Comparison of inhalation and oral exposure to the glyphosate herbicide: effects on respiratory system in rats

Abstract

Despite authorized use in Brazilian agriculture, there is little research on the impact of the glyphosate on human health. Recent studies have linked its intake to toxic and respiratory syndromes. The aim of this research is to compare the effects of inhalation with the ingestion of glyphosate on the respiratory system of rats. For this, 80 Wistar rats were used, divided into groups chronically exposed to different concentrations of glyphosate: Inhalatory and Oral Control (ICG and OCG), Low Inhalatory and Oral Concentration (LICG and LOCG), Average Inhalatory and Oral Concentration (AICG and AOCG) and High Inhalatory and Oral (HICG and HOCG). After euthanizing these animals, slides were made with hematoxylin-eosin and PAS-Alcian of the lungs for histopathological evaluation of airway morphology and inflammation. The collected data were analyzed statistically with the aid of the Sigma Stat® 2.0 program, using the variance tests followed by Tukey, or the Kruskal-Wallis tests followed by Dunn. p value less than 0.05 was considered significant. In the control groups, the wall thickness and airway area were significantly higher in OCG. In low concentration, wall thickness was greater in LOCG and inflammation was more intense in LICG. The mean concentration resulted in a greater amount of calyx cells, wall thickness, area, and inflammation at AOCG. In high concentration, the wall thickness was higher in the HOCG. In view of more significant changes in oral exposure to a mean concentration of glyphosate, it is possible to suggest that the systemic impact of ingestion is greater than the pulmonary damage by inhalation.