The dangerous link between coal dust exposure and DNA damage: unraveling the role of some of the chemical agents and oxidative stress

Exposure to coal mining dust poses a substantial health hazard to individuals due to the complex mixture of components released during the extraction process. This study aimed to assess the oxidative potential of residual coal mining dust on human lymphocyte DNA and telomeres and to perform a chemical characterization of coal dust and urine samples. The study included 150 individuals exposed to coal dust for over ten years, along with 120 control individuals. The results revealed significantly higher levels of DNA damage in the exposed group, as indicated by the standard comet assay, and oxidative damage, as determined by the FPG-modified comet assay. Moreover, the exposed individuals exhibited significantly shorter telomeres compared to the control group, and a significant correlation was found between telomere length and oxidative DNA damage. Using the PIXE method on urine samples, significantly higher concentrations of sodium (Na), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), iron (Fe), zinc (Zn), and bromine (Br) were observed in the exposed group compared to the control group. Furthermore, men showed shorter telomeres, greater DNA damage, and higher concentrations of nickel (Ni), calcium (Ca), and chromium (Cr) compared to exposed women. Additionally, the study characterized the particles released into the environment through GC-MS analysis, identifying several compounds, including polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene, naphthalene, anthracene, 7H-benzo[c]fluorene, phenanthrene, pyrene, benz[a]anthracene, chrysene, and some alkyl derivatives. These findings underscore the significant health risks associated with exposure to coal mining dust, emphasizing the importance of further research and the implementation of regulatory measures to safeguard the health of individuals in affected populations.

Toxicological potential of Aloysia gratissima: Insights from chemical analysis and in vitro studies

ETHNOPHARMACOLOGICAL RELEVANCE

Aloysia gratissima leaves are popularly used to treat respiratory, digestive, and nervous system disorders. Several studies have been carried out to determine the biological activity of A. gratissima, such as its antibacterial and anti-edematogenic activities, but despite the beneficial uses of A. gratissima, few studies have examined the toxicological profile of this plant.

AIM OF THE STUDY

This study aimed to determine the chemical composition, cytotoxic, genotoxic, mutagenic potential, and antioxidant activity of an aqueous extract of A. gratissima leaves (AG-AEL).

MATERIAL AND METHODS

The phytochemical constitution of AG-AEL was assessed by colorimetric analyses and High-performance liquid chromatography (HPLC). The inorganic elements were detected by Particle-Induced X-ray Emission (PIXE). The antioxidant, cytotoxicity, genotoxic, and mutagenic activities were evaluated in vitro by Di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH), Sulforhodamine B (SRB) assay, comet assay, and Salmonella/microsome assays.

RESULTS

AG-AEL indicated the presence of terpenoids, flavonoids, and phenolic acids. HPLC detected rutin at 2.41 ± 0.33 mg/100 mg. PIXE analysis indicated the presence of Mg, Si, P, S, K, Ca, Mn, and Zn. The 50% inhibitory concentration was 84.17 ± 3.17 μg/mL in the DPPH assay. Genotoxic effects were observed using the Comet assay in neuroblastoma (SH-SY5Y) cells and mutations were observed in TA102 and TA97a strains. The extract showed cytotoxic activities against ovarian (OVCAR-3), glioblastoma (U87MG), and colon (HT-29) cancer cell lines.

CONCLUSIONS

In conclusion, AG-AEL increased DNA damage, induced frameshift, and oxidative mutations, and showed cytotoxic activities against different cancer cells. The in vitro toxicological effects observed suggest that this plant preparation should be used with caution, despite its pharmacological potential.

Exposure in the tobacco fields: Genetic damage and oxidative stress in tobacco farmers occupationally exposed during harvest and grading seasons

Agricultural workers engaged in tobacco cultivation are constantly exposed to large amounts of harmful agents, such as pesticides and nicotine. Furthermore, most of the flue-cured tobacco leaves are manually graded exposing workers to agents such as tobacco-specific nitrosamines. This study aimed to evaluate genetic damage and oxidative stress in tobacco farmers occupationally exposed during the harvest and grading seasons. We obtained data on DNA damage detected in Comet assay in blood cells and micronucleus experiment with buccal cells from 241 individuals. The serum cotinine levels and nitrates were also evaluated. The Comet Assay results showed a showed an increased visual score for males and females during harvest time and tobacco grading. An increase of micronucleated and binucleated cells was observed in the grading group compared to the control and harvest groups. The oxidative stress measurements showed a clear increase of thiobarbituric acid reactive substances (TBARS) in tobacco farmers during harvest time, and trolox equivalent antioxidant capacity (TEAC) in individuals during harvest and grading time compared to the controls. Significant increases of the cotinine levels were observed during the harvest and grading period (harvest>grading), and nitrates for the grading period compared to the control. In this study, tobacco farmers presented compromised DNA integrity associated with enhanced oxidative stress levels.

In vitro genotoxic and mutagenic effects of water samples from Sapucaia and Esteio streams (Brazil) under the influence of different anthropogenic activities

Pollution of aquatic ecosystems is associated with the discharge of mainly industrial and urban effluents, which may cause damage to public health. This study aims to evaluate the cytotoxic, genotoxic, and mutagenic potential of surface water samples under the influence of different anthropogenic effluents in a human-derived liver cell line (HepG2). Samples were collected in Esteio and Sapucaia streams (Rio Grande do Sul; Brazil), which flow into the Sinos River, a source of water supply for more than one million people. Physicochemical and microbiological analyses were performed as well as an analysis of inorganic elements using the PIXE technique (Particle-Induced X-Ray Emission). The presence of pharmaceutical compounds and caffeine was evaluated by gas chromatography coupled to mass spectrometry. The cytotoxicity, genotoxicity, and mutagenicity of the samples were evaluated in HepG2 cells by cell viability assays, alkaline Comet Assay and Cytokinesis-block micronucleus (CBMN) assay. We verified alterations in the physicochemical and microbiological parameters and detected caffeine, diethyltoluamide, and different inorganic elements that corresponded to elements from domestic and industrial effluents and agricultural runoff. Although the samples in the concentration used were not cytotoxic, water samples from all sites induced DNA damage. However, it is difficult to attribute these damages to a specific substance since the factors are a complex mixture of different compounds. Despite this, it is observed that both urban and industrial contributions had a similar effect in the cells evaluated. Such results demonstrate the need to perform biomonitoring of surface waters under anthropogenic influence, especially those that flow into rivers that are a source of public supply water. We also highlight the need for research into emerging pollutants in these aquatic environments.

Environmental exposure to mineral coal and by-products: Influence on human health and genomic instability

Environmental exposure to pollution generated by mining and burning coal is inevitable for people living nearby. Therefore, the aim of this study was to evaluate the influence of coal dust on health conditions and genomic instability of individuals who live near coal mines and thermoelectric power plants, and to relate the results to inorganic elements and inflammatory responses. Thus, we evaluated 284 individuals from four cities in the south of Brazil around a region with coal mines and a thermoelectric power plant (one city was considered a negative control). The results of the Comet assay and Micronucleus (MN) test did not show a genotoxic or mutagenic effect related to environmental exposure to coal, but the inflammatory cytokine tumor necrosis factor-α (TNF-α) was increased in all cities around the power plant when compared to the control conditions. Higher levels of MN were associated with body mass index and cardiovascular risk, and higher levels of Damage Index (DI), TNF-α and interleukin1β (IL-1β) with number of cigarettes/day. Principal component analysis (PCA) was used to integrate DNA damage and inflammatory results with inorganic elements. This study also demonstrated the relationship between zinc and MN, copper, and interleukin10 (IL-10), and among silicon and sulfur with DI and nucleoplasmic bridge. A relationship was also observed between the reduction of inorganic elements and both aging and quality of health. The use of different methodologies and the relationship between the results obtained in these studies, including different lifestyles, can increase the understanding of the interaction between this mineral and the health status of residents of regions affected by coal pollution.

Genotoxic effect induced by dried nicotiana tabacum leaves from tobacco barns (kiln-houses) in chinese hamster lung fibroblast cells (V79)

Nicotiana tabacum is the most cultivated tobacco species in the state of Rio Grande do Sul, Brazil. Workers who handle the plant are exposed to the leaf components during the harvesting process and when separating and classifying the dried leaves. In addition to nicotine, after the drying process, other components may be found including tobacco-specific nitrosamines, polycyclic aromatic hydrocarbons, as well as pesticides residues. The objective of this study was to examine the genotoxicity attributed to the aqueous extract of dried tobacco leaves obtained from tobacco barns using Chinese hamster lung fibroblast cells (V79) as a model system by employing alkaline comet assay, micronucleus (MN) and Ames test. MTT assay was used to assess cytotoxicity and establish concentrations for this study. Data demonstrated cell viability > 85% for concentrations of 0.625-5 mg/ml while the comet assay indicated a significant increase in DNA damage at all concentrations tested. A significant elevation of MN and nuclear buds (NBUD) was found for 5 mg/ml compared to control and other dry tobacco leaves concentrations (0.625-2.5 mg/ml). Mutagenicity was not found using the Salmonella/Microsome test (TA98, TA100, and TA102 strains) with and without metabolic activation. The concentration of inorganic elements was determined employing the PIXE technique, and 13 inorganic elements were detected. Using CG/MS nicotine amounts present were 1.56 mg/g dry tobacco leaf powder. Due to the observed genotoxicity in V79 cells, more investigations are needed to protect the health of tobacco workers exposed daily to this complex mixture of toxic substances present in dry tobacco leaves.

Evaluation of soils under the influence of coal mining and a thermoelectric plant in the city of Candiota and vicinity, Brazil

Coal burning generates gases, particles, and condensation by-products that are harmful to soil, water, and to the atmosphere. The aim of this study was to characterize and identify the cytotoxic and mutagenic potential of soil samples from the cities of Aceguá, Bagé, Candiota and Pinheiro Machado, near a large coal-fired power plant. Our study describes soil characteristics and contributes to the evaluation of the genotoxic activity of coal mining and burning, using the Comet Assay and Micronucleus test in V79 cells, as well as mutagenicity assays with Salmonella typhimurium strains. Comet Assay results show that the winter soil samples of Candiota and Pinheiro Machado induced a significant increase of the Damage Index for cells, as well as for the Aceguá summer sample. The micronucleus test did not detect differences between cities and seasons. A component analysis indicates associations between results obtained in Comet Assay and Ti and phenanthene concentrations for Pinheiro Machado during the winter, and Al for Aceguá during the summer and Zn during the winter. Results of Salmonella/microsome assays were negative, only Candiota and Pinheiro Machado samples showed a statistical increase of his + colonies in TA102. Our work describes biological data on these cells exposed to coal-contaminated soil, confirming the sensitivity of the Comet Assay in V79 cells and Salmonella/microsome assay for the evaluation of the effects of complex mixtures. These findings help to understand the spatial distribution of contaminants in the local soil related to a power plant, which is important for planning public safety actions.

Evaluation of the mutagenicity and genotoxicity of Arrabidaea chica Verlot (Bignoneaceae), an Amazon plant with medicinal properties

Arrabidaea chica Verlot (Bignoniaceae) is an important folk medicine plant native to the Amazon region and used to treat anemia, hemorrhage, inflammation, intestinal colic, hepatitis, and skin affections. Although studies showed its therapeutic properties, little knowledge regarding genotoxic properties of this plant is available. The aim of this study was to determine the potential mutagenic and genotoxic/antigenotoxic effects of an A. chica chloroformic fraction (Ac-CF) obtained from leaves containing bioactive metabolites. The mutagenic effects were evaluated using the Salmonella mutagenicity assay, with TA98, TA97a, TA100, TA102, and TA1535 strains, with and without metabolic activation. In vivo mutagenic and genotoxic/antigenotoxic effects were investigated using the micronucleus (MN) test in bone marrow and alkaline comet assay in blood and liver after administration of 100, 500, or 1000 mg/kg Ac-CF in CF-1 mice by gavage (once a day for 3 d). In vitro antioxidant potential was evaluated using DPPH and xanthine/hypoxanthine assays. Ac-CF was not mutagenic in any of the Salmonella typhimurium strains tested and showed negative responses for mutagenicity and genotoxicity in mice. Further, Ac-CF displayed antigenotoxic effects by decreasing the oxidative DNA damage induced by hydrogen peroxide by greater than 50% in blood and liver. The antioxidant action detected in the in vitro assays demonstrated IC50 of 0.838 mg/ml in the xanthine/hypoxanthine assay and IC50 of 28.17 μg/ml in the DPPH assay. In conclusion, Ac-CF did not induce mutagenic and genotoxic effects and was able to protect DNA against oxidative damage in vivo, suggesting that this fraction may not pose genetic risks, although further toxicology assays are necessary.