Evaluation of genetic damage in Brazilian footwear-workers: Biomarkers of exposure, effect, and susceptibility

The role of genetic polymorphisms for inducing genotoxicity in workers occupationally exposed to benzene: a systematic review

Benzene is used worldwide as a major raw material in a number of industrial processes and also a potent airborne pollutant emitted from traffic exhaust fume. The present systematic review aimed to identify potential associations between genetic polymorphisms and occupational benzene-induced genotoxicity. For this purpose, a total of 22 selected studies were carefully analysed. Our results revealed a positive relation between gene polymorphism and genotoxicity in individuals exposed to benzene, since 17 studies (out of 22) observed positive relations between genotoxicity and polymorphisms in xenobiotics metabolizing genes influencing, therefore, individuals' susceptibility to genomic damage induced by benzene. In other words, individuals with some genotypes may show increase or decrease DNA damage and/or higher or lower DNA-repair potential. As for the quality assessment, 17 studies (out of 22) were categorized as Strong or Moderate and, therefore, we consider our findings to be trustworthy. Taken together, such findings are consistent with the notion that benzene induces genotoxicity in mammalian cells being strongly dependent on the genetic polymorphism. Certainly, such findings are important for clarifying the role of biomarkers related to genotoxicity in human biomonitoring studies.

The Comet Assay as a Tool in Human Biomonitoring Studies of Environmental and Occupational Exposure to Chemicals-A Systematic Scoping Review

Biomonitoring of human populations exposed to chemical substances that can act as potential mutagens or carcinogens, may enable the detection of damage and early disease prevention. In recent years, the comet assay has become an important tool for assessing DNA damage, both in environmental and occupational exposure contexts. To evidence the role of the comet assay in human biomonitoring, we have analysed original research studies of environmental or occupational exposure that used the comet assay in their assessments, following the PRISMA-ScR method (preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews). Groups of chemicals were designated according to a broad classification, and the results obtained from over 300 original studies (n = 123 on air pollutants, n = 14 on anaesthetics, n = 18 on antineoplastic drugs, n = 57 on heavy metals, n = 59 on pesticides, and n = 49 on solvents) showed overall higher values of DNA strand breaks in the exposed subjects in comparison with the unexposed. In summary, our systematic scoping review strengthens the relevance of the use of the comet assay in assessing DNA damage in human biomonitoring studies.

Association of glutathione-S-transferase polymorphism with genetic damage in paint workers

BACKGROUND

Occupational exposure to toluene causes serious health problems ranging from drowsiness to lethal diseases such as cancer. Paint workers are exposed to toluene through inhalation or the dermal route, which can induce genetcic damage. The increased DNA damage could be linked to genetic polymorphism. Therefore, we evaluated the association of glutathione-S-transferase polymorphism with DNA damage in paint workers.

METHODS

First, we included skilled paint workers (n = 30) as exposed and healthy individuals (n = 30) as control belonging to the same socio-economic strata. The genotoxicity biomarkers, Cytokinesis-block micronucleus (CBMN), and single-cell gel electrophoresis (SCGE)/Comet assay were used to assess genotoxicity while Multiplex-PCR and PCR-RFLP were used to assess polymorphism in glutathione-s-transferase (GST) genes. Using linear curve regression analysis, we assessed the association between genetic damage and polymorphism in the glutathione-s-transferase (GST) gene in the exposed and control subjects.

RESULTS

A significantly higher frequency of CBMN (4.43 ± 1.50) and tail moment (TM) (11.23 ± 1.0) respectively in paint workers as compared to the control(1.50 ± 0.86 and (0.54 ± 0.37) underlined significantly high genetic damage in paint workers.Regression curve analysis reveals that polymorphism in the GST gene is significantly associated with higher MN and TM in paint workers.

CONCLUSION

Overall, our study provides a strong rationale for identifying a clear association between glutathione-S-transferase polymorphism and genetic damage in paint workers.

[Cancer risk evaluation in individuals occupationally exposed to organic solvents]

OBJECTIVE

To evaluate the frequency of micronuclei (MNs) and influence of GSTM1 and GSTT1 gene polymorphisms as biomarkers of cancer risk in car painters (n=152) compared to unexposed individuals (n=152).

METHODS

Molecular epidemiology study, cross-sectional analysis of gen and environment interaction. The evaluation of MN and genetic polymorphisms was determined by molecular tests in lymphocytes from subjects involved in the study.

RESULTS

It was determined that the frequency of MNs is 1.6 higher in the exposed group compared to the reference group (1.39 ± 0.92 versus 0.87 ± 0.78, p<0.0001). There was no increase in the frequency of MNs associated with the polymorphisms in GSTM1 and GSTT1.

CONCLUSIONS

The increase of MNs in car painters serves to alert the increased risk of cancer in this population exposed to organic solvents. These results can be used in Occupational Epidemiological Surveillance Programs, as a prevention strategy and policies to regulate and control the use of solvents at a national level and in other countries with a large informal sector of individuals exposed to these chemicals to reduce the risk of cancer.

Effect of Pesticide Exposure over DNA Damage in Farmers from Los Reyes, Michoacan in Mexico

In the municipality of Los Reyes, Michoacán, in Mexico, several economic activities coexist; however, the most relevant is agriculture. It stands out as an agro-industrial center and commercial enclave in the region, suitable for the cultivation of sugar cane; however, currently fruit growing takes first place with blackberry, raspberry and blueberry, followed by avocado, peach, strawberry and other crops. A large quantity and variety of pesticides are applied to crops, consequently the population is at constant risk. This study aimed to evaluate whether pesticides are a factor in genetic damage to agricultural workers from Los Reyes, Michoacán, using alkaline comet assay. Fifty-nine residents participated (41 workers and 18 controls). Results included confounding factors (alcohol consumption, smoking habit, gender, age, BMI, etc.) indicated a non-significant statistical difference between two groups, with higher DNA damage values in workers that was higher than the values expected in a normal healthy unexposed population. It seems that the control measures, safe handling of pesticides and quality standards, required by the producers so that their products can be exported, have resulted in less damage, despite workers' activity, but higher damage than the reference values still requires regular surveillance of those exposed. The use of protective equipment or measures can reduce the risk of damage, so it is also necessary to promote their service and comply with labor regulations for agricultural workers.

Brazilian workers occupationally exposed to different toxic agents: A systematic review on DNA damage

The evaluation of genotoxicity in workers exposed to different toxic agents is very important, especially considering the association between these exposures in a chronic context and DNA damage. Assessing biomarkers of exposure and, when possible, early biomarkers of effect, contributes to elucidating the potential toxic mechanisms involved in genotoxicity and its contribution to chronic non-communicable diseases. In Brazil, the biggest country in South America, workers are exposed to hazardous physical and chemical agents. Considering that these exposures occur, in most cases, throughout the worker's whole life, this is an important public health concern in Brazil. Therefore, this systematic review aims to analyze occupational exposure to chemical and physical agents and the association with DNA damage in studies carried out in Brazil from 1980 to 2021. A systematic and comprehensive literature search was performed in different databases based on occupational exposure to chemical and physical agents and DNA damage. Only full articles on studies that investigated experimental evidence on occupational exposure in Brazil and assessed DNA damage were included, amounting to 89 articles. Five main occupational exposure groups were identified: pesticides (36%), organic solvents (20%), dust and particles (16%), metals (11%), and ionizing radiation (6%). Another group called "others" included studies (11%) that did not fall into these main groups. It was found that comet assay and micronucleus tests are the most adopted methods to detect DNA damage. Occupational exposures were most associated with DNA damage. However, further improvements in study design would be needed to better characterize the association between biomonitoring and DNA damage, particularly to account for confounding factors.

Occupational health hazards and wide spectrum of genetic damage by the organic solvent fumes at the workplace: A critical appraisal

Long-term exposure to organic solvents is known to affect human health posing serious occupational hazards. Organic solvents are genotoxic, and they can cause genetic changes in the exposed employees' somatic or germ cells. Chemicals such as benzene, toluene, and gasoline induce an excessive amount of genotoxicity results either in genetic polymorphism or culminates in deleterious mutations when concentration crosses the threshold limits. The impact of genotoxicity is directly related to the time of exposure, types, and quantum of solvent. Genotoxicity affects almost all the physiological systems, but the most vulnerable ones are the nervous system, reproductive system, and blood circulatory system. Based on the available literature report, we propose to evaluate the outcomes of such chemicals on the exposed humans at the workplace. Attempts would be made to ascertain if the long-term exposure makes a person resistant to such chemicals. This may seem to be a far-fetched idea but has not been studied. The health prospect of this study is envisaged to complement the already existing data facilitating a deeper understanding of the genotoxicity across the population. This would also demonstrate if it correlates with the demographic profile of the population and contributes to comorbidity and epidemiology.

Development of a biomarker database toward performing disease classification and finding disease interrelations

A biomarker is a measurable indicator of a disease or abnormal state of a body that plays an important role in disease diagnosis, prognosis and treatment. The biomarker has become a significant topic due to its versatile usage in the medical field and in rapid detection of the presence or severity of some diseases. The volume of biomarker data is rapidly increasing and the identified data are scattered. To provide comprehensive information, the explosively growing data need to be recorded in a single platform. There is no open-source freely available comprehensive online biomarker database. To fulfill this purpose, we have developed a human biomarker database as part of the KNApSAcK family databases which contain a vast quantity of information on the relationships between biomarkers and diseases. We have classified the diseases into 18 disease classes, mostly according to the National Center for Biotechnology Information definitions. Apart from this database development, we also have performed disease classification by separately using protein and metabolite biomarkers based on the network clustering algorithm DPClusO and hierarchical clustering. Finally, we reached a conclusion about the relationships among the disease classes. The human biomarker database can be accessed online and the inter-disease relationships may be helpful in understanding the molecular mechanisms of diseases. To our knowledge, this is one of the first approaches to classify diseases based on biomarkers. Database URL:  http://www.knapsackfamily.com/Biomarker/top.php.

Impact of rapeseed pomace extract on markers of oxidative stress and DNA damage in human SH-SY5Y cells

With increased longevity and subsequent rise in people with age-related neurodegenerative diseases, protection of neurons from oxidative stress damage has become an important field of study. For the first time, we highlight the neuroprotective properties of rapeseed pomace (RSP) extract in SH-SY5Y human neuroblastoma cells. We used resazurin to determine cell metabolism, 2,7'-dichlorofluorescin diacetate (H₂ DCFDA) to assess the potential of RSP extracts to shield cells from reactive oxygen species (ROS) induced by H₂ O₂ using flow cytometry, HPLC to analyze for malondialdehyde (MDA) as a lipid peroxidation marker and the COMET assay to assess DNA strand breakage. Protein stress arrays were used to investigate the cellular pathways affected by RSP extract. No effect on cell metabolism in SH-SY5Y cells was observed after RSP extract treatment (up to 1.5 mg/ml). Pretreatment (24 hr) with RSP extract (1 mg/ml), before H₂ O₂ -induced stress, alleviated ROS production and DNA strand breakage by 68%, and 38%, respectively. At protein level, the RSP extract increased the levels of FABP-1, HIF-1α, SOD2, and Cytochrome c proteins. Under H₂ O₂ -induced stress, however, it helped to downregulate p38α levels, a protein kinase which is receptive to stress impulse (mitogen-activated). RSP extract shows very promising cell protective properties in relation to oxidative stress. PRACTICAL APPLICATIONS: Oxidative stress has been associated with numerous diseases for example cancer, diabetes, and many neurological disorders including Parkinson's and Alzheimer's diseases. Hence, there is acceptance among the scientific community of antioxidant therapy and the quest for effective, low cost and readily available sources of natural antioxidants is paramount. Rapeseed plantations are abundant around the world due to the use of rapeseed oil in cooking and as a biofuel. The resulting rapeseed pomace (by-product), specifically its extract, contains high levels of phytochemicals that protect cells against oxidative stress. Therefore, RSP extract can potentially be used/developed as functional food and nutraceuticals in the prevention of many complex neurodegenerative diseases.

Impact of nicotine-induced green tobacco sickness on DNA damage and the relation with symptoms and alterations of redox status in tobacco farmers

During the harvest period, tobacco workers are exposed to nicotine and it is known that absorption of the alkaloid via the leaves causes green tobacco sickness (GST). We investigated if GST and its symptoms are associated with DNA damage and alterations of the redox status. DNA damage was measured in lymphocytes of tobacco workers and controls (n = 40/group) in single cell gel electrophoresis assays. Exposure to nicotine was determined by plasma cotinine measurements, alterations of the redox status by quantification of the total antioxidant capacity (TEAC) and of thiobarbituric acid reactive substances (TBARS). The symptoms of GTS included nausea, abdominal cramps, headache, vomiting and dizziness, and 50% of the workers had more than one symptom. Cotinine levels were enhanced in the workers (111 ng/mL); furthermore, the extent of DNA damage was ca. 3-fold higher than in the controls. This effect was more pronounced in participants with GST compared to healthy nicotine exposed workers and increased in individuals with specific symptoms (range 22-36%). TBARS levels did not differ between workers and unexposed controls, while TEAC values were even increased (by 14.3%). Contact with nicotine present in tobacco leaves causes GTS and leads to damage of the DNA; this effect is more pronounced in workers with GTS symptoms and is associated with alterations of the redox status. Damage of the genetic material which was found in the workers may lead to adverse long-term effects that are caused by genomic instability such as cancer and accelerated ageing.

Toxicological responses of BEAS-2B cells to repeated exposures to benzene, toluene, m-xylene, and mesitylene using air-liquid interface method

In order to reduce exposure to toxic chemicals, the European REACH regulation (1907/2006) recommends substituting toxic molecules with compounds that are less harmful to human health and the environment. Toluene is one of the most frequently used solvents in industries despite its toxicity. The objective of this study is to better understand and compare the toxicity of toluene and its homologues in a bronchial cell model. Thus, human bronchial BEAS-2B cells were exposed to steams of toluene, m-xylene, mesitylene (1,3,5-trimethylbenzene), and benzene (20 and 100 ppm). Exposure was carried out using an air-liquid interface (ALI) system (Vitrocell) during 1 h/day for 1, 3, or 5 days. Cytotoxicity, xenobiotic metabolism enzyme gene expression, and inflammatory response were evaluated following cell exposures. BEAS-2B cell exposure to toluene and its homologues revealed the involvement of major (CYP2E1) and minor metabolic pathways (CYP1A1). A late induction of genes (EPHX1, DHDH, ALDH2, and ALDH3B1) was measured from Day 3 and can be linked to the formation of metabolites. An increase in the secretion level of inflammatory markers (TNF-α, IL-6, IL-8, MCP-1, and GM-CSF) was also observed. In parallel, regulation between inflammatory mediators and the expression of transmembrane glycoprotein mucin MUC1 was also studied. This in vitro approach with ALI system points out the relevance of conducting repeated exposures to detect potential late effects. The difference recorded after cell exposure to toluene and its homologues highlights the importance of substitution principle.

Buccal micronucleus cytome assay: Inter-laboratory scoring exercise and micronucleus and nuclear abnormalities frequencies in different populations from Brazil

The Buccal Micronucleus Cytome Assay (BMCyt) has become an important biomonitoring tool for assessing cytogenetic damage in many studied populations. Each laboratory applies protocols that vary according to the method of collecting and preparing samples. Besides, Brazil is a country of great territorial extensions that received immigrants from various parts of the world with different genetic backgrounds. Therefore, the present study aimed to evaluate the inter-laboratory variation in scoring the same set of slides using the more comprehensive scoring criteria, to standardize the BMCyt protocol, to observe the basal alterations in populations of different Brazilian regions and to compare it with other places around the world. Our results showed that a valuable number of laboratories participated, ten laboratories from different regions of the country, for the validation of the BMCyt in human biomonitoring studies, resulting in the 804 healthy individuals. This was possible because we observed: a range of measures needs to be considered, such as the baseline frequency of DNA damage and cell death in non-exposed individuals; age when grouped showed an influence on DNA damage, although when evaluated by group we did not see an influence; association between smoking habit and all endpoints of the BMCyt (except karyolytic cells) was evident; the basal MN frequency, in the majority of groups, follows those around the world; and the BMCyt was confirmed as a good health status biomarker. We emphasize the need for constant discussions on the parameters of cell death due to greater difficulty among the analyzers.

Biomarkers of susceptibility and effect in car painters exposed to organic solvents

Introduction

Car painters are routinely exposed to organic solvents classified as carcinogenic and mutagenic substances.

Objective

To characterize the population susceptibility and evaluate the genotoxic effects of exposure to organic solvents.

Methods

A cross-sectional study comparing a group of car painters exposed to organic solvents with a non-exposed group. CYP2E1 polymorphisms and the presence of micronuclei in lymphocytes were determined.

Results

One hundred twenty-two workers participated in the study: 62 who worked in car paint shops and were exposed to solvents, and 60 who were not exposed. There were statistically significant differences between the two groups regarding micronucleated cells and nucleoplasmic bridges frequencies (p= 0.042 and p= 0.046, respectively; exact likelihood ratio). Significant differences were found at the interaction between the CYP2E1 genotype c1c1 and occupational exposure to solvents, with higher frequencies of micronuclei (p= 0.013) and micronucleated cells (p= 0.015). However, when the frequencies of micronuclei, micronucleated cells and nucleoplasmic bridges in the exposure group were compared between the c1c1 and c2c2/c1c2 allele groups of the CYP2E1 polymorphism, statistically significant differences were found.

Conclusions

This study confirms that when workers with CYP2E1 polymorphisms, specifically the c1c1 genotype, are exposed to organic solvents, they are more likely to have somatic cell mutations, a condition associated with increased susceptibility to diseases such as cancer.

The influence of polymorphisms of xenobiotic-metabolizing and DNA repair genes in DNA damage, telomere length and global DNA methylation evaluated in open-cast coal mining workers

Coal plants represent one of the main sources of environmental pollution due to the combustion process of this mineral and the consequent release of gases and particles which, in significant quantities, can lead to a potential risk to health and the environment. The susceptibility of individuals to the genotoxic effects of coal mining can be modulated by genetic variations in the xenobiotic detoxification and DNA repair processes. The aim of this study was to evaluate if xenobiotic metabolism polymorphism, base excision repair polymorphisms and non-homologous end joining repair polymorphism, could modify individual susceptibility to genomic instability and epigenetic alterations induced in workers by occupational exposure to coal. In this study, polymerase chain reaction was used to examine the polymorphic sites. The sample population comprising 70 coal mine workers and 71 workers non-exposed to coal. Our results demonstrated the effect of individual genotypes on different biomarkers evaluated. Significant decrease in % of global DNA methylation were observed in CYP1A1 Val/- exposed individuals compared to CYP1A1 Ile/Ile individuals. Coal workers who carried the XRCC4 Ile/Ile genotype showed decrease NBUD frequencies, while the XRCC4 Thr/- genotype was associated with decrease in Buccal micronucleus cells for the group not exposed. No influence of GSTM1 null, GSTT1 null, GSTP1 Ile105Val, hOGG1 Ser326Cys, XRCC1 Arg194Trp polymorphisms was observed. Thus, the current study reinforces the importance of considering the effect of metabolizing and repair variant genotypes on the individual susceptibility to incorporate DNA damage, as these processes act in a coordinated manner to determine the final response to coal exposure.

Evaluation of oxidative and methylating DNA damage in painters occupationally exposed to organic solvents and paints

Introduction: The exposure to organic solvents and paints has been associated with genotoxicity and a greater risk of neoplasms. However, the type of DNA damage induced in humans by the exposure to these compounds, which would help explain the mechanisms of their genotoxicity, is still not fully characterized. Due to inadequate practices of occupational safety, car painters in the informal sector are a highly exposed group to organic solvents and paints. Objective: To identify the oxidative and methylating damage in the DNA of lymphocytes of car painters exposed to organic solvents and paints. Materials and methods: Isolated peripheral blood lymphocytes from 62 painters and 62 unexposed subjects were analyzed by the modified high-throughput comet assay with the Fpg and AlkA enzymes. The categories used for the evaluation of the DNA damage were basal damage (without enzymes), oxidative and methylating damage. The measurement parameter used to establish the damage was the percentage of DNA in the tail. Results: The percentage of DNA in the tail was higher in the exposed group compared to the unexposed group (p<0.05). In the exposed group, this percentage was higher in the oxidative damage category than the baseline (16.50 vs. 12.87; p<0.001), whereas methylating damage did not show significant differences (14.00 vs. 12.87; p>0.05). Conclusion: In this study, exposure to organic solvents and paints was associated with an increase in oxidative lesions in the DNA of car painters’ lymphocytes, such as the production of 8-oxodG and other formamidopyrimidine products which are considered highly mutagenic.

Acute and Chronic Exposure of Toluene Induces Genotoxicity in Different Regions of the Brain in Normal and Allergic Mouse Models

Toluene is a widely used industrial organic solvent and is ubiquitous in our environment. The neurobehavioral and neurotoxic effects of toluene are well recognized; however, its genotoxicity is still under discussion. Toluene biotransformation leads to the generation of reactive oxygen species that cause oxidative stress and DNA damages. Individuals with different immunogenetic backgrounds have different sensitivities to toxic chemical exposure. Previous studies have suggested that allergic stimulation may influence the threshold for toluene sensitivity due to the modulation of neurotrophin-related genes. Therefore, we aimed to investigate toluene-induced genotoxicity in different brain regions following acute and chronic exposure in vivo and to further examine whether allergic stimulation may influence the sensitivity to toluene-induced genotoxicity. In this present study, we found that exposure of toluene induced oxidative DNA damages resulting in genotoxicity in different brain regions including cortex, cerebellum, and hippocampus using comet assay. Higher genotoxicity induced by toluene was observed in the hippocampus of control mice compared to OVA-immunized mice. These results provide evidence that toluene-induced genotoxicity may contribute to its neurotoxicity in different immunogenetic individuals.

Genotoxicity of inhalational anesthetics and its relationship with the polymorphisms of GSTT1, GSTM1, and GSTP1 genes

Due to their wide applications, concern exists regarding possible genotoxic effects of inhalational anesthetics (IAs) among operating room personnel. This study was undertaken to examine genotoxic properties of co-exposure to nitrous oxide, sevoflurane, and isoflurane on induction of micronucleus (MN) and chromosomal aberrations (CAs) and to determine whether any associations exist between polymorphisms of GST genes and the level of genomic damage measured by MN and CAs assays. Sixty operating room personnel and 60 unexposed referent nurses were studied. The workers' exposure to the IAs was determined. DNA damage was evaluated by MN and CAs assays. Additionally, the GSTM1, GSTT1, and GSTP1 polymorphisms were detected. The mean concentrations of nitrous oxide, isoflurane, and sevoflurane were found to be 850.92 ± 919.78, 2.40 ± 0.86, and 0.18 ± 0.14 ppm, respectively. The frequency of MN and CAs in the exposed group was significantly higher than that of the non-exposed group. The frequency of MN was significantly higher in referent nurses with null GSTT1, compared to referent nurses with positive GSTT1. The frequency of MN was significantly higher in exposed individuals carrying the combined genotype of GSTT1 (-), GSTM1 (-), and GSTP1 AG as compared with subjects carrying a combination of GSTT1 (+), GSTM1 (+), and GSTP1 AA. Statistically significant associations were noted between exposure to the IAs, gender, and the combination of the three GSTs genotypes with MN frequency. These findings indicate that inhalation exposure to IAs induces genotoxic response and the polymorphisms of GSTs genes might modulate the effect of exposure to IAs on MN.

Evaluation of the exposure to coal dust and prevalence of pneumoconiosis in underground mining in three Colombian departments

Introduction: Coal workers’ pneumoconiosis is a chronic and irreversible disease representing a public health problem. Objective: To estimate the prevalence of pneumoconiosis and its associated factors among underground coal miners in the Colombian departments of Boyacá, Cundinamarca and Norte de Santander. Materials and methods: We conducted a cross-sectional study of 476 miners to measure the prevalence of pneumoconiosis and its associated factors such as coal dust and silica levels, as well as the occupational conditions. The medical assessment and a chest x-ray were performed according to the International Labor Organization criteria, along with spirometry and the identification of glutathione S-transferase and repair enzyme polymorphisms.The associations were explored using Cox regression models. Results: We performed a total of 479 environmental monitoring sessions in 31 companies and we evaluated 476 workers with 10 to 57 years of mining work experience. The prevalence of pneumoconiosis was 33.8% (95% CI: 27.0 - 41.3%). In the Cox multivariate regression model with a constant risk time, pneumoconiosis was significantly associated with working in medium-sized companies (PR=2.00, 95% CI: 0.995 - 2.690; p=0.052), the level of severe exposure to coal dust (PR=2.055, 95% CI: 1.043 - 4.048; p=0.038), and working in underground mining for 25 years or more (for those with 25.0-29.9 years: PR=2.199, 95% CI: 1.449 - 3.338; p=0.001). Conclusions: The prevalence of pneumoconiosis was very high and was found to be associated with severe exposure to coal dust, work exposure for 25 years or more and working in medium-sized enterprises

Base excision repair (OGG1 and XRCC1) and metabolism (PON1) gene polymorphisms act on modulation of DNA damage and immune parameters in tobacco farmers

Pesticides are one of the most frequently investigated chemical, due to their multiple uses in agricultural and public health areas. This study evaluates lymphocytes CBMN (cytokinesis-block micronucleus cytome assay), inflammatory markers, inorganic elements in blood samples, and the relationship of these parameters with XRCC1Arg194Trp, OGG1Ser326Cys and PON1Gln192Arg polymorphisms in a population of tobacco farmers. The study population comprised 129 agricultural workers exposed to pesticides and 91 nonexposed. Farmers had significantly increased NPB (nuclear plasmatic bridge), MN (micronucleus) and NBUD (nuclear bud) frequencies, as well as IL-6 (interleukin 6) and TNF-α (tumor necrosis factor alpha) serum levels, and decreased cytokines CD4+/CD8+ ratio. In the exposed group, XRCC1 Trp/- was correlated with decreased NDI (nuclear division index), and OGG1 Cys/- was associated with higher levels of NPB and decreased levels of IL-6. The combined effects of PON1 Arg/- and XRCC1 Arg/Arg were associated with increased NPB frequencies. In addition, the combination of PON1 Arg/- with XRCC1 Trp/- or OGG1 Cys/- influenced in increased levels of necrosis in farmers. Furthermore, tobacco farmers showed a positive correlation between TNF-α levels and NPB, CD4+/CD8+ ratio and NBUD; and IL-6 levels with both MN and NDI. The duration of years of work at tobacco fields was correlated positively with NBUD frequency. Sulfur, chlorine and potassium were found at increased levels in the exposed group when compared to the nonexposed one. These findings provide evidence that tobacco farmers' exposure have increased DNA damage and alter the immune system's response, and that XRCC1 and OGG1 polymorphisms could influence both biomarkers results.

Cytogenetic surveillance of persons occupationally exposed to genotoxic chemicals

Human genotoxic exposures can occur environmentally, occupationally, or medicinally. The aim of this study was to assess cytogenetic damage (chromosomal aberrations and micronuclei) in persons exposed to chemical agents in medical, agricultural, and industrial occupations. The results showed influences of age, gender, occurrence, and duration of exposure on the extent of cytogenetic damage, but no influence of smoking. Persons exposed to pesticides were allocated significantly higher values of most examined parameters. Among all tested parameters, logistic regression analysis marked tMN, CB, and iCB as the best predictors with high discrimination accuracy of separation between exposed and unexposed persons. The obtained data encourage us to consider certain cytogenetic parameters as valuable markers for preventive medical screening as the extent of cytogenetic damage reflects cumulative exposure events and possible health consequences related to chronic occupational genotoxic exposure.

Assessment of DNA damage in a group of professional dancers during a 10-month dancing season

Despite the numerous health benefits of physical activity, some studies reported that increased intensity and duration may induce oxidative stress in several cellular components including DNA. The aim of this study was to assess the level of basal DNA damage as well as oxidative DNA damage in a group of professional dancers before and after a 10-month dancing season. A group of individuals from general population was also assessed as a control. The alkaline version of the comet assay was the method selected to measure both basal DNA damage and oxidative stress, since this method quantifies both endpoints. In order to measure oxidative stress, the comet assay was coupled with a lesion-specific endonuclease (formamidopyrimidine glycosylase) to detect oxidized purines. The levels of oxidative DNA damage in dancers were significantly increased after the dancing season. Pre-season levels of oxidative DNA damage were lower in dancers than those obtained from the general population, suggesting an adaptation of antioxidant system in dancers. Results of the present biomonitoring study indicate the need for more effective measures to protect ballet dancers from potentially occupational health risks related to regular intensive physical exercise.

High chromosomal instability in workers occupationally exposed to solvents and paint removers

BACKGROUND

Painters are exposed to an extensive variety of harmful substances like aromatic hydrocarbons used as solvents and paint removers, some of which have shown clastogenic activity. These substances constitute a complex mixture of chemicals which contain well-known genotoxicants, such as Benzene, Toluene and Xylene. Thus, chronic occupational exposure to such substances may be considered to possess genotoxic risk. In Colombia the information available around the genotoxic damage (Chromosomal and DNA damage) in car paint shop workers is limited and the knowledge of this damage could contribute not only to a better understanding of the carcinogenic effect of this kind of substances but also could be used as biomarkers of occupational exposure to genotoxic agents.

RESULTS

In this study, the genotoxic effect of aromatic hydrocarbons was assessed in peripheral blood lymphocytes of 24 workers occupationally exposed and 24 unexposed donors, by using Cytogenetic analysis and comet assay. A high frequency of Chromosomal alterations was found in the exposed group in comparison with those observed in the unexposed group. Among the total of CAs observed in the exposed group, fragilities were most frequently found (100 %), followed by chromosomal breaks (58 %), structural (41.2 %) and numerical chromosomal alterations (21 %). Numerical chromosomal alterations, fragilities and chromosomal breaks showed significant differences between exposed and unexposed groups. Among the fragilities, fra(9)(q12) was the most frequently observed. DNA damage index was also significantly higher in the exposed group compared to the unexposed group (p < 0.000).

CONCLUSIONS

Our results revealed that occupational exposure to aromatic hydrocarbons is significantly associated with Chromosomal and DNA damage in car paint shops workers and are also indicative of high chromosomal instability. The high frequency of both Chromosomal Alterations and DNA Damage Index observed in this study indicates an urgent need of intervention not only to prevent the increased risk of developing cancer but also to the application of strict health control and motivation to the use of appropriate protecting devices during work.

Investigation of potential biomarkers for the early diagnosis of cellular stability after the exposure of agricultural workers to pesticides

Agricultural workers involved in the harvest of tobacco crops are regularly exposed to large quantities of pesticides. In order to determine how this exposure to pesticides induces genetic alterations in these workers, blood samples were obtained from 77 exposed individuals, as well as from 60 unexposed subjects. DNA damage was analyzed by the Comet assay and by the micronucleus (MN) test. The antioxidant profile was evaluated by activity of superoxide dismutase (SOD), and the polymorphism of gene PON1 was used as a susceptibility biomarker. The content of inorganic elements in the blood samples was determined by PIXE analysis. Our results demonstrated that the damage frequency, damage index, the MN frequency, and the SOD activity were significantly elevated in the exposed relative to the unexposed group. A modulation of the MN results for the PON1 gene was observed in the exposed group. The concentrations of inorganic elements in the exposed group were higher compared to those of the unexposed group. In this study, we observed that genetic damage, and change in oxidative balance were induced by the exposure of workers to complex mixtures of pesticides in the presence of inorganic compounds, whereby an influence of the genotype was evident.

Assessment of ovarian cancer conditions from exhaled breath

We present a pilot study that aims to examine the possibility to easily and noninvasively detect and discriminate females with ovarian cancer (OC) from females that have no tumor(s) and from females that have benign genital tract neoplasia, using exhaled breath samples. The study is based on clinical samples and data from 182 females, as follows: 48 females with OC, 48 tumor-free controls and 86 females with benign gynecological neoplasia. Analysis of the breath samples with gas chromatography linked with mass spectrometry shows that decanal, nonanal, styrene, 2-butanone and hexadecane could serve as potential volatile markers for OC. Analysis of the same samples with tailor-made nanoarrays shows good discrimination between females with OC and females that have either no tumor or benign genital tract neoplasia (71% for accuracy, sensitivity and specificity). Conversely, the nanoarray output shows excellent discrimination between the OC patients and the tumor-free controls (79% sensitivity, 100% specificity and 89% accuracy). These results suggest that the nanoarray approach might be useful to avoid unnecessary complicated or expensive tests for tumor-free females in case of a negative result. In the case of positive result, the test will indicate with high probability the presence of OC.

Genotoxic assessment in tobacco farmers at different crop times

Agricultural workers engaged in tobacco cultivation are constantly exposed to large amounts of pesticides as well as to the nicotine present in raw tobacco leaves. Pesticides have been considered potential chemical mutagens: experimental data revealed that various agrochemicals possess mutagenic properties. Studies have affirmed that nicotine absorbed through the skin results in the characteristic green tobacco sickness (GTS), an occupational illness reported by tobacco workers. This study sought to determine genotoxic effects in farmers occupationally exposed to agrochemicals and nicotine. Peripheral blood samples were collected from 30 agricultural workers, at different crop times (off-season, during pesticides application and leaf harvest), and 30 were non-exposed. We obtained data on DNA damage detected by the Comet assay and Micronucleus test as biomarker of occupational exposure and effect. The serum cholinesterase level, which in general present relation with exposition to organophosphates and carbamates, as well as serum cotinine level, which is a metabolite of nicotine, were also evaluated. The results showed a significant increase in Damage index and frequency in tobacco farmers compared to the non-exposed group, for all different crop times; and a significant increase in micronucleated cells in the off-season group. No correlation was found between age and exposure time in relation to biomarker tests. The DNA damage was greater in males than in females, but with a significant difference only in off-season group. No difference, in cholinesterase activity, was seen among the group of farmers and non-exposed group. Elevated level of cotinine was observed in leaf harvest group. This investigation suggests increased DNA damage in all tobacco crop stages, calling attention to the significant increase during the off-season and tobacco leaf harvest.

Does occupational exposure to solvents and pesticides in association with glutathione S-transferase A1, M1, P1, and T1 polymorphisms increase the risk of bladder cancer? The Belgrade case-control study

OBJECTIVE

We investigated the role of the glutathione S-transferase A1, M1, P1 and T1 gene polymorphisms and potential effect modification by occupational exposure to different chemicals in Serbian bladder cancer male patients.

PATIENTS AND METHODS

A hospital-based case-control study of bladder cancer in men comprised 143 histologically confirmed cases and 114 age-matched male controls. Deletion polymorphism of glutathione S-transferase M1 and T1 was identified by polymerase chain reaction method. Single nucleotide polymorphism of glutathione S-transferase A1 and P1 was identified by restriction fragment length polymorphism method. As a measure of effect size, odds ratio (OR) with corresponding 95% confidence interval (95%CI) was calculated.

RESULTS

The glutathione S-transferase A1, T1 and P1 genotypes did not contribute independently toward the risk of bladder cancer, while the glutathione S-transferase M1-null genotype was overrepresented among cases (OR = 2.1, 95% CI = 1.1-4.2, p = 0.032). The most pronounced effect regarding occupational exposure to solvents and glutathione S-transferase genotype on bladder cancer risk was observed for the low activity glutathione S-transferase A1 genotype (OR = 9.2, 95% CI = 2.4-34.7, p = 0.001). The glutathione S-transferase M1-null genotype also enhanced the risk of bladder cancer among subjects exposed to solvents (OR = 6,5, 95% CI = 2.1-19.7, p = 0.001). The risk of bladder cancer development was 5.3-fold elevated among glutathione S-transferase T1-active patients exposed to solvents in comparison with glutathione S-transferase T1-active unexposed patients (95% CI = 1.9-15.1, p = 0.002). Moreover, men with glutathione S-transferase T1-active genotype exposed to pesticides exhibited 4.5 times higher risk in comparison with unexposed glutathione S-transferase T1-active subjects (95% CI = 0.9-22.5, p = 0.067).

CONCLUSION

Null or low-activity genotypes of the glutathione S-transferase A1, T1, and P1 did not contribute independently towards the risk of bladder cancer in males. However, in association with occupational exposure, low activity glutathione S-transferase A1 and glutathione S-transferase M1-null as well as glutathione S-transferase T1-active genotypes increase individual susceptibility to bladder cancer.

Micronucleus evaluation of exfoliated buccal epithelial cells using liquid-based cytology preparation

OBJECTIVE

Micronuclei (MN) are biomarkers that can be applied to buccal epithelial cells to assess populations occupationally exposed to potentially carcinogenic agents. Liquid-based cytology (LBC) is a way to improve and refine the results obtained by this test.

STUDY DESIGN

Exfoliated buccal cells were collected from 40 subjects (20 construction workers from the Barretos Cancer Hospital and 20 administrative staff from the same institution). LBC and three stains (Feulgen/fast green, Papanicolaou and Giemsa) were used to prepare the slides. Student's t test was applied for statistical comparisons of the data. A p value of <0.05 was considered statistically significant.

RESULTS

Regardless of the stain employed, the frequency of MN was greater in the case group (Feulgen/fast green: 5.15; Papanicolaou: 29; Giemsa: 26) than in the control group (Feulgen/fast green: 2.30; Papanicolaou: 17; Giemsa: 15).

CONCLUSIONS

Using LBC to prepare slides and evaluate the frequency of MN potentially serves as a screening option for more comprehensive studies of cancer risk among populations occupationally exposed to potentially carcinogenic agents. In addition, the residual fluid enables the preparation of slides for DNA-specific stains that can be compared to those with Papanicolaou stain.

Contribution of CYP2E1 polymorphism to aging in the mechanical workshop workers

Aging is attributed to both genetic and environmental factors. Occupational exposure is one of the environmental factors with potential genotoxic effects. Researchers try to determine factors involved in genetic damages at hazards exposure that could accelerate aging. Cytochrome P450 2E1 (CYP2E1) gene contributes in activation and detoxification of the environmental hazards. This polymorphism plays an important role in susceptibility of inter-individuals to DNA damage at the occupational exposure. The current study evaluated the possible influence of this gene polymorphism in aging by genomic damages through the biomarkers alterations of micronuclei (MN), comet tail length and telomere length shortening at the exposure. In this study, buccal cells were collected from the oral cavity of exposed workers and non-exposed controls. The CYP2E1 genotypes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The wild genotype significantly affected MN frequency (p = 0.007) and relative telomere length (p = 0.047) in the older group of workers. It was concluded that the interaction of gene polymorphism and exposure enhances DNA damage and accelerates aging consequently.

Evaluation of DNA damage in COPD patients and its correlation with polymorphisms in repair genes

BACKGROUND

We investigated a potential link between genetic polymorphisms in genes XRCC1 (Arg399Gln), OGG1 (Ser326Cys), XRCC3 (Thr241Met), and XRCC4 (Ile401Thr) with the level of DNA damage and repair, accessed by comet and micronucleus test, in 51 COPD patients and 51 controls.

METHODS

Peripheral blood was used to perform the alkaline and neutral comet assay; and genetic polymorphisms by PCR/RFLP. To assess the susceptibility to exogenous DNA damage, the cells were treated with methyl methanesulphonate for 1-h or 3-h. After 3-h treatment the % residual damage was calculated assuming the value of 1-h treatment as 100%. The cytogenetic damage was evaluated by buccal micronucleus cytome assay (BMCyt).

RESULTS

COPD patients with the risk allele XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) showed higher DNA damage by comet assay. The residual damage was higher for COPD with risk allele in the four genes. In COPD patients was showed negative correlation between BMCyt (binucleated, nuclear bud, condensed chromatin and karyorrhexic cells) with pulmonary function and some variant genotypes.

CONCLUSION

Our results suggest a possible association between variant genotypes in XRCC1 (Arg399Gln), OGG1 (Ser326Cys), XRCC3 (Thr241Met), and XRCC4 (Ile401Thr), DNA damage and progression of COPD.

Toxicogenetic monitoring in urban cities exposed to different airborne contaminants

Microparticles found in the air may be associated with organic matter that contains several compounds, such as Polycyclic Aromatic Hydrocarbons (PAHs) and nitro-PAHs, and may pose a significant risk to human health, possibly leading to DNA mutations and cancers. This study associated genotoxicity assays for evaluating human exposure with the atmospheric air of two urban areas in southern Brazil, that received different atmospheric contributions. Site 1 was under urban-industrial influence and the other was a non-industrial reference, Site 2. Organic extracts from the airborne particulate matter were tested for mutagenicity via the Salmonella/microsome assay and analyzed for PAH composition. Cells samples of people residing in these two cities were evaluated using the comet and micronucleus assay (MN).Concentrations of the individual PAHs ranged from 0.01 ng/m(3) (benzo[a]anthracene) to 5.08 ng/m(3) (benzo[ghi]perylene). As to mutagenicity analysis of airborne, Site 1 presented all the mutagenic responses, which varied from 3.2±1.22 rev/m(3) (TA98 no S9) to 32.6±2.05 rev/m(3) (TA98, S9), while Site 2 ranged from negative to minimal responses. Site 1 presented a high quantity of nitro and amino derivatives of PAHs, and peaked at 56.0±3.68 rev/μg (YG1024 strain). The two groups presented very low DNA damage levels without intergroup difference. Although Site 1 presented high mutagenic responses in the air samples, high PAH levels, healthy people exposed to this environment did not show significative damage in their genetic material. However, the evaluation of different environmental and genetic damage in such population is necessary to monitor possible damages.

Susceptibility to DNA damage in workers occupationally exposed to pesticides, to tannery chemicals and to coal dust during mining

Our mutagenesis group has been studying with important economic drivers of our state, such as agriculture, the foot-wear and leather industry and open-cast coal mining. Working conditions in these sectors have potentially harmful to humans. The aim of these studies is to determine the health risk of workers by biomonitoring subjects exposed to genotoxic agents. The main results of our studies with vineyard farmers we observed a high rate of MN and DNA damage in individuals exposed to pesticides (p < 0.001). In addition, some effects of genetic polymorphisms in the modulation of MN results were observed in this group. Tobacco farmers were also evaluated at different crop times. The results showed a significant increase in the Damage index and frequency in tobacco farmers compared to the non-exposed group, for all crop times. The results for footwear and tannery workers showed a significant increase in the mean ID for the solvent-based adhesive (p < 0.001) group in comparison to the water-based adhesive group and control (p < 0.05). For open-cast coal mine workers, the EBCyt indicated a significant increase in nuclear bud frequency and cytokinetic defects in the exposed group compared to the non-exposed group (p < 0.0001). We were able to associate specific genetic susceptibility with each type of exposure and with the non-use or improper use of personal protection equipment and diet adequacy. These results show how important the continuous education of exposed workers is to minimizing the effect of the occupational exposure and the risk of disease associated with the work.

Genotoxic biomonitoring of tobacco farmers: Biomarkers of exposure, of early biological effects and of susceptibility

Tobacco farming presents several hazards to those who cultivate and harvest the plant. The genotoxic and mutagenic effects in tobacco farmers were investigated. In order to verify the relationship between genetic susceptibility and biomarkers GSTT1, GSTM1, GSTP1, CYP2A6, PON, OGG1, RAD51, XRCC1, and XRCC4 genes polymorphism were evaluated. Oxidative stress markers and trace elements content were determined. Peripheral blood cells samples were collected from 111 agricultural workers during pesticides application and leaf harvest, and 56 non-exposed subjects. Results show that farmers are exposed to mixture of substances with genotoxic and cytotoxic potential. Only GSTM1 null and CYP2A6*9 showed significant associations with cytokinesis-blocked micronuclei assay results. In pesticide application an increase in trace elements content was observed. The results indicated that exposure to pesticides and nicotine can influence antioxidant enzymes activity. Our study drives the attention once more to the need for occupational training on safe work environment for farm workers.

Chemical exposure in occupational settings and related health risks: a neglected area of research in Pakistan

In Pakistan a huge number of workers is routinely exposed to various types of chemical contaminants but there is a dearth of information as to the impact of these agents, due to a lack of a routine surveillance system and proper reporting. Prolonged and sometimes acute occupational exposures to varied organic chemicals may result in numerous health related problems. Studies from all over the world have shown adverse health outcomes of chemicals that are commonly used in various occupations. Such chemical exposures are not just confined to the workplace, but the residents surrounding industrial sites also face significant health risks due to indirect chemical exposure. Occupational exposure is a multidimensional risk factor that varies from one occupation to another, and is associated with health decline in workers. Common determinants of workplace hazards include improper, or lack of use of self-protective equipment, active and passive exposure to cigarette smoke as well as the socio-demographic and economic background of workers. There may be more than one cause of occupational stress and psychophysical disturbance among workers such as workload, lower salaries, and lack of social and medical facilities; indeed, their general health is poor. Therefore, in Pakistan, it is particularly important to focus on these issues and set rules and regulations to create occupational hazard awareness among workers, which will promote health safety at work places. If priorities are given to the correct use of self-protective equipment, adopting proper hygiene at the workplace and to avoid smoking, occupational exposures and consequent health risks may be minimized significantly.

Does GSTP1 polymorphism contribute to genetic damage caused by ageing and occupational exposure?

The aim of our study was to see the effects of GSTP1 polymorphism on biomarkers of ageing, including micronuclei (MN), comet tail length, and relative telomere length in automobile repair workers, who are exposed to a broad spectrum of potential mutagens. The analysis was performed on buccal cells collected from occupationally exposed and non-exposed (control) subjects. Samples were analysed using cytogenetic and molecular methods, including restriction fragment length polymorphism (RFLP), MN test, comet assay, and real-time PCR. The results confirmed the DNA damaging effects of substances used in the mechanical workshops, but did not confirm the influence of GSTP1 gene polymorphism on DNA damage. However, further studies on both occupationally exposed and control populations are needed to understand the relationship between GSTP1 polymorphism and genome damage.

Micronucleus frequency in children exposed to biomass burning in the Brazilian Legal Amazon region: a control case study

BACKGROUND

The Amazon represents an area of 61% of Brazilian territory and is undergoing major changes resulting from disorderly economic development, especially the advance of agribusiness. Composition of the atmosphere is controlled by several natural and anthropogenic processes, and emission from biomass burning is one with the major impact on human health. The aim of this study was to evaluate genotoxic potential of air pollutants generated by biomass burning through micronucleus assay in exfoliated buccal cells of schoolchildren in the Brazilian Amazon region.

METHODS

The study was conducted during the dry seasons in two regions of the Brazilian Amazon. The assay was carried out on buccal epithelial cells of 574 schoolchildren between 6-16 years old.

RESULTS

The results show a significant difference between micronucleus frequencies in children exposed to biomass burning compared to those in a control area.

CONCLUSIONS

The present study demonstrated that in situ biomonitoring using a sensitive and low cost assay (buccal micronucleus assay) may be an important tool for monitoring air quality in remote regions. It is difficult to attribute the increase in micronuclei frequency observed in our study to any specific toxic element integrated in the particulate matters. However, the contribution of the present study lies in the evidence that increased exposure to fine particulate matter generates an increased micronuclei frequency in oral epithelial cells of schoolchildren.

Evaluation of genotoxicity and oxidative damage in painters exposed to low levels of toluene

Toluene is an organic solvent used in numerous processes and products, including industrial paints. Toluene neurotoxicity and reproductive toxicity are well recognized; however, its genotoxicity is still under discussion, and toluene is not classified as a carcinogenic solvent. Using the comet assay and the micronucleus test for detection of possible genotoxic effects of toluene, we monitored industrial painters from Rio Grande do Sul, Brazil. The putative involvement of oxidative stress in genetic damage and the influences of age, smoking, alcohol consumption, and exposure time were also assessed. Although all biomarkers of toluene exposure were below the biological exposure limits, painters presented significantly higher DNA damage (comet assay) than the control group; however, in the micronucleus assay, no significant difference was observed. Painters also showed alterations in hepatic enzymes and albumin levels, as well as oxidative damage, suggesting the involvement of oxidative stress. According to multiple linear regression analysis, blood toluene levels may account for the increased DNA damage in painters. In summary, this study showed that low levels of toluene exposure can cause genetic damage, and this is related to oxidative stress, age, and time of exposure.

Occupational genotoxicity among copper smelters

Occupational exposure in a copper smelting industry may produce various adverse health effects including cancer. Despite a number of well-documented studies reporting an increased risk of cancer among copper smelter workers, the data on genotoxic effects in this industry are scarce. In view of the above, an assessment of DNA damage in peripheral blood leukocytes by Comet assay from copper smelter workers was undertaken. Additionally, the proton-induced X-ray emission (PIXE) analysis was assessed to determine the metal content of samples. The study was conducted with all workers from a copper smelter (males; n = 11), and a control group ( n = 11) was recruited. The results of our study showed a significant increase ( p < 0.001; Mann-Whitney test) in DNA damage in peripheral blood lymphocytes of smelter workers, compared to the controls ( p < 0.001; Mann-Whitney test). No correlation between DNA damage or metal concentration and age mean or time of exposure was found under study. Our findings indicate that copper smelter workers have increased levels of DNA damage in somatic cells, suggesting a potential health risk for the workers. PIXE results show the presence of copper, iron, and other metals.

Abnormal blood levels of trace elements and metals, DNA damage, and breast cancer in the state of Kuwait

This study aims at investigating the blood level of Cu, Zn, Se, and Cd in breast cancer patients and the association between such level and the frequency of micronucleated lymphocytes. Fifty stage I breast cancer patients were recruited for this study at the time of diagnosis and before receiving any treatment or surgery. The control group consisted of 150 normal females matched to the patients for age (± 5 years). The whole blood level of Cu, Zn, Se, and Cd was determined using spectrophotometry. The frequency of micronucleated lymphocytes in the blood was determined using the cytokinesis-block micronucleus assay. The level of Cu, Zn, and Se was significantly lower (p = 0.0006, <0.0001, and <0.0001, respectively) in breast cancer patients, as compared to controls. The level of Cd was significantly (p < 0.0001) higher in the patients, as compared to controls. The frequency of lymphocytes with one micronucleus was significantly (p < 0.0001) higher in the patients, as compared to controls. In breast cancer patients, the frequency of micronucleated lymphocytes showed different associations with different levels of these trace elements. High Cd, low Zn, low Se, and both high and low Cu levels were significantly associated with micronucleus formation in lymphocytes. A similar association was found in the normal control group only in relation to high Se and Cd levels. Breast cancer patients seem to have abnormal levels of Cu, Zn, Se, and Cd, and such abnormality is associated with micronucleus formation in lymphocytes.

Paraoxonase-1 genetic polymorphisms and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides

Human paraoxonase 1 (PON1) is a lipoprotein-associated enzyme involved in the detoxification of organophosphate pesticides (OPs) by hydrolyzing the bioactive oxons. Polymorphisms of the PON1 gene are responsible for variation in the expression and catalytic activity of PON1 enzyme. In the present study, we have determined (a) the prevalence of two common PON1 polymorphisms, (b) the activity of PON1 and acetylcholinesterase enzymes, and (c) the influence of PON1 genotypes and phenotypes variation on DNA damage in workers exposed to OPs. We examined 230 subjects including 115 workers exposed to OPs and an equal number of normal healthy controls. The results revealed that PON1 activity toward paraoxon (179.19±39.36 vs. 241.52±42.32nmol/min/ml in controls) and phenylacetate (112.74±17.37 vs. 134.28±25.49μmol/min/ml in controls) was significantly lower in workers than in control subjects (p<0.001). No significant difference was observed in the distribution of genotypes and allelic frequencies of PON1(192)QR (Gln/Arg) and PON1(55)LM (Leu/Met) in workers and control subjects (p>0.05). The PON1 activity toward paraoxonase was found to be significantly higher in the R/R (Arg/Arg) genotypes than Q/R (Gln/Arg) and lowest in Q/Q (Gln/Gln) genotypes in both workers and control subjects (p<0.001). For PON1(55)LM (Leu/Met), PON1 activity toward paraoxonase was observed to be higher in individuals with L/L (Leu/Leu) genotypes and lowest in individuals with M/M (Met/Met) genotypes in both groups (p<0.001). No influence of PON1 genotypes and phenotypes was seen on the activity of acetylcholinesterase and arylesterase. The DNA damage was observed to be significantly higher in workers than in control subjects (p<0.05). Further, the individuals who showed least paraoxonase activity i.e., those with (Q/Q [Gln/Gln] and M/M [Met/Met]) genotypes showed significantly higher DNA damage compared to other isoforms in workers exposed to OPs (p<0.05). The results indicate that the individuals with PON1 Q/Q and M/M genotypes are more susceptible toward genotoxicity. In conclusion, the study suggests wide variation in enzyme activities and DNA damage due to polymorphisms in PON1 gene, which might have an important role in the identification of individual risk factors in workers occupationally exposed to OPs.

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.

BER gene polymorphisms (OGG1 Ser326Cys and XRCC1 Arg194Trp) and modulation of DNA damage due to pesticides exposure

The susceptibility of individuals to the genotoxic effect of pesticides can be modulated by genetic variations in the xenobiotic detoxification and DNA repair processes. This study evaluates if the two BER polymorphisms (XRCC1Arg194Trp and OGG1Ser326Cys) or the combined genotypes of these polymorphisms with PON1Gln192Arg could modify individual susceptibility to pesticide exposure in vineyard workers, as measured by micronucleus formation and DNA damage induction in peripheral leukocytes. The study population comprised 108 agricultural workers exposed to pesticides and 65 nonexposed. Our results demonstrate that individuals with the variant allele (OGG1Cys) showed higher DNA damage, detected by the comet assay, in relation to individuals carrying the wild-type OGG1Ser allele. Considering the combined influence of metabolizing PON1 and the DNA repair OGG1 genes, we observed significantly higher DNA damage in the comet assay in the exposed group when a less efficient OGG1Cys allele was acting independently of the PON1 genotype, reinforcing the importance of the OGG1 repair enzyme in the response to DNA damage by pesticide exposure. The association of the PONGln/Gln genotype with higher MN frequency suggests that the PON1 genotype is a major determinant of genotoxic risk in individuals exposed to pesticides. Analysis of the compared effect of XRCC1 and PON1 genotypes in the exposed group suggested that, among the poorly metabolizing PON1Gln/Gln individuals, the XRCC1Arg/Trp genotype has a protective effect with respect to MN formation. These results indicate that enhanced XRCC1 function may provide some protection from the enhanced genotoxic risk associated with inefficient xenobiotic detoxification in the studied population.

Thinner inhalation effects on oxidative stress and DNA repair in a rat model of abuse

Humans can come into contact with thinner by occupational exposure or by intentional inhalation abuse. Numerous studies of workers for genotoxic effects of thinner exposure have yielded conflicting results, perhaps because co-exposure to variable other compounds cannot be avoided in workplace exposure studies. In contrast, there is no data concerning the genotoxic effects of intentional inhalation abuse. The aim of this project was to examine the genotoxic effects of thinner inhalation in an animal model of thinner abuse (rats exposed to 3000 ppm toluene, a high solvent concentration over a very short, 15 min time period, twice a day for 6 weeks). The data presented here provides evidence that thinner inhalation in our experimental conditions is able to induce weight loss, lung abnormalities and oxidative stress. This oxidative stress induces oxidative DNA damage that is not a characteristic feature of genotoxic damage. No significant difference in DNA damage and DNA repair (biomarkers of genotoxicity) in lymphocytes from thinner-treated and control rats was found. Lead treatment was used as a positive control in these assays. Finally, bone marrow was evaluated as a biomarker of cellular alteration associated with thinner inhalation. The observed absence of hemopoietic and genetic toxicity could be explained in part by the absence of benzene, the only carcinogenic component of thinner; however, benzene is no longer a common component of thinner. In conclusion, thinner did not cause genotoxic effects in an experimental model of intentional abuse despite the fact that thinner inhalation induces oxidative stress.