Toxicidade ao trato digestório associada à exposição ao herbicida ácido diclorofenóxiacético (2,4-D) em ratos

Abstract

Introduction: The dichlorophenoxyacetic herbicide (2,4-D) is a synthetic auxin of the of chlorophenoxy acidic herbicides class, and was the first selective herbicide developed to control dicot plants or broadleaf plants, crop leaves and weeds. It is one of the most used herbicides in the world due to its general applicability and low cost. People can be exposed to 2,4-D through skin contact, ingestion or inhalation and damage to that exposure. There is no evidence to determine whether there is an association between exposure to 2,4-D and gastrointestinal disorders. Objective: The objective of this study was to evaluate the possible damage to the digestive tract through chronic oral and inhalation exposure to the herbicide 2,4-D in rats. Material and methods: Eighty male and adult albino Wistar rats were divided into 8 groups (n = 10): I - Inhalation control group: exposed to nebulization with distilled water; O - Oral control group: received nebulized feed with distilled water; 2,4-D LI - Group exposed to low concentration of 2,4-D by inhalation; 2,4-D LO - Group exposed to low concentration of 2,4-D orally; 2,4-D MI - Group exposed to the average concentration of 2,4-D by inhalation; 2,4-D MO - Group exposed to the average concentration of 2,4-D orally; 2,4-D HI - Group exposed to high concentration of 2,4-D by inhalation; 2,4-D HO - Group exposed to high concentration of 2,4-D orally. Three concentrations were used according to the recommendation described in the product insert: 3.71 x 10-3 grams of active ingredient per hectare (g.a.i. / ha) of 2,4-D, considered low concentration; 6.19 x 10-3 g.a.i. / ha of 2,4-D, considered medium concentration; and 9.28 x 10-3 g.a.i. / ha of 2,4-D, considered high concentration. The animals were exposed for 6 months. Esophagus, stomach and small and large intestine were collected for histopathological analysis. Results: One animal in the 2,4-D HO group died during the study due to ear canal infection. There was no difference in the animals' weight and feed consumption during the experiment between the study groups (p> 0.05). Hyperkeratosis was observed in most animals exposed to 2,4-D and was independent of the exposure route (oral or inhaled) (p <0.05). No gastric changes were observed in any of the animals evaluated. Only animals exposed to medium and high concentration of 2,4-D, presented dysplasia in both the small and large intestines (p <0.05) and this was mild in all cases. Conclusion: Chronic exposure to 2,4-D, regardless of the route and concentration of exposure, causes damage to the esophagus and medium and high concentrations have carcinogenic potential for the intestine.