of B. trimera.

Phytotoxicity assessment of a methanolic coal dust extract in Lemna minor

Coal mining generates negative effects on environment, human health, hydrodynamics of mining areas and biodiversity. However, the impacts of this activity are less known in plants. Lemna minor is one of the most commonly used plants in aquatic toxicity tests due to its ubiquitous distribution in ponds and lakes, culture conditions and the free-floating habitat that exposes it to hydrophobic as well as dissolved compounds. The goal of this research was to evaluate the effects of a methanolic coal dust extract on L. minor. Macrophytes were exposed to six different concentrations of coal extract (from 7.81 to 250 mg/L) for 5 days, following the OECD test guideline 221. The coal extract had a half inhibitory concentration (IC50) of 99.66 (184.95-54.59) mg/L for the number of fronds. Several signs of toxicity such as chlorosis, reduction in the size of the fronds, abscission of fronds and roots, and the presence of necrotic tissues were observed at concentrations lower than the IC50. Preliminary Gas Chromatography-Mass Spectrometry analysis of the coal dust extract revealed the presence of several compounds, including, among others, alkanes, carboxylic acids and polycyclic aromatic hydrocarbons (PAHs), these lasts, may be responsible for some of the observed effects. These results demonstrated that coal dust has phytotoxic effects and should not be considered as an inert material.

Population cancer risks associated with coal mining: a systematic review

Background

Coal is produced across 25 states and provides 42% of US energy. With production expected to increase 7.6% by 2035, proximate populations remain at risk of exposure to carcinogenic coal products such as silica dust and organic compounds. It is unclear if population exposure is associated with increased risk, or even which cancers have been studied in this regard.

Methods

We performed a systematic review of English-language manuscripts published since 1980 to determine if coal mining exposure was associated with increased cancer risk (incidence and mortality).

Results

Of 34 studies identified, 27 studied coal mining as an occupational exposure (coal miner cohort or as a retrospective risk factor) but only seven explored health effects in surrounding populations. Overall, risk assessments were reported for 20 cancer site categories, but their results and frequency varied considerably. Incidence and mortality risk assessments were: negative (no increase) for 12 sites; positive for 1 site; and discordant for 7 sites (e.g. lung, gastric). However, 10 sites had only a single study reporting incidence risk (4 sites had none), and 11 sites had only a single study reporting mortality risk (2 sites had none). The ecological study data were particularly meager, reporting assessments for only 9 sites. While mortality assessments were reported for each, 6 had only a single report and only 2 sites had reported incidence assessments.

Conclusions

The reported assessments are too meager, and at times contradictory, to make definitive conclusions about population cancer risk due to coal mining. However, the preponderance of this and other data support many of Hill’s criteria for causation. The paucity of data regarding population exposure and risk, the widespread geographical extent of coal mining activity, and the continuing importance of coal for US energy, warrant further studies of population exposure and risk.

Assessment of heavy metal content and DNA damage in Hypsiboas faber (anuran amphibian) in coal open-casting mine

The aims of the study were to determine the heavy metal content in the tissues of Hypsiboas faber from a coal mining area and to compare the DNA damage in the blood cells of these animals with that of animals living in an unpolluted area. The heavy metal content was detected according to the technique of Particle-Induced X-ray Emission (PIXE) and the DNA damage was assessed by the Comet assay. Our results reveal that the specimens of H. faber collected from the coal mining area exhibited elements of order Fe>Cu>Al>Zn>Rb>Mn>Br, independently of the organ. The values of Comet assay parameters (DNA damage index and DNA damage frequency) were significantly higher in specimens collected from the coal mining area than in the reference animals. Our study concludes that the coal mining residues are genotoxic to amphibians and may have adverse effects on soil, water, vegetation and wild animals.

Metal bioaccumulation, genotoxicity and gene expression in the European wood mouse (Apodemus sylvaticus) inhabiting an abandoned uranium mining area

Genotoxic effects caused by the exposure to wastes containing metals and radionuclides were investigated in the European wood mice (Apodemus sylvaticus). The animals were captured in the surroundings of an abandoned uranium mining site. DNA damage was assessed by comet assay; gene expression and single nucleotide polymorphisms (SNPs) were assessed, respectively, by Real-Time PCR and melt curve analysis. The bioaccumulation of metals in the liver, kidney and bones was also determined to help clarify cause-effect relationships. Results confirmed the bioaccumulation of cadmium and uranium in organisms exposed to uranium mining wastes. P53 gene was found to be significantly up-regulated in the liver of those organisms and SNPs in the Rb gene were also detected in the kidney. Our results showed that uranium mining wastes caused serious DNA damage resulting in genomic instability, disclosed by the significant increase in DNA strand breaks and P53 gene expression disturbance. These effects can have severe consequences, since they may contribute for the emergence of serious genetic diseases. The fact that mice are often used as bioindicator species for the evaluation of risks of environmental exposure to humans, raises concerns on the risks for human populations living near uranium mining areas.

Evaluation of genetic damage in open-cast coal mine workers using the buccal micronucleus cytome assay

Coal is the largest fossil fuel source used for the generation of energy. However, coal extraction and its use constitute important pollution factors; thus, risk characterization and estimation are extremely important for the safety of coal workers and the environment. Candiota is located to the southeast of the state of Rio Grande do Sul and has the largest coal reserves in Brazil, and the largest thermal power complex in the state. In the open-cast mines, the coal miners are constantly exposed to coal dust. The human buccal micronucleus cytome (BMCyt) assay has been used widely to investigate biomarkers for DNA damage, cell death, and basal cell frequency in buccal cells. The aim of this study was to assess whether prolonged exposure to coal dust could lead to an increase in genomic instability, cell death, and frequency of basal cells using the BMCyt assay. In the analysis of epithelial cells, the exposed group (n = 41) presented with a significantly higher frequency of basal cells, micronuclei in basal and differentiated cells, and binucleated cells compared to the non-exposed group (n = 29). The exposed group showed a significantly lower frequency of condensed chromatin cells than the non-exposed group. However, we found no correlation between DNA damage and metal concentration in the blood of mine workers. DNA damage observed in the mine workers may be a consequence of oxidative damage resulting from exposure to coal residue mixtures. In addition, our findings confirm that the BMCyt assay can be used to identify occupational risk.

Genotoxic effects in blood cells of Mus musculus and Iguana iguana living near coal mining areas in Colombia

Coal is a mixture of chemicals with the capacity of promoting biochemical changes that may lead to DNA damage. In this study, the comet assay in peripheral blood cells, and the micronucleus test in blood smears were used to evaluate potential genotoxic effects derived from exposure to coal mining activities on wild populations of Mus musculus and Iguana iguana. Four locations from Colombia were evaluated: La Loma and La Jagua de Ibirico, two municipalities located near coal mining fields at the Department of Cesar; and Valledupar and Arjona, cities used as reference sites, both localized at least 100 and 200km far from the mines, respectively. Compared to Valledupar and Arjona, animals collected in close proximity to coal mining areas showed highest percentages of DNA damage for both species, evidencing that living around coal mining fields may result in an increase of DNA lesions in blood cells of rodents and reptiles. The results for micronucleus test were conflicting. Mice from Arjona had greater number of cells with micronucleus than those from the other studied locations, probably as a result of infection found by blood parasites. In summary, it was demonstrated that animals living around coal mining areas have a greater chance of having DNA damage, as measured by the comet assay, than those from sites far from the coal dust source.

Assessment of DNA damage in coal open-cast mining workers using the cytokinesis-blocked micronucleus test and the comet assay

Coal mining is one of the most important causes of environmental pollution, as large quantities of coal dust particles are emitted. Colombia-South America has large natural coal reserves and "El Cerrejón" is the world's largest open-cast mine located in the northern department of Guajira. The aim of the present study was to evaluate genotoxic effects in a population exposed to coal residues from the open-cast mine "El Cerrejón". 100 exposed workers and 100 non-exposed control individuals were included in this study. The exposed group was divided according to different mining area activities: (i). Transport of extracted coal, (ii). Equipment field maintenance, (iii). Coal stripping and, (iv). Coal embarking. Blood samples were taken to investigate biomarkers of genotoxicity, specifically, primary DNA damage as damage index (DI), tail length and% of tail DNA using the Comet assay (alkaline version) and chromosome damage as micronucleus (MN) frequency in lymphocytes. Both biomarkers showed statistically significantly higher values in the exposed group compared to the non-exposed control group. No difference was observed between the exposed groups executing different mining activities. These results indicate that exposure to coal mining residues may result in an increased genotoxic exposure in coal mining workers. We did not find a correlation between age, alcohol consumption and service time with the biomarkers of genotoxicity. Our results are the first data of genotoxic effects induced by coal mining exposure in Colombia, and thus, contribute to the exploration of test batteries use for monitoring of exposed populations and may stimulate designing control, hygiene and prevention strategies for occupational health risk assessment in developing countries.

Evaluation of the genotoxic potential of the mineral coal tailings through the Helix aspersa (Müller, 1774)

Coal mining is an activity with a high potential for environmental pollution. Coal has been described as the most significant pollutant of all the fossil fuels, containing a heterogeneous mixture. Many elements present in coal byproducts as well as coal tailings are rich in potentially toxic and genotoxic metals, which ultimately lead to profound changes in cells, tissues, populations, and ecosystems. The purpose of this study was to assess the genotoxic potential of the mineral coal tailings using the land snail Helix aspersa. Animals were divided in three groups, clustered in plexiglass cages: control (animals fed with organic lettuce), coal tailings (animals living in a layer of pyrite tailings and fed with organic lettuce), and mine lettuce (animals fed with lettuce grown in an area located in a deposit of coal tailings). The hemolymph was collected at different exposure times (24 h, 48 h, 72 h, 96 h, 1 week, 2 weeks, 3 weeks, and 1 month) for comet assay analyses. Results showed that the animals of the coal tailings and mine lettuce groups presented higher levels of DNA damage in relation to the control group at all exposure times, but with a peak of DNA damage in 48 h and 96 h. These results demonstrate that the coal pyrite tailings are potentially genotoxic and that H. aspersa has proven to be a sensitive instrument for a better risk assessment of environmental pollution.