Genotoxic evaluation of workers employed in pesticide production

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.

Micronucleus frequencies in lymphocytes and reticulocytes in a pesticide-exposed population in Portugal

A wide range of chemical products known to be acutely toxic is currently used in the agricultural sector, including numerous pesticides with different compositions. Nevertheless, the effects in human health as result of chronic exposure to low levels are not yet completely understood. The methodology for determination of micronuclei (MN) in lymphocytes (CBMN) is well established, and accumulating data demonstrated a correlation to enhanced risk of cancer development. However, analysis of MN in reticulocytes (MN-RET) in humans is a recent tool on human biomonitoring. The aim of this study was to examine the influence of pesticide exposure on MN-RET and CBMN frequencies. In total, 177 individuals were studied (93 controls and 84 exposed). All individuals included in the exposed group were exposed regularly to various chemicals. Both MN-RET and CBMN were significantly higher in the exposed subjects compared to controls. The CBMN frequencies were quantitatively higher in females than males, especially within the exposed group. Smoking habits exerted no marked influence on the frequency of the biomarkers studied. A significant and positive correlation was found between both indicators. Within the exposed group, data showed that there was a significant correlation between MN-RET and recent exposure (exposure in the previous 10 d) that is not found when considering CBMN. It is conceivable that due to the short life span of reticulocytes, MN-RET were found to be more reliable to characterize recent genetic damage as opposed to CBMN.

Evaluation of a suitable DNA damage biomarker for human biomonitoring of exposed workers

The objective of this study was to identify a sensitive and noninvasive biomarker of early genotoxic effects, for health risk assessment of workers exposed to mixtures of low doses of xenobiotics. We studied 30 workers exposed to antineoplastic drugs, 57 workers exposed to different mixtures of polycyclic aromatic hydrocarbons (PAHs) (41 airport workers and 16 paving workers) and 76 controls. Comet and micronucleus (MN) tests were performed on lymphocytes and exfoliated buccal cells. The MN assay on lymphocytes did not show significant differences between exposed and controls, while the MN assay on exfoliated buccal cells showed higher values in workers exposed to antineoplastics as compared with controls (0.85 vs. 0.48, P = 0.042). The comet assay on lymphocytes showed a higher comet percentage value (18.11 vs. 11.24 in controls, P = 0.001) and mean tail moment (TM) value (21.84 vs. 16.72 in controls, P = 0.003) in individuals exposed to PAHs as compared with controls; no significant differences were found in exposed to antineoplastics. The comet assay on exfoliated buccal cells did not show significant differences between exposed and control groups for comet percentages, whereas the TM value was higher in workers exposed to PAHs (55.1 vs. 32.31 for controls, P < 0.001). These results show that exfoliated buccal cells, obtained by a noninvasive procedure, represent robust target cells to assess the occupational exposure to inhalable mixture of chemicals at low doses. The comet assay seems to be suitable to promptly evaluate the genotoxic effects of PAHs mixtures that also contain volatile substances. The MN test is suitable to evaluate the effects of antineoplastics. Inc.

Cytogenetic biomonitoring of Brazilian workers exposed to pesticides: micronucleus analysis in buccal epithelial cells of soybean growers

Pesticides have been considered potential chemical mutagens and various agrochemical ingredients possess mutagenic properties. Biomonitoring provides a useful tool to estimate the genetic risk from exposure to a complex mixture of chemicals. In general genetic damage associated with pesticides occurs in human populations subject to high exposure levels due to intensive use, misuse or failure of control measures. Few studies have been carried out using the micronucleus (MN) analysis in buccal cells of farm workers and, from the available data, only one has found a positive relationship. Micronuclei were analyzed in 29 Brazilian workers exposed to pesticides in soybean fields and in 37 non-exposed individuals. The results obtained indicate that the mean number of cells with MN in the exposed group (3.55+/-2.13) was significantly higher than in the control group (1.78+/-1.23). The number of cells with MN was not influenced by age, smoking habit, smoking time, number of cigarettes/day, alcohol consumption and years of exposure to pesticides. The genotoxic potential of the pesticides used in soybean fields may explain the detectable increase of cells with MN in exposed workers.

DNA damage in workers occupationally exposed to pesticide mixtures

Pesticides are used in agriculture to protect crops but represent at the same time a potential risk to farmers and environment. The aim of this work is the evaluation of 54 subjects occupationally exposed to pesticides and 30 subjects as a control group using the quantification of DNA damage level by means of the alkaline Comet assay and the evaluation of repair processes. Damage index Comet assay (DICA) and damage index repair assay (DIRA) were studied in 27 pesticide applicator workers, 27 non-pesticide applicators and controls. Our results show that both exposed groups revealed significant increase in DICA when compared with controls (P < 0.0001), as well as in DIRA (P < 0.0001). However, the spraying group exhibited a marginally significant difference in DICA (P = 0.05) when years of exposure are considered and a significant difference (P < 0.05) when the personal protective equipment used by individuals was taken as a comparison factor. The influence of confounding factors on the genotoxic effects of occupational exposure to pesticides was investigated and no significant differences were observed considering age, gender, smoking and alcohol consumption in relation to DICA and DIRA. Since DNA damage is an important step in events leading from carcinogen exposure to cancer disease, our study highlights the potential health risk associated with agrochemical exposure in developing countries with vast cultivated areas, such as Argentina.

Comparative evaluation of acetylcholinesterase status and genome damage in blood cells of industrial workers exposed to carbofuran

Literature data on carbofuran genotoxicity in vitro and in vivo are very scarce. There are few papers indicating that occupational exposure to this AChE inhibiting insecticide might be connected to increased risk of developing non-Hodgkin's lymphoma and lung cancer. Other authors showed its genotoxicity in vitro. We used comet and CBMN micronucleus assay combined with centromere probes to evaluate genome damage in lymphocytes of workers employed in carbofuran production. Also, the level of AChE activity in blood and plasma was measured. Only few workers exhibited AChE activity below 85%. Comet assay parameters were slightly but significantly elevated compared to control subjects, especially the long-tailed nuclei ratio. We found poor correlation between AChE activity and comet assay parameters, but significant effect of smoking and alcohol intake on the latest. In binucleated lymphocytes of workers significantly increased number of micronuclei, nuclear buds, and nucleoplasmic bridges was detected. Proportion of micronuclei with centromere, DAPI signal positive micronuclei was also elevated. Micronucleus assay parameters also appeared to be significantly influenced by duration of exposure to carbofuran. Together with published data on carbofuran's effect on health our results might indicate the need for further evaluations of its genotoxicity using a range of different cytogenetic techniques.

Approach for assessing total cellular DNA damage

The capability to relate phenotypic effects to damage associated with either the mitochondrial or nuclear genome is especially useful under a number of circumstances. Potential hazardous exposures can be evaluated for genotoxicity and related to diseases, particularly cancer. The correlation of DNA damage with adverse health effects is also important in evaluating the safety of various chemical agents and prospective therapeutics. Many techniques exist that afford the ability to identify and measure cellular DNA damage upon exposure to a suspected genotoxic agent; however, quite often these techniques are limited either by the advanced instrumentation and skill needed to perform the analyses or the amount of time needed and limited information obtained regarding the types of DNA damage generated. Recent advances in cellular-based methods have resulted in the timely and straightforward collection of reliable and specific data regarding levels of damage and the identity of the damage products. Antibodies developed for DNA damage lesions allow for the direct measurement of those lesions within a population of exposed cells, while the automation of the single-cell gel electrophoresis (comet) assay and the use of scoring software have led to rapid and standardized data collection. This essay describes the usefulness of these approaches, while providing a brief experimental overview of the techniques.