RESUMO Os agricultores envolvidos na colheita do tabaco estão regularmente expostos a grande quantidade de agroquímicos. Para determinar como esta exposição a pesticidas induz alterações genéticas nestes agricultores, amostras de sangue foram obtidas de 77 indivíduos expostos e de 60 indivíduos não expostos. O dano ao DNA foi analisado pelo Ensaio Cometa e pelo Teste de Micronúcleos (MN). A capacidade antioxidante foi avaliada pela atividade da enzima superóxido dismutase (SOD), e a influência do polimorfismo do gene PON1 foi usada como um biomarcador de susceptibilidade. O teor de elementos inorgânicos foi determinado nas amostras de sangue pela análise PIXE. Nossos resultados mostraram que a freqüência de danos, índice de danos, freqüência de MN e a atividade da SOD foram significativamente mais elevados no grupo exposto em relação ao não exposto. O gene PON1 demonstrou influenciar a frequência de MN observada no grupo exposto. As concentrações de elementos inorgânicos foram maiores no grupo exposto em relação ao não exposto. Neste estudo observamos que danos genéticos e alterações no balanço oxidativo foram induzidos pela exposição dos agricultores a misturas complexas de pesticidas na presença de componentes inorgânicos, e pelas quais a influência do genótipo foi evidente.

ABSTRACT 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.

Farm workers are often exposed to pesticides, which are products belonging to a specific chemical group that affects the health of agricultural workers and is mostly recognized as genotoxic and carcinogenic. The exposure of workers from Piauí, Brazil, to these hazardous chemicals was assessed and cytogenetic alterations were evaluated using the buccal micronucleus assay, hematological and lipid parameters, butyrylcholinesterase (BChE) activity and genetic polymorphisms of enzymes involved in the metabolism of pesticides, such as PON1, as well as of the DNA repair system (OGG1, XRCC1 and XRCC4). Two groups of farm workers exposed to different types of pesticides were evaluated and compared to matched non-exposed control groups. A significant increase was observed in the frequencies of micronuclei, kariorrhexis, karyolysis and binucleated cells in the exposed groups (n = 100) compared to controls (n = 100). No differences were detected regarding the hematological parameters, lipid profile and BChE activity. No significant difference was observed either regarding DNA damage or nuclear fragmentation when specific metabolizing and DNA repair genotypes were investigated in the exposed groups.

Our mutagenesis group has been studying with important economic drivers of our state, such as agriculture, the footwear 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.

Gene polymorphisms involved in the metabolism of drugs and chemical carcinogens seem to be responsible for differences in the susceptibility of individuals to cancer, but genetic population studies are needed to characterize these polymorphisms in different ethnic populations. We investigated polymorphisms of the cytochrome P450 (CYP) gene CYP1A1 and the glutathione S-transferase (GSTs) genes GSTM1, GSTT1 and GSTP1 in a sample of Afro-Brazilians from the southern Brazilian city of Porto Alegre to verify if there were ethnic differences compared to the polymorphisms of the same genes in a previously described sample of Brazilians of European descent from the same city. The allele frequencies detected in the Afro-Brazilian population investigated in this study were CYP1A1*2A (30%) and GSTP1*Val (42%) while the frequency of the GSTM1 null genotype was 34% and that of the GSTT1 null genotype was 28%. Significant differences in genotype distribution and allelic frequencies were detected between Brazilians of African and of European descent from Porto Alegre in terms of the polymorphisms CYP1A1*2A (p = 0.003), GSTP1-Ile105Val (p = 0.002) and the GSTM1 null genotype (p = 0.01) but there was no detectable significant difference in respect to GSTT1 null genotype frequencies.

We investigated the polymorphic tetranucleotide repeat (TTTA)n located in the fourth intron of the CYP19 gene in two Brazilian populations. The frequencies of the five common alleles (A) in Euro- and Afro-Brazilians were, respectively: seven repeats (A5), 0.586 and 0.80; eight repeats (A4), 0.092 and 0.06; nine repeats (A3), 0.014 and 0.01; eleven repeats (A2), 0.284 and 0.09; twelve repeats (A1), 0.021 and 0.04. In addition, one Euro-Brazilian individual had a rare allele with 13 repeats. The allelic frequencies in Euro- and Afro-Brazilians differed statistically (p < 10-3). The two samples were found to be in Hardy-Weinberg equilibrium (p = 0,828 and p = 0,995).