Mutagenesis, Vol. 16, No. 4, 359-363,
July 2001
© 2001 UK Environmental Mutagen Society/Oxford University Press
Chromosomal aberration and single cell gel electrophoresis (Comet) assay in the longitudinal risk assessment of occupational exposure to pesticides
Laboratory for Mutagenesis, Institute for Medical Research and Occupational Health, Ksaverska 2, 10000 Zagreb, Croatia
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Abstract |
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In recent years the use of pesticides in agriculture has been increasing steadily. At present there are more than 1000 chemicals classified as pesticides. Therefore, the widespread use of pesticides and their potential genetic hazard suggests that evaluation of their genotoxicity should be extended using the newer assays now available. In the present study chromosomal aberration analysis and the alkaline single cell gel electrophoresis (Comet) assay were used to evaluate the extent of DNA damage and DNA repair in peripheral blood lymphocytes of subjects employed in pesticide production. In order to determine possible primary genotoxic effects in workers blood samples were taken after an 8 month long period of exposure to a complex mixture of pesticides. To detect the possible occurrence of DNA repair in lymphocytes of the same subjects the second blood sample was taken after an 8 month long period of absence from the pesticide exposure zone. Regardless of the period of sampling, in the exposed group statistically significantly increased numbers of aberrant cells, chromatid and chromosome breaks, acentric fragments and dicentric chromosomes compared with the controls were found. After the workers had spent 8 months out of the pesticide exposure zone the number of aberrant cells and all types of chromatid and chromosome aberrations decreased significantly compared with sampling after the high exposure period, but it still remained significantly higher in comparison with the control group. After the period of high exposure to a mixture of pesticides statistically significantly increased levels of DNA damage in the Comet assay in terms of tail length and tail moment were found. After the workers were removed from production for 8 months both Comet assay end-points decreased significantly compared with the first sampling point, but they remained increased compared with the control.
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Introduction |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
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In recent years the use of pesticides in agriculture has been increasing steadily. At present there are more than 1000 chemicals classified as pesticides (Torres et al., 1992
). Because large amounts of these chemicals are released into the environment daily and many of them affect non-target organisms, they may represent a potential hazard to human health.
Occupational exposure to pesticides has been associated with several neoplastic diseases. In particular, a significant increase was found in the incidence of multiple myeloma (LaVechia et al., 1989; Brown et al., 1990), non-Hodgkin's lymphoma (Hoar et al., 1986; Cullen et al., 1990), Hodgkin's lymphoma (LaVechia et al., 1989), soft tissue sarcoma (Hardell and Sandstroem, 1979; Hardell and Erikson, 1988) and also lung (Blair et al., 1983), stomach, liver and bladder cancer (Stubbs et al., 1984) associated with pesticide exposure. A certain number of field studies have been done, obtaining an association between occupational exposure to complexes of pesticides and the presence of chromosomal aberrations as a factor which increases the risk of cancer (Nehez et al., 1981; Rita et al., 1987; Rupa et al., 1988, 1989; De Ferrari et al., 1991; Bolognesi et al., 1993; Garaj-Vrhovac and Zeljezic, 1999).
In the last few years the Comet assay has been applied in the evaluation of the possible genotoxic action of various pesticides (Ribas et al., 1995; Clements et al., 1997; Sasaki et al., 1997; Vigreux et al., 1998).
The widespread use of these chemicals and their potential genetic hazard suggests that the evaluation of their genotoxicity should be extended using the different assays available. In occupational exposures longitudinal studies involving repeated samplings from the same subjects can provide information on the kinetics of individual DNA damage.
In the present study chromosomal aberration analysis and alkaline single cell gel electrophoresis were used to evaluate the extent of DNA damage and DNA repair in peripheral blood lymphocytes of subjects employed in pesticide production. In order to determine possible primary genotoxic effects in workers blood samples were taken after an 8 month long period of exposure to a complex mixture of pesticides. To detect possible occurrence of DNA repair in lymphocytes of the same subjects a second blood sample was taken after an 8 month long period of absence from the pesticide exposure zone.
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Materials and methods |
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Subjects
Both chromosomal aberration analysis and Comet assay analysis were performed on blood samples of the two study groups. The first group consisted of workers employed in three different pesticide production units at the same time (the pesticide synthesis, concentrated emulsion production and powder and liquid pesticide production units). The average duration of their employment in pesticide production was 22.25 years (range 4–30 years). During production all subjects were simultaneously exposed to a complex mixture of pesticides (atrazine, alachlor, cyanazine, 2,4-dichlorophenoxyacetic acid and malathion) spending the same amount of time in each of the three production units. Production only occurs for 8 months of the year. During the next 8 months workers are transferred to jobs outside the pesticide exposure zone. For that reason two blood samples were taken from each individual: the first after the 8 month long period of daily exposure to pesticides spent actively working in pesticide production and a second after a period of no pesticide exposure, which means 8 months after the end of the production season. The control group was composed of persons chosen from the general population with no history of occupational exposure to either chemical or physical agents. For each control subject two blood samples were taken and the results are presented as the mean value of both sample analyses. The times of blood sampling were identical to those for the exposed group. The exposed subjects and the controls had not taken any medicines nor had they been exposed to any kind of radiation (diagnostic or therapeutic) for 12 months before blood sampling.
Demographic characteristics of both groups are shown in Table I.
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Methods
Venous blood was taken from each subject using heparinized syringes. Immediately after sampling the blood was put on ice and brought to the laboratory for analysis. The same blood sample was analyzed using both methods: chromosomal aberration analysis and the Comet assay.
For chromosomal aberration analysis whole blood samples were cultivated in F-10 medium (Sigma) at 37°C in the presence of 0.5 ml of phytohemagglutinin (Murex), 20% fetal bovine serum (Biological Industries, Israel), 5000 IU/ml penicillin and 1000 IU/ml streptomycin.
For analysis of chromosomal aberrations lymphocytes were grown for a total of 48 h, in the presence of 0.2 µg/ml colchicine (Sigma) for the last 3 h. Fixation of the cells and preparation of chromosomes were carried out according to the conventional method (IAEA, 1986). For each subject 200 metaphases were examined. The analysis of structural aberrations included chromatid and chromosome breaks, appearance of acentric fragments, dicentric chromosomes and chromatid exchanges (tetraradius forms). Cells containing any of these types of chromosomal alterations were considered aberrant cells. The results are presented as total number of each type of damage per subject examined.
The Comet assay was conducted under alkaline conditions according to Singh et al. (1988). All chemicals used to perform the Comet assay were obtained from Sigma. Two microliters of whole blood were suspended in 0.5% low melting point agarose and sandwiched between a layer of 0.6% normal melting point agarose and a top layer of 0.5% low melting point agarose on fully frosted slides. During polymerization of each gel layer the slides were kept on ice. After solidification of the 0.6% agarose layer the slides were immersed in lysis solution (1% sodium sarcosinate, 2.5 M NaCl, 100 mM Na2EDTA, 10 mM Tris–HCl, 1% Triton X-100 and 10% DMSO) at 4°C. After 1 h slides were placed in electrophoresis buffer (0.3 M NaOH, 1 mM Na2EDTA, pH 10) for 20 min at room temperature to allow for DNA unwinding. Electrophoresis was conducted in a horizontal electrophoresis platform in fresh, chilled electrophoresis buffer for 20 min at 300 mA and 19 V. The slides were neutralized with Tris–HCl buffer, pH 7.5, three times for 5 min and stained with 10% ethidium bromide for 10 min. Each slide was analyzed using a Leitz Orthoplan epifluorescence microscope equipped with a 515–560 nm excitation filter. For each subject 50 cells were analyzed with an automatic digital analysis system, Comet assay II (Perceptive Instruments, Halstead, UK), determining tail length and tail moment (tail lengthx% tail DNA/100).
Statistics
Possible differences in chromosomal aberration analysis and Comet assay end-points between the control and exposed groups were evaluated using the Mann–Whitney U-test. In order to compare the variation in end-points of two blood samples of exposed subjects Wilcoxon matched pairs test was used.
In addition, to assess the statistical significance of confounding factors (age, gender and smoking), a multivariate analysis of variance was conducted.
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Results |
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Results of the analysis of structural chromosomal aberrations are shown in Tables II and III
. Regardless of the point of sampling, in the exposed group a statistically increased number of aberrant cells, chromatid and chromosome breaks, acentric fragments and dicentric chromosomes was found compared with the control. Chromatid exchanges were found only in the exposed group after the workers had spent 8 months in daily pesticide production. After the workers had spent 8 months out of the pesticide exposure zone all types of chromatid and chromosome aberrations significantly decreased compared with the sampling after the high exposure period, but it still remained significantly higher in comparison with the control group. So, the mean value of the total number of aberrations found in the control group was 1.02 ± 0.77, whereas in the exposed group after the period of high pesticide exposure it was 6.7 ± 1.75 and after the period of no exposure it was 0.76 ± 1.16. A multivariate analysis of variance showed that age, gender and smoking did not affect between-group variations in the number and type of structural aberrations. Also, no significant differences in the numbers of aberrations with regard to subject gender and smoking habit were found.
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The effects of pesticide exposure on the extent of DNA migration are presented in Tables IV and V
. After the period of high exposure to the mixture of pesticides significantly increased levels of DNA damage in terms of tail length and tail moment were found. After the workers were removed from production for 8 months both Comet assay end-points significantly decreased compared with the first sampling point. Nevertheless, at the second sampling point both tail length and tail moment still remained significantly increased compared with the control.
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In Table IV
the distributions of tail lengths and tail moments are shown. Distribution of both Comet assay end-points appeared to be wider after the workers had spent 8 months in pesticide production compared with the controls, as well as with the sampling after the no exposure period. For the first sampling point values of tail lengths ranged from 16 to 95 µm, whereas the values of tail moments ranged from 11 to 85. After the workers were removed from the exposure zone values of tail lengths of lymphocyte DNA varied between 11 and 30 µm. The tail moment values of the same blood sample varied between 6 and 25. At both blood sampling points values of tail lengths for the control subjects were from 6 to 20 µm and tail moments from 5 to 15. The multivariate analysis of variance showed that age, gender and smoking did not affect between-group variations in the Comet assay parameters. Nevertheless, in the smokers control group and the exposed group after the workers had spent 8 months in pesticide production a statistically significantly increased level of DNA migration was found. We also found a statistically significant difference in the Comet assay parameters between males and females of the exposed group after the pesticide exposure period. |
Discussion |
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Results of the chromosomal aberration analysis presented in this study suggest that long-term occupational exposure to a mixture of pesticides (atrazine, alachlor, cyanazine, 2,4-dichlorophenoxyacetic acid and malathion) could cause a significant increase in the level of DNA damage. A significant increase in the number of both chromatid and chromosomal types of aberrations found in the group of workers after the period of pesticide production suggests that a mixture of pesticides could express clastogenic activity. This finding is supported by the appearance of dicentric chromosomes and chromatid exchanges as complex aberrations that were not detected in the control subjects. Although chemical agents mostly lead to the appearance of chromatid aberrations, there is evidence that, due to their structure, some of them could also induce chromosome types of aberrations, as shown in the present study (Obe and Beck, 1982
; IAEA, 1986; Carrano and Natarajan, 1988). The chromosome types of aberrations could also arise due to misrepair of lesions in the G0 stage of circulating lymphocytes as well as derived aberrations from precursor cells in bone marrow and thymus, as suggested by Carrano and Natarajan (1988).
After the workers had spent 8 months out of pesticide production both chromatid and chromosomal types of aberration significantly decreased compared with the first sampling time. Furthermore, in the lymphocytes of workers no chromatid exchanges were detected after the no exposure period. These results are in agreement with those obtained by Van Bao et al. (1974), Mustonen et al. (1986), Paldy et al. (1987), De Ferrari et al. (1991), Carbonell et al. (1995) and Kourakis et al. (1996). According to Carrano and Natarajan (1988), there are short-lived and long-lived lymphocytes. Short-lived lymphocytes may exist for several years while long-lived lymphocytes have been found to exist for decades. Because in the bloodstream the majority of lymphocytes are in the G0 stage, the frequency of chromosomal aberrations remains at the same level even many years after exposure. In the case of chemical-induced lesions the cells must go through an S phase in order to be transformed into aberrations, which does not take place until the cells are stimulated with mitogen in vitro, allowing a considerable time for repair of the lesion. So, detected decreases in chromosomal aberrations could result from various independent events. Lymphocytes expressing high levels of DNA damage could die because of high genomic instability and/or the majority of the DNA damage could be efficiently repaired during these 8 months of non-exposure. An additional reduction in number of cells carrying chromosomal aberrations could be obtained by production of undamaged lymphocytes from the stem cell pool (Obe and Beck, 1982; IAEA, 1986; Carrano and Natarajan, 1988). The finding that in three subjects occupationally exposed to pesticides dicentric chromosomes were detected both after pesticide production and after the no exposure period could be explained by the clastogenic action of pesticides on precursor cells in bone marrow and thymus (Carrano and Natarajan, 1988).
Nevertheless, an 8 month long period of non-exposure was not long enough for all chromosomal aberrations to be efficiently repaired. Furthermore, some new aberrations might be introduced by misrepair of primary lesions. Both these findings resulted in a significantly increased number of aberrations at the second sampling point compared with the control.
In the present study we were unable to detect significant differences in the numbers of chromosomal aberrations related to smoking habit or gender of the subjects, which is in agreement with the results of many other authors (Paldy et al., 1987; De Ferrari et al., 1991; Carbonell et al., 1995). Namely, with regard to an elementary concept in statistics, even if the groups of subjects are `perfectly representative' these effects will not be statistically significant if the sample is small (three females and six non-smokers in the control group).
The results of the Comet assay presented in this study confirm the ability of a mixture of pesticides (atrazine, alachlor, cyanazine, 2,4-dichlorophenoxyacetic acid and malathion) to cause a significant increase in the level of DNA damage. This finding is supported by the work of Fairbairn et al. (1995) and Shah et al. (1997) showing that pesticides could induce types of DNA damage that could be detected by the Comet assay. Some other authors were also able to demonstrate a genotoxic effect of various pesticides by the Comet assay (Ribas et al., 1995; Clements et al., 1997; Vigreux et al., 1998). DNA damage detected in the present study and measured as Comet assay end-points could possibly originate from DNA single-strand breaks, repair of DNA double-strand breaks, DNA adduct formation or DNA–DNA and DNA–protein crosslinks (King et al., 1993; Fairbairn et al., 1995; Shah et al., 1997). A significant decrease in the tail length and tail moment values measured after the 8 month long non-exposure period could be due to repair of the majority of the DNA damage, death of highly damaged cells and dilution of cells carrying DNA damage by the production of undamaged lymphocytes from the stem cell pool. In spite of these three processes, lymphocytes of workers at the second sampling point manifested a significantly higher amount of DNA damage measured by both Comet assay end-points compared with the control. This finding suggests that not all DNA damage was repaired and that some new DNA lesions might be induced by misrepair.
As shown in Table V, we were able to find a significantly higher DNA migration level in smokers of the control group as well as in the exposed group after the period of pesticide production, which correlates with results obtained by Frenzilli et al. (1997), Sardas et al. (1995) and Betti et al. (1994, 1995). In contrast, no differences between Comet assay end-points of smokers and non-smokers were detected at the second sampling point, which agrees with the results of Wojewodzka et al. (1999), which could be a consequence of the introduction of a large amount of DNA damage in the genome due to pesticide exposure. As for the chromsomal aberration analysis, due to the small proportion of females in the control group it was not possible to determine differences in the level of DNA damage with regard to gender of the subject. In the exposed group the proportion of female subjects was larger (eight females) than in the control group (three females) and also the females of the exposed group were mostly non-smokers, so it was possible to detect differences in the Comet assay end-points between males and females. Due to intensive changes in the lymphocyte pool during the 8 months of non-exposure (death of highly damaged cells and production of undamaged lymphocytes from the stem cell pool) the differences in the Comet assay parameters between exposed smokers and exposed non-smokers might be lost at the second sampling point.
According to the results shown in Table IV the distribution of tail length and tail moment is much wider in the lymphocytes of the exposed subjects for the first sampling point compared with the control and exposed subjects at the second sampling point. Some of these comets differ in the values of both end-points by a factor of two. As suggested by Fairbairn et al. (1995), it could be due to the appearance of some sub-populations of lymphocytes resistant to pesticide genotoxicity.
The results presented in this study stress the necessity of a further more detailed testing of pesticide genotoxicity. They also point out the need for permanent biomonitoring of subjects occupationally exposed to various mixtures of pesticides, in order to detect early cytogenetic biomarkers of exposure and to prevent further induction of DNA lesions which could induce neoplastic growth of damaged somatic cells.
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Acknowledgments |
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This research was supported by the Ministry of Science and Technology of the Republic of Croatia (00220107).
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Notes |
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1 To whom correspondence should be addressed. Tel: +385 1 4673 188; Fax: +385 1 4673 303; Email: dzeljezi{at}imi.hr
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References |
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Betti,C., Davini,T., Giannessi,L., Loprieno,N. and Barale,R. (1994) Microgel elelctrophoresis assay (comet test) and SCE analysis in human lymphocytes from 100 normal subjects. Mutat. Res., 307, 323–333.[Web of Science][Medline]
Betti,C., Davini,T., Giannessi,L., Loprieno,N. and Barale,R. (1995) Comparative studies by comet test and SCE analysis in human lymphocytes from 200 healthy subjects. Mutat. Res., 343, 20–207.
Blair,A., Grauman,D.J., Lubin,J.H. and Fraumeni,J.F. (1983) Lung cancer and other causes of death among licensed pesticide applicators. J. Natl Cancer Inst., 71, 31–37.
Bolognesi,C., Parrini,M., Bonassi,S., Ianello,G. and Salanitto,A. (1993) Cytogenetic analysis of human population occupationally exposed to pesticides. Mutat. Res., 285, 239–249.[Web of Science][Medline]
Brown,L.M., Blair,A., Gibson,R., Everett,G.D., Cantor,K.P., Schuman,L.M., Burmeister,L.F., Van Lier,S.F. and Dick,F. (1990) Pesticide exposures and other agricultural risk factors for leukemia among men in Iowa and Minnesota. Cancer Res., 50, 6585–6591.
Carbonell,E., Valbuena,A., Xamena,N., Creus,A. and Marcos,R. (1995) Temporary variations in chromosomal aberrations in a group of agricultural workers exposed to pesticides. Mutat. Res., 344, 127–134.[Web of Science][Medline]
Carrano,A.V. and Natarajan,A.T. (1988) Consideration for population monitoring using cytogenetic techniques. Mutat. Res., 204, 379–406.[Web of Science][Medline]
Clements,C., Ralph,S. and Petras,M. (1997) Genotoxicity of selected herbicides in Rana catesbeiana tadpoles using alkaline single-cell gel DNA electrophoresis (comet) assay. Environ. Mol. Mutagen., 29, 277–288.[Web of Science][Medline]
Cullen,M.R., Cherniack,M.G. and Rosenstock,L. (1990) Occupational medicine. N. Engl. J. Med., 322, 675–682.[Web of Science][Medline]
De Ferrari,M., Artuso,M., Bonassi,S., Bonatti,S., Cavalieri,Z., Pescatore,D., Marchini,E., Pisano,V. and Abbondandolo,A. (1991) Cytogenetic biomonitoring of an Italian population exposed to pesticides: chromosome aberration and sister-chromatid exchange analysis in peripheral blood lymphocytes. Mutat. Res., 260, 105–113.[Web of Science][Medline]
Fairbairn,D.W., Olive,P.L. and O'Neill,K.L. (1995) The comet assays: a comprehensive review. Mutat. Res., 339, 37–59.[Web of Science][Medline]
Frenzilli,G., Betti,C., Davini,T., Desideri,M., Fornai,E., Giannessi,L., Maggiorelli,F., Paoletti,P. and Barale,R. (1997) Evaluation of DNA damage in leukocytes of ex-smokers by single cell gel electrophoresis. Mutat. Res., 275, 117–123.
Garaj-Vrhovac,V. and Zeljezic,D. (1999) Chromosomal aberrations and frequency of micronuclei in workers employed in pesticide production. Biologia, 54, 707–712.
Hardell,L. and Eriksson,M. (1988) The association between soft-tissue sarcomas and exposure to phenoxyacetic acids. A new case-referent study. Br. J. Cancer, 62, 652–656.
Hardell,L. and Sanstroem,A. (1979) Case-control study: soft tissue sarcomas and exposure to phenoxyacetic acids or chlorophenols. Br. J. Cancer, 39, 711–717.[Web of Science][Medline]
Hoar,S.K., Blair,A. and Holmes,F.F. (1986) Agricultural herbicide use and risk of lymphoma and soft tissue sarcoma. J. Am. Med. Assoc., 256, 1141–1147.
IAEA (1986) Biological Dosimetry: Chromosome Aberration Analysis for Dose Assessment, Technical Reports Series no. 260. International Atomic Energy Agency, Vienna, Austria, pp. 59–63.
King,J.S., Valgargel,E.R., Rufer,J.T., Phillips,J.W. and Moran,W.F. (1993) Non-complementary DNA double strand break rejoining in bacterial and human cells. Nucleic Acids Res., 21, 1055–1059.
Kourakis,A., Mouratidou,M., Barbouti,A. and Dimikiotou,M. (1996) Cytogenetic effects of occupational exposure in the peripheral blood lymphocytes of pesticide sprayers. Carcinogenesis, 17, 99–101.
LaVechia,C., Negri,E., d'Avanzo,B. and Francheschi,S. (1989) Occupation and lymphoid neoplasms. Br. J. Cancer, 60, 385–388.[Web of Science][Medline]
Mustonen,R., Kangas,J., Vuojolahti,P. and Linnainmaa,K. (1986) Effects of phenoxyacetic acids on the induction of chromosome aberrations in vitro and in vivo. Mutagenesis, 1, 241–245.
Nehez,M., Berencsi,G. and Paldy,A. (1981) Data of the chromosomal aberrations of workers exposed to pesticides. Regul. Toxicol. Pharmacol., 1, 116–122.
Obe,G. and Beck,B. (1982) The human leukocyte test system. In De Serres,F.J. and Hollaender,A. (eds), Chemical Mutagens. Plenum Press, New York, NY, Vol. 7, pp. 337–400.
Paldy,A., Puskas,N., Vincze,K. and Hadhazi,M. (1987) Cytogenetic studies on rural population exposed to pesticides. Mutat. Res., 187, 127–132.[Web of Science][Medline]
Ribas,G., Frenzilli,G., Barale,R. and Marcos,R. (1995) Herbicide-induced DNA damage in human lymphocytes evaluated by the single-cell gel electrophoresis (SCGE) assay. Mutat. Res., 344, 41–54.[Web of Science][Medline]
Rita,P., Reddy,P.P. and Reddy,S.V. (1987) Monitoring of workers occupationally exposed to pesticides in grape gardens of Andhra Pradesh. Environ. Res., 44, 1–5.[Medline]
Rupa,D.S., Rita,P., Reddy,P.P. and Reddi,O.S. (1988) Screening of chromosomal aberrations and sister chromatid exchanges in peripheral lymphocytes of vegetable garden workers. Hum. Toxicol., 7, 333–336.[Web of Science][Medline]
Rupa,D.S., Reddy,P.P. and Reddi,O.S. (1989) Frequencies of chromosomal aberrations in smokers exposed to pesticides in cotton fields. Mutat. Res., 222, 37–44.[Web of Science][Medline]
Sardas,S., Walker,D., Akyol,D. and Karakaya,A.E. (1995) Assessment of smoking mothers on newborn infants using alkaline single-cell gel electrophoresis technique. Mutat. Res., 335, 213–217.[Web of Science][Medline]
Sasaki,Y.F., Nishidate,E., Izumiyama,F., Matsusaka,N. and Tsuda,S. (1997) Simple detection of chemical mutagens by alkaline single-cell gel electrophoresis (comet) assay in multiple mouse organs (liver, lung, spleen, kidney and bone marrow). Mutat. Res., 391, 215–231.[Web of Science][Medline]
Shah,R.G., Lagueux,J., Kapur,S., Levallois,P., Ayotte,P., Tremblay,M., Zee,J. and Poirier,G.G. (1997) Determination of genotoxicity of the metabolites of pesticides guthion, sencor, lorox, reglone, daconil and admire by 32P-postlabeling. Mol. Cell. Biochem., 169, 177–184.[Web of Science][Medline]
Singh,N.P., McCoy,M.T., Tice,R.R. and Schneider,E.L. (1988) A simple technique for quantitation of low levels of DNA damage in individual cells. Exp. Cell Res., 175, 184–191.[Web of Science][Medline]
Stubbs,H. A., Harris, J. and Spear,R. C. (1984) A proportionate mortality analysis of California agricultural workers. Am. J. Ind. Med., 6, 305–320.[Web of Science][Medline]
Torres,C., Ribas,G., Xamena,N., Creus,A. and Marcos,R. (1992) Genotoxicity of four herbicides in the Drosophila wing spot. Mutat. Res., 280, 291–295.[Web of Science][Medline]
Van Bao,T., Szabo,I., Ruziczka,P. and Czeizel,A. (1974) Chromosome aberrations in patients suffering acute organic phosphate insecticide intoxication. Humangenetik, 24, 33–57.[Web of Science][Medline]
Vigreux,C., Poul,J.M., Deslandes,E., Lenailly,P., Godard,T., Sichel,F., Henryamar,M. and Gauduchon,P. (1998) DNA damaging effects of pesticides measured by single cell electrophoresis assay (comet assay) and the chromosomal aberration test, in CHOK1 cells. Mutat. Res., 419, 79–90.[Web of Science][Medline]
Wojewodzka,M., Kurszewski,M., Iwanenko,T., Collins,A.R. and Szumiel,I. (1999) Lack of adverse effect of smoking habit on DNA strand breakage and base damage, as revealed by the alkaline comet assay. Mutat. Res., 440, 19–25.[Web of Science][Medline]
Received on February 6, 2001; accepted on April 9, 2001.
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