Genotoxic assessment in tobacco farmers at different crop times

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.

Dry tobacco leaves: an in vivo and in silico approach to the consequences of occupational exposure

Exposure of tobacco workers handling dried tobacco leaves has been linked to an increased risk of toxicity and respiratory illness due to the presence of nicotine and other chemicals. This study aimed to evaluate the DNA damage caused by the exposure of tobacco growers during the dry leaf classification process and the relation to cellular mechanisms. A total of 86 individuals participated in the study, divided into a group exposed to dry tobacco (n = 44) and a control group (n = 42). Genotoxicity was evaluated using the alkaline comet assay and lymphocyte micronucleus (MN) assay (CBMN-Cyt), and measurement of telomere length. The levels of oxidative and nitrosative stress were evaluated through the formation of thiobarbituric acid reactive species, and nitric oxide levels, respectively. The inorganic elements were measured in the samples using particle-induced X-ray emission method. The combination of variables was demonstrated through principal component analysis and the interactions were expanded through systems biology. Comet assay, MN, death cells, thiobarbituric acid reactive species, and nitrosative stress showed a significant increase for all exposed groups in relation to the control. Telomere length showed a significant decrease for exposed women and total exposed group in relation to men and control groups, respectively. Bromine (Br) and rubidium (Rb) in the exposed group presented higher levels than control groups. Correlations between nitrate and apoptosis; Br and MN and necrosis; and Rb and telomeres; besides age and DNA damage and death cells were observed. The systems biology analysis demonstrated that tobacco elements can increase the nuclear translocation of NFKB dimers inducing HDAC2 expression, which, associated with BRCA1 protein, can potentially repress transcription of genes that promote DNA repair. Dry tobacco workers exposed to dry leaves and their different agents showed DNA damage by different mechanisms, including redox imbalance.

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.

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.

Farmers exposed to pesticides have almost five times more DNA damage: a meta-analysis study

We carried out a meta-analytical review of possible DNA damage resulting from occupational exposure to pesticides in farmers in the scientific literature. After the search, screening, and eligibility criteria steps, we included 42 studies to analyze random effect calculation. DNA damage in farmers occupationally exposed to pesticides represents an effect of SMD 4.63 [CI 95% 3.94-5.32; p <0.001]. We observed a high heterogeneity rate between the studies and an asymmetry of the bias analysis results. We performed a meta-regression on the parameters. The Olive Tail Moment (OTM) was the most effective comet assay parameter in the evaluated studies. The Damage Index (DI) was more conservative and highlighted the variability between studies caused by distinct methodologies that showed more significant effects and greater deviations. An analysis of confounding factors demonstrated a slight DNA damage in smokers who were occupationally exposed to pesticides compared to nonsmokers, indicating genotoxicity but smaller than the pesticide effect. The present study shows the greater risk that occupationally exposed rural workers have of developing related diseases due to pesticides' genotoxic effect.

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.

Assessment of Cytogenetic Damage and Cholinesterases' Activity in Workers Occupationally Exposed to Pesticides in Zamora-Jacona, Michoacan, Mexico

Pesticides have been considered as potential chemical mutagens; however, little is known about toxic and genotoxic effects during pesticide application in Zamora-Jacona, Michoacan State in Mexico. This study sought to determine DNA damage and cholinesterase activities inhibitions in 54 agricultural workers exposed to complex mixtures of pesticides vs. control group (26 individuals) using Comet assay in peripheral whole blood, micronucleus (MN) test in oral mucosa cells, Cytokinesis-blocked MN assay in lymphocytes (L-CBMNcyt) and measuring AChE and BChE activities in whole blood and plasma samples, respectively. Exposed subjects demonstrated significantly elevated levels of primary (Comet assay: tail intensity, tail length, tail moment, Olive tail moment) and permanent DNA damage (MN assay: in blood/buccal cells; frequencies of nuclear buds, binucleated cells, cells with condensed chromatin, karyorrhexis, pyknosis, and karyolysis). However, inhibition of cholinesterase activities (AChE and BChE) was not observed in the workers. Confounding factors including sex, age, BMI, working exposure period, protection level, smoking habit (cigarettes per day units), alcohol consumption (weekly), medication, were considered in the analysis. These combined techniques demonstrated usefulness in the health hazards risks pesticide exposure assessment and suggested the need for periodic monitoring together with the education and the training of occupational workers for the safe application of potentially harmful pesticides.

Occupational exposure to pesticides: Genetic danger to farmworkers and manufacturing workers - A meta-analytical review

In the last decades, the use of pesticides has grown worldwide. However, there is great worry about the impact of pesticides on human health, due to their wide distribution and possible long-term effects. Complex mixtures with different formulations are often used, including a variety of genotoxic compounds. Thus, genotoxicity tests form an important part of cancer research and risk assessment of potential carcinogens. This study aimed to conduct a meta-analytical review of possible genetic damage resulting from occupational exposure in farmworkers and workers employed in pesticide production, both ever in comparison to non-exposed people, using comet assay (CA), micronucleus test (MN) and telomere length (TL) data available in the scientific literature. A total of 145 datasets were evaluated. The results showed that the occupationally exposed workers had more DNA damage in CA and MN than non-exposed workers. The TL result did not show difference between groups. When the data were categorized by gender (male, female or both), crop (general, tobacco, fruits, soybeans, cotton) and occupation (manufacturing or farmworkers), the study found that the exposed group always presented higher damage than the non-exposed individuals, in CA and MN. More studies with TL are needed to obtain a more precise response, and to segregate the effect of tobacco farming from pesticide exposure. When TL was segregated by gender, women and men presented difference between exposed and non-exposed groups. In general, the publication bias impact was modest. If all relevant studies were included, the key finding (i.e. the effect of pesticide exposure increases the genotoxicity and mutation rate) would probably remain unchanged. Lastly, it is important to highlight the importance of the use of personal protective equipment (PPE), and offer safer options to farmworkers (e.g. organic farming or less toxic alternatives).

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.

Increased levels of genotoxic damage in a Bolivian agricultural population exposed to mixtures of pesticides

During the past decades, farmers in low to middle-income countries have increased their use of pesticides, and thereby the risk of being exposed to potentially genotoxic chemicals that can cause adverse health effects. Here, the aim was to investigate the correlation between exposure to pesticides and genotoxic damage in a Bolivian agricultural population. Genotoxic effects were assessed in peripheral blood samples by comet and micronucleus (MN) assays, and exposure levels by measurements of 10 urinary pesticide metabolites. Genetic susceptibility was assessed by determination of null frequency of GSTM1 and GSTT1 genotypes. The results showed higher MN frequency in women and farmers active ≥8 years compared to their counterpart (P < 0.05). In addition, age, GST genotype, alcohol consumption, and type of water source influenced levels of genotoxic damage. Individuals with high exposure to tebuconazole, 2,4-D, or cyfluthrin displayed increased levels of genotoxic damage (P < 0.05-0.001). Logistic regression was conducted to evaluate associations between pesticide exposure and risk of genotoxic damage. After adjustment for confounders, a significant increased risk of DNA strand breaks was found for high exposure to 2,4-D, odds ratio (OR) = 1.99 (P < 0.05). In contrast, high exposure to pyrethroids was associated with a reduced risk of DNA strand breaks, OR = 0.49 (P < 0.05). It was also found that high exposure to certain mixtures of pesticides (containing mainly 2,4-D or cyfluthrin) was significantly associated with increased level and risk of genotoxic damage (P < 0.05). In conclusion, our data show that high exposure levels to some pesticides is associated with an increased risk of genotoxic damage among Bolivian farmers, suggesting that their use should be better controlled or limited.

A longitudinal follow-up study of oxidative stress and DNA damage among farmers exposed to pesticide mixtures

Exposure to pesticides may have increased risk of oxidative stress and genetic damage and hence of development of chronic diseases. The aim of this longitudinal follow-up study is to compare oxidative stress and DNA damage between the pre- and post-pesticide application seasons among 56 male farmers. The study also investigated the factors associated with changes in oxidative stress, DNA damage, and health symptoms during the pesticide application season. The eligibility criteria for the subjects were men aged between 25 and 55 years, applied pesticide mixtures during May and June 2018, and healthy without current illness. Ten milliliters of venous blood samples was collected twice from each subject in the pre- and post-pesticide application seasons for determination of superoxide dismutase (SOD), 8-hydroxy-2'-deoxyguanosine (8-OHdG), comet tail length, and comet tail moment. The remarkable findings included a statistically significant increase in SOD activity during the pesticide application season (P < 0.001). However, there were no statistical differences in 8-OHdG, comet tail length, and comet tail moment. When we analyzed the factors associated with changes in SOD activity during the pesticide application season by using linear regression analysis, working hours on the farm (B ± SE. = 0.790 ± 0.341, P = 0.025) and planting activities (B ± SE. = 1.217 ± 0.504, P = 0.020) were associated with increase in SOD activity. Therefore, increase in SOD may be a consequence of oxidative damage induced by pesticide exposure and this marker may be used as an early warning for pesticide-induced acute and chronic toxicities.

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.

Role of PON1, SOD2, OGG1, XRCC1, and XRCC4 polymorphisms on modulation of DNA damage in workers occupationally exposed to pesticides

Tobacco farming has been proving to induce poor health outcomes in agricultural workers, genomic instability being the triggering one. This study evaluated influence of PON1 (paraoxonase 1), SOD2 (superoxide dismutase), OGG1 (8-oxoguanine glycosylase), XRCC1 (X-ray repair cross-complementing protein 1), and XRCC4 (X-ray repair cross-complementing protein 4) genes polymorphisms on DNA damage in 121 subjects occupationally exposed to pesticides mixtures and nicotine at tobacco fields and 121 non-exposed individuals. Inorganic elements (Cl, P, S and Zn) and cotinine levels were found increased in farmers, confirming exposure. Results show higher frequencies of buccal micronucleus (MN), nuclear buds (NBUD), binucleated cells (BN) and damage index (comet assay), reduced telomere length (TL), and increased parameters of oxidative stress in farmers compared to non-exposed individuals. PON1 Gln/Gln genotype was associated with increased MN frequency. SOD2 Val/Val showed association with increased frequency of MN and NBUD and decreased antioxidant activity. The XRCC1 Arg/Arg showed protective effect for MN, BN and TL, which was also positively influenced by OGG1 -/Cys. MN was decreased in XRCC4 -/Ile farmers. These genotypes also showed a risk for antioxidant activity. Our study proposes that PON1 and SOD2 variants play a role in xenobiotic-metabolizing system in farmers, while base excision repair (BER) pathway could be the repair mechanism involved in genomic instability suffered by tobacco farmers.

Occupational Exposure to Pesticides in Tobacco Fields: The Integrated Evaluation of Nutritional Intake and Susceptibility on Genomic and Epigenetic Instability

Pesticides used at tobacco fields are associated with genomic instability, which is proposed to be sensitive to nutritional intake and may also induce epigenetic changes. We evaluated the effect of dietary intake and genetic susceptibility polymorphisms in MTHFR (rs1801133) and TERT (rs2736100) genes on genomic and epigenetic instability in tobacco farmers. Farmers, when compared to a nonexposed group, showed increased levels of different parameters of DNA damage (micronuclei, nucleoplasmic bridges, and nuclear buds), evaluated by cytokinesis-block micronucleus cytome assay. Telomere length (TL) measured by quantitative PCR was shorter in exposed individuals. Global DNA methylation was significantly decreased in tobacco farmers. The exposed group had lower dietary intake of fiber, but an increase in cholesterol; vitamins such as B6, B12, and C; β-carotene; and α-retinol. Several trace and ultratrace elements were found higher in farmers than in nonfarmers. The MTHFR CT/TT genotype influenced nucleoplasmic bridges, nuclear buds, and TL in the exposed group, whereas TERT GT/TT only affected micronucleus frequency. We observed a positive correlation of TL and lipids and an inverse correlation of TL and fibers. The present data suggest an important role of dietary intake and subjects' genetic susceptibility to xenobiotics-induced damages and epigenetic alterations in tobacco farmers occupationally exposed to mixtures of pesticides.

Chronic occupational exposure endured by tobacco farmers from Brazil and association with DNA damage

Tobacco farming is an important economic income in Brazil, although it has been challenged as regard the occupational exposure to both pesticides and nicotine endured by farmers. Chronic occupational exposure to complex mixtures can lead to health hazardous. We examined genomic instability and epigenetic changes in tobacco farmers occupationally exposed to pesticide mixtures and nicotine at tobacco fields. DNA damage was assessed by alkaline comet assay in blood cells. Genomic DNA was isolated, and telomere length was measured using quantitative polymerase chain reaction assay. We measured 5-methyl-2'-deoxycytidine, a marker of global DNA methylation, and p16 promoter methylation. The oxidative profile was evaluated by trolox equivalent antioxidant capacity and lipid peroxidation (thiobarbituric acid reactive substances) in serum. Exposure parameters, plasma cotinine and inorganic element levels, were also measured. DNA damage was significantly elevated for farmers in relation to unexposed group (P < 0.001; Mann-Whitney test) and positively associated with years of exposure. Inverse relationship between DNA damage and total equivalent antioxidant activity was demonstrated for exposed and unexposed groups. Exposed group showed significantly shorter telomeres (P < 0.001; unpaired t-test) and DNA hypomethylation (P < 0.001; unpaired t-test), as well as p16 hypermethylation (P = 0.003; Mann-Whitney test). Lipid peroxidation was increased for exposed group in relation to unexposed one (P = 0.02; Mann-Whitney test) and presented a positive correlation with global DNA methylation (P = 0.0264). Farmers have increased plasma cotinine levels (P < 0.001) and inorganic elements (phosphorus, sulphur and chlorine) in relation to unexposed group. Elevated oxidative stress levels due to chronic occupational pesticide mixtures and nicotine exposure in tobacco farmers were associated with higher DNA damage, shorter telomeres and altered DNA methylation. Telomere-accelerated attrition due to exposure may be potential intermediate step before a disease state.

Simultaneous determination of residues of metalaxyl, cyazofamid and a cyazofamid metabolite in tobacco leaves and soil by liquid chromatography with tandem mass spectrometry

A simple method was developed and validated for the simultaneous determination of metalaxyl, cyazofamid and the cyazofamid metabolite 4-chloro-5-p-tolylimidazole-2-carbonitrile (CCIM) by liquid chromatography with tandem mass spectrometry. The three target compounds were extracted from tobacco and soil with acetonitrile containing 0.1% acetic acid, and the extracts were purified using octadecylsilane. The proposed method showed satisfactory linearity (R2 ≥ 0.9985) for the target compounds. The limits of detection for metalaxyl, cyazofamid and CCIM were 0.006, 0.06 and 0.06 mg/kg in soil and green tobacco leaves and 0.03, 0.3 and 0.3 mg/kg in cured tobacco leaves, respectively. The limits of quantification for metalaxyl, cyazofamid and CCIM were 0.02, 0.2 and 0.2 mg/kg in soil and green tobacco leaves and 0.1, 1 and 1 mg/kg in cured tobacco leaves, respectively. The average recoveries from soil and tobacco were 72.91-98.40% for metalaxyl, 76.73-105.80% for cyazofamid and 74.48-106.45% for CCIM. The relative standard deviation range was 1.23-6.99%. The developed method was successfully applied to analysis of residues of metalaxyl, cyazofamid and CCIM in real soil and tobacco samples. The results indicated that the established method could meet the requirement for the analysis of trace amounts of all three analytes in soil and tobacco.

Assessment of DNA damages in lymphocytes of agricultural workers exposed to pesticides by comet assay in a cross-sectional study

PURPOSE

To assess the predictive power of the comet assay in the context of occupational exposure to pesticides.

MATERIALS AND METHODS

The recruited subjects completed a structured questionnaire and gave a blood sample. Exposure to pesticides was measured by means of an algorithm based on Dosemeci's work (Agricultural Health Study). Approximately 50 images were analyzed for each sample via fluorescence microscopy. The extent of DNA damage was estimated by tail moment (TM) and is the product of tail DNA (%) and tail Length.

RESULTS

Crude significant risks (odds ratios, ORs) for values higher than the 75th percentile of TM were observed among the exposed subjects (score > 1). The frequency of some confounding factors (sex, age and smoking) was significantly higher among the exposed workers. A significant dose-effect relationship was observed between TM and exposure score. Significant high-risk estimates (ORs), adjusted by the studied confounding factors, among exposure to pesticides and TM, % tail DNA and tail length were confirmed using unconditional logistic regression models.

CONCLUSIONS

The adjusted associations (ORs) between the comet parameters and exposure to pesticides were significant. The sensitivity of the comet test was low (41%), the specificity (89%) and the predictive positive value (0.77) were found acceptable.

DNA damage and epigenetic alteration in soybean farmers exposed to complex mixture of pesticides

Exposure to pesticides can trigger genotoxic and mutagenic processes through different pathways. However, epidemiological studies are scarce, and further work is needed to find biomarkers sensitive to the health of exposed populations. Considering that there are few evaluations of soybean farmers, the aim of this study was to assess the effects of human exposure to complex mixtures of pesticides. The alkaline comet assay modified with restriction enzyme (hOGG1: human 8-oxoguanine DNA glycosylase) was used to detect oxidised guanine, and compared with the buccal micronucleus cytome assay, global methylation, haematological parameters, biochemical analyses (serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, gamma-glutamyl-transferase and butyrylcholinesterase), and particle-induced X-ray emission (PIXE) for the analysis of inorganic elements. Farm workers (n = 137) exposed to different types of pesticides were compared with a non-exposed reference group (control; n = 83). Results of the enzyme-modified comet assay suggest oxidation of guanine in DNA generated by pesticides exposure. It was observed that DNA damage (comet assay and micronucleus test) was significantly increased in exposed individuals compared to the unexposed group. The micronucleus test demonstrated elimination of nuclear material by budding, defective cytokinesis and dead cells. Occupationally exposed individuals also showed genomic hypermethylation of DNA, which correlated with micronucleus frequency. No differences were detected regarding the haematological and biochemical parameters. Finally, significantly higher concentrations of Al and P were observed in the urine of the soybean farmers. DNA damage could be a consequence of the ability of the complex mixture, including Al and P, to cause oxidative damage. These data indicate that persistent genetic instability associated with hypermethylation of DNA in soybean workers after long-term exposure to a low-level to pesticides mixtures may be critical for the development of adverse health effects such as cancer.

Preparation of an Environmentally Friendly Formulation of the Insecticide Nicotine Hydrochloride through Encapsulation in Chitosan/Tripolyphosphate Nanoparticles

Insecticide nicotine hydrochloride (NCT) was formulated as nanoparticles composed of chitosan (CS) and sodium tripolyphosphate (TPP) to undermine its adverse impacts on human health and reinforce its physicochemical stability. The study investigated the preparation and characterization of chitosan/tripolyphosphate nanoparticles (CS/TPP NPs) with good encapsulation efficiency (55%), uniform morphology, and physicochemical stability (45 days) through dynamic light scattering (DLS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS) measurements. A bioassay against Musca domestica NCT CS/TPP NPs exhibited good bioactivity and thermal stability. The effect of the monovalent salt (NaCl) on manipulating the formation and size distribution of ionically cross-linked nanoparticles was demonstrated as well. The formulation of NCT CS/TPP NPs could be a utility candidate in public health and agriculture.

Markers of genotoxicity and oxidative stress in farmers exposed to pesticides

The effects of chronic exposure to pesticides can lead to the development of several diseases, including different types of cancer, since the genotoxic and mutagenic capacity of these substances can be observed. The objective of this study is to investigate the relation between the occupational exposure to various pesticides and the presence of DNA damage and oxidative stress. Blood samples from 50 rural workers (41 men and 9 women) exposed to pesticides, 46 controls (20 men and 26 women) from the same city (Antônio Carlos, Santa Catarina state, Brazil) and 29 controls (15 men and 14 women) from another city (Florianópolis, Santa Catarina state, Brazil), were evaluated using the comet assay and the cytokinesis-block micronucleus (CBMN) technique for genetic damage, and the test of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity for the oxidative stress. Cholinesterase activities were also determined, but there was no statistical difference among exposed workers and controls. Significant differences were found in DNA damage among groups. The comet assay performed on peripheral blood lymphocytes of these individuals had a significantly higher DNA damage index in the exposed group comparing to controls (p < 0.0001). MNi (p < 0.001), NBUDs (p < 0.005) and NPBs (p < 0.0001) were also found to be significantly higher in the exposed group. The TBARS values were significantly higher comparing to the Florianopolis control group (p < 0.0001). Even though CAT values were higher than controls, there was no statistical difference. Thus, it is concluded that the exposed individuals, participants of this study, are more subject to suffer genetic damage and, consequently, more susceptible to diseases resulting from such damages.

Influence of vitamin intake and MTHFR polymorphism on the levels of DNA damage in tobacco farmers

BACKGROUND

Genetic damage may occur spontaneously under normal metabolic circumstances, inadequate intake of nutrients, and excessive exposure to environmental mutagens.

OBJECTIVES

To evaluate the influence of the intake of micronutrients vitamin B12, vitamin B6, and folate and of the polymorphism methylenetetrahydrofolate reductase (MTHFR) C677T on the induction of DNA damage in tobacco farmers.

METHODS

The study involved 66 men and 44 women engaged in tobacco cultivation in the region of Venâncio Aires (Rio Grande do Sul state, Brazil). Peripheral blood samples were collected to analyze DNA damage using the Comet assay, the micronucleus (MN) test and MTHFR C677T polymorphism. Dietary intake was evaluated based on the mean values obtained from three 24-h diet recall questionnaires, and nutrient intake data were computerized and estimated in the Food Processor SQL 10.9 program. The statistical tests used to generate the stated results were Kruskal-Wallis test, Exact Fisher's test, and multivariate linear regression analysis.

RESULTS

DNA damage was significantly higher in individuals who had an inadequate intake of folate, vitamin B12, and vitamin B6 (P < 0.01) assessed by Comet assay. In relation to MN test results, buccal cells showed MN frequency higher in individuals with inadequate intake of vitamin B6 (P < 0.01). No difference was observed in MN lymphocytes frequency. No significant association was detected between MTHFR C677T polymorphism and DNA damage in tobacco farmers.

CONCLUSION

Our results suggest that folate, vitamin B12, and vitamin B6 deficiency may be associated with genotoxic effect in individuals exposed to pesticides.

Environmental exposure and effects on health of children from a tobacco-producing region

Children may be environmentally exposed to several hazards. In order to evaluate the health of children living in a tobacco-producing region, different biomarkers of exposure and effect, as well as hematological parameters, were evaluated. Biomarkers of exposure to the following xenobiotics were assessed: pesticides, nicotine, toxic elements, and organic solvents. Oxidative damage markers malondialdehyde (MDA) and protein carbonyls (PCO), vitamin C, microalbuminuria (mALB) levels, and N-acetyl-β-D-glucosaminidase (NAG) activity were also evaluated. Peripheral blood samples and urine were collected from 40 children (6-12 years), at two different crop periods: in the beginning of pesticide applications (period 1) and in the leaf harvest (period 2). The Wilcoxon signed-rank test for paired data was used to evaluate the differences between both periods. Biomarkers of exposure cotinine in urine and blood chromium (Cr) levels were increased in period 1 when compared to period 2. Moreover, a significant reduced plasmatic activity of butyrylcholinesterase (BuChE) was observed in period 2 in relation to period 1. Blood Cr levels were above the recommended by WHO in both evaluations. The biomarkers MDA and PCO as well as the kidney dysfunction biomarker, mALB, presented levels significantly increased in period 1. Additionally, decreased lymphocytes and increased basophils were also observed. Cotinine was positively associated with PCO, and Cr was positively associated with PCO and MDA. The increased Cr levels were associated with decreased lymphocytes and increased basophils. Our findings demonstrate that children environmentally exposed to xenobiotics in rural area may present early kidney dysfunction, hematological alterations, as well as lipid and protein damages, associated with co-exposure to different xenobiotics involved in tobacco cultivation.

Evaluating genotoxic risks in Brazilian public health agents occupationally exposed to pesticides: a multi-biomarker approach

This is the first study demonstrating genotoxic effects and whole transcriptome analysis on community health agents (CHAs) occupationally exposed to pesticides in Central Brazil. For the transcriptome analysis, we found some genes related to Alzheimer's disease (LRP1), an insulin-like growth factor receptor (IGF2R), immunity genes (IGL family and IGJ), two genes related to inflammatory reaction (CXCL5 and CCL3), one gene related to maintenance of cellular morphology (NHS), one gene considered to be a strong apoptosis inductor (LGALS14), and several transcripts of the neuroblastoma breakpoint family (NBPF). Related to comet assay, we demonstrated a significant increase in DNA damage, measured by the olive tail moment (OTM), in the exposed group compared to the control group. Moreover, we also observed a statistically significant difference in OTM values depending on GSTM1 genotypes. Therefore, Brazilian epidemiological surveillance, an organization responsible for the assessment and management of health risks associated to pesticide exposure to CHA, needs to be more proactive and considers the implications of pesticide exposure for CHA procedures and processes.

Influence of exposure to pesticides on telomere length in tobacco farmers: A biology system approach

Various pesticides in the form of mixtures must be used to keep tobacco crops pest-free. Recent studies have shown a link between occupational exposure to pesticides in tobacco crops and increased damage to the DNA, mononuclei, nuclear buds and binucleated cells in buccal cells as well as micronuclei in lymphocytes. Furthermore, pesticides used specifically for tobacco crops shorten telomere length (TL) significantly. However, the molecular mechanism of pesticide action on telomere length is not fully understood. Our study evaluated the interaction between a complex mixture of chemical compounds (tobacco cultivation pesticides plus nicotine) and proteins associated with maintaining TL, as well as the biological processes involved in this exposure by System Biology tools to provide insight regarding the influence of pesticide exposure on TL maintenance in tobacco farmers. Our analysis showed that one cluster was associated with TL proteins that act in bioprocesses such as (i) telomere maintenance via telomere lengthening; (ii) senescence; (iii) age-dependent telomere shortening; (iv) DNA repair (v) cellular response to stress and (vi) regulation of proteasome ubiquitin-dependent protein catabolic process. We also describe how pesticides and nicotine regulate telomere length. In addition, pesticides inhibit the ubiquitin proteasome system (UPS) and consequently increase proteins of the shelterin complex, avoiding the access of telomerase in telomere and, nicotine activates UPS mechanisms and promotes the degradation of human telomerase reverse transcriptase (hTERT), decreasing telomerase activity.

Urinary Cotinine Levels Among Latino Tobacco Farmworkers in North Carolina Compared to Latinos Not Employed in Agriculture

INTRODUCTION

This analysis describes urinary cotinine levels of North Carolina Latino farmworkers, compares cotinine levels of farmworkers to those of Latinos non-farmworkers, determines factors associated with farmworker cotinine levels, and determines if differences in farmworker and non-farmworker cotinine levels are associated with smoking.

METHODS

Data are from 63 farmworkers and 44 non-farmworkers who participated in a larger study of occupational exposures. Questionnaire data and urine samples collected in 2012 and 2013 are analyzed.

RESULTS

Farmworkers had urinary cotinine levels that were far greater than the non-farmworker group. Geometric mean (GM) urinary cotinine levels for farmworkers were 1808.22ng/ml in 2012, and 396.03ng/ml in 2013; corresponding GM levels for non-farmworkers were 4.68ng/ml and 9.03ng/ml. Farmworker GM cotinine levels were associated with harvesting tobacco (1242.77ng/ml vs. 471.26ng/ml; P = .0048), and working in wet shoes (1356.41ng/ml vs. 596.93ng/ml; P = .0148). Smoking did not account for cotinine level differences; the GM cotinine level for farmworkers who did not smoke was 541.31ng/ml; it was 199.40ng/ml for non-farmworkers who did smoke.

CONCLUSION

North Carolina farmworkers experience large nicotine doses. The long-term health effects of these doses are not known. Although procedures to reduce occupational nicotine exposure are known, no changes in work practices or in policies to protect workers have been implemented. Research on the health effects of occupational nicotine exposure must become a priority. Current knowledge of occupational transdermal nicotine exposure must be used to improve occupational safety practice and policy for tobacco workers.

IMPLICATIONS

This study documents the heavy burden of nicotine exposure and dose experienced by tobacco workers in North Carolina. Hundreds of thousands of farmworkers and farmers in the United States and Canada, as well as agricultural workers around the world, share this burden of nicotine exposure and dose. These results support the need to change work practices and regulations to protect workers. They also document the need to delineate the health effects of long-term exposure to high transdermal nicotine doses.

The use of the lymphocyte cytokinesis-block micronucleus assay for monitoring pesticide-exposed populations

Pesticides are widely used around the world, and hundreds of millions of people are exposed annually in occupational and environmental settings. Numerous studies have demonstrated relationships between pesticide exposure and increased risk of cancers, neurodegenerative and neurodevelopmental disorders, respiratory diseases and diabetes. Assessment of genotoxicity of pesticides and biomonitoring their effect in exposed populations is critical for a better regulation and protection, but it can be complicated because pesticides are often used as complex mixtures. The cytokinesis-block micronucleus assay in human lymphocytes (L-CBMN) is a validated method of assessment of DNA damage induced by clastogenic and aneuploidogenic mechanisms. The goal of this review is to provide an updated summary of publications on biomonitoring studies using this assay in people exposed to pesticides in different settings, and to identify gaps in knowledge, and future directions. A literature search was conducted through MedLine/PubMed and TOXLINE electronic databases up to December 2015. A total of 55 full-text articles, related to 49 studies, excluding reviews, were selected for in depth analysis, divided by the settings where exposures occurred, such as chemical plant workers, pesticide sprayers, floriculturists, agricultural workers and non-occupationally exposed groups. Majority of studies (36 out of 49) reported positive findings with L-CBMN assay. However, most of the studies of professional applicators that used single pesticide or few compounds in the framework of specific programs did not show significant increases in MN frequency. A decreased level of pesticide-induced genotoxicity was associated with the proper use of personal protection. In contrast, subjects working in greenhouses or during intensive spraying season and having acute exposure, showed consistent increases in MN frequency. Overall, this analysis confirmed that L-CBMN is an excellent tool for pesticide biomonitoring, and can validate the effects of educational and intervention programs on reducing exposure and genetic damage.

Telomere measurement in individuals occupationally exposed to pesticide mixtures in tobacco fields

Occupational exposure to pesticides in tobacco fields causes genetic damage in farmers. The aim of this study was to analyze tobacco farmers chronically exposed to low doses of pesticides and nicotine (present in the tobacco leaves) in relation to absolute telomere length (aTL), and explore the influence of lifestyle characteristics, oxidative stress, and inorganic element levels. DNA was isolated from peripheral blood samples from agricultural workers and non-exposed individuals, and aTL was measured by quantitative real time polymerase chain reaction (qPCR) analysis. Oxidative stress (thiobarbituric acid reactive substances [TBARS], which measures oxidative damage to lipids; and toxic equivalent antioxidant capacity [TEAC], which measures total equivalent antioxidant capacity) was evaluated in serum, and inorganic element content was analyzed in whole blood through particle-induced X-ray emission technique. It was found that exposure to pesticides and tobacco smoking had significant effects on aTL. Individuals occupationally exposed to complex mixtures of pesticides in tobacco fields and individuals who smoked had decreased aTL compared with the non-exposed group. TBARS and TEAC were significantly elevated in the exposed group. There were no significant differences in inorganic elements. There was no evidence of an influence of age, gender, consumption of alcoholic beverages, or intake of fruits and vegetables on aTL within the groups. In addition, years of work in the tobacco field in the exposed group did not influence any of the variables analyzed. Although further studies were needed, these results suggested differences in telomere maintenance in tobacco farmers compared with the control group, indicating that telomere length may be a good biomarker of occupational exposure.