Genotoxicidade associada à exposição crônica a herbicida a base de glifosato em ratos

Abstract

Although studies carried out by the industry suggest that glyphosate is not very toxic to non-target species, studies carried out with this herbicide cast doubt on its safety for the health of other species. The aim of this study was to evaluate the genotoxicity of chronic oral and inhalation exposure to the herbicide glyphosate in rats. For the accomplishment of the experiments, 88 male, adult, albino Wistar rats were used, divided into nine groups: CI - Inhalation Control Group: animals exposed to nebulization with distilled water (n=10); CO - Oral Control Group: nebulized diet with distilled water (n=10); BI - Low Inhalation Concentration Group: animals exposed to nebulization to the herbicide with 2.99 x 10-3 grams of active ingredient per hectare (g.i.a/ha) (n=10); BO - Low Oral Concentration Group: nebulized feed with the herbicide at a concentration of 2.99 x 10-3 g.i.a/ha (n=10); MI - Medium Inhalation Concentration Group: animals exposed to nebulization to the herbicide with 4.99 x 10-3 g.i.a/ha (n=10); OM - Medium Oral Concentration Group: feed sprayed with the herbicide at a concentration of 4.99 x 10-3 g.i.a/ha (n=10); AI - High Inhalation Concentration Group: animals exposed to nebulization to the herbicide with 7.48 x 10-3 g.i.a/ha (n=10); AO - High Concentration Group: ration sprayed with the herbicide at a concentration of 7.48 x 10-3 g.i.a/ha (n=10); positive control (PC) (n=8), whose animals received cyclophosphamide in a single dose on the first day of the experiment and were euthanized 24 hours later. Bone marrow cells were collected for the micronucleus test and for the comet assay. The remaining animals were euthanized 6 months after the beginning of the experiment. The median of micronuclei in the inhaled and oral control groups was 0, in the BI group 4.5, in the BO of 1.5, in the MI of 5, in the MO of 1, in the AI of 5, in the AO of 3, and in the positive control group of 9. There was a difference between the studied groups (p< 0.0001). Regarding the route of exposure, the animals exposed by inhalation had a higher number of micronuclei than those exposed orally (p< 0.0001). In the comet assay, while the control groups had a higher number of cells with damage class 0, the animals exposed to GBH had a greater number of cells with damage class 4, especially those exposed to high concentrations (p<0.05). We conclude that inhalation exposure to GBH leads to greater micronucleus formation, and exposures to higher concentrations present greater DNA damage at the single-cell level, evidenced by the comet assay.