نشانگرهای سمیت ژنی و استرس اکسیداتیو در کشاورزان قرار گرفته در معرض آفت کش ها Markers of genotoxicity and oxidative stress in farmers exposed to pesticides

1. Introduction Many in vitro and in vivo studies, as well as epidemiological approaches, have demonstrated the ability of certain pesticides to produce genomic toxicity. This genotoxicity is considered a primary risk factor that will trigger effects over the years, such as carcinogenic, neurological and reproductive processes, due to frequent exposures. Genetic alterations may occur due to mutagenic and non-mutagenic processes, caused by the use of pesticides. Some studies have shown a strong relationship between occupational exposure and some proto-oncogenes in the exposed populations, due to the cytogenetic effects of pesticides (Bolognesi et al., 2011; George and Shukla, 2011). It is attributed a higher frequency of cancer risk involving the brain, skin, esophagus, lung, kidney, bladder, prostate, testis, thyroid, cervix, rectum and soft tissues, as well as leukemia and non-Hodgkin’s lymphoma (Blair and Freeman, 2009). Due to the evidence of carcinogenic effects caused by pesticides and the frequency of increased risk in the development of malignancies in occupationally exposed populations, there is a growing need for studies of these populations (Singh et al., 2011). Cytogenetic methods, including the quantification of micronucleus, have been widely used for the biological monitoring of populations exposed to mutagenic and carcinogenic agents (da Silva, 2016). Micronuclei (MNi) are acentric fragments or complete chromosomes that do not bind to the mitotic spindle during cytokinesis and are excluded from the nuclei. Different mechanisms may be involved in the formation of micronucleus (Heddle et al., 1983; Tucker and Preston, 1996), including chromosome rupture (clastogenesis) and spindle rupture (aneugenesis). The comet assay provides a rapid method for quantitatively assessing DNA damage in isolated cells. This method is based on the electrophoresis of incorporated cells and lysed on agarose on a microscope slide. The underlying mechanism is based on the organization of DNA in large coiled structures that can be relaxed by electrophoresis by breaks of ribbons, forming a comet tail like effect. Since the comet method is a relatively simple, inexpensive and rapid technique that can be performed using samples obtained from in vitro or in vivo studies, the assay is suitable for use in biomonitoring of farmers exposed to genotoxic hazards (Kaur et al., 2011). Under alkaline conditions, the comet assay detects cleavages of DNA strands and labile alkaline sites (Singh et al., 1988).