Análise histopatológica em ratos expostos cronicamente por via inalatória ao herbicida Ácido 2,4-Diclorofenoxiacético (2,4-D)

Abstract

One of the most used means for the application of pesticides is aerial spraying, despite the already known risks that this technique can bring, mainly due to the existence of technical drift. Agricultural pesticides can cause acute, subacute and chronic intoxications. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the first herbicides formulated and one of the most used to date, in the control of several weed plants, in cereal plantations, sugarcane plantations, forest control and orchards. The objective of the study was to evaluate nasopharyngeal epithelium and the hematological profile of rats submitted to chronic spraying of 2,4-D herbicide. Fourty male Wistar rats were divided into four groups: Control Group (GC), Low Concentration Group (GBC), Medium Concentration Group (GMC) and High Concentration Group (GAC). The animals were exposed from Monday to Friday, through 2 boxes attached to nebulizers, one box for the control group and the other for groups exposed to 2,4-D, which were responsible for spraying the different concentrations of herbicide for a period of 15 minutes daily for 6 consecutive months. After the exposure period, the blood sample was collected for the hemogram and the nasal epithelium was collected and analyzed by quantification of the mast cells and inflammatory infiltrate. It was observed that there was a statistically significant difference only in the haematological parameter Average Corpuscular Hemoglobin Concentration (CHCM) of the GBC when compared to the GC, but the GBC was with CHCM values within the reference values and the GC was high. Regarding the other hematological parameters, quantification of the mast cells and the inflammatory infiltrate, there was no statistically significant difference of any group exposed to the 2,4-D herbicide compared to the CG. Therefore, 2,4-D herbicide did not demonstrate toxicity to the haematological parameters and nasal epithelium of Wistar rats after chronic inhalation exposure in the 6-month period, compared to the control group, in agreement with the toxicological classification of the herbicide published Agency of Environmental Protection of the United States (EPA). It should be noted that the toxic effects need to be evaluated with research in longer periods of time than the present study.