Evaluation of the pulmonary epithelium in rats treated with malathion

Abstract

Objective – To analyze alterations in the pulmonary epithelium of rats subjected to oral administration of the insecticide Malathion through histopathological analysis.

Methodology – Thirty female Wistar rats, initially aged 21 days, from the Central Animal Facility of the State University of Londrina – UEL, Protocol CEUA-7109, were used. The animals were randomly distributed into three experimental groups (n = 10). Two groups were treated with Malathion at doses of 10 mg/kg or 50 mg/kg of body weight. These doses correspond to 0.5% and 2.5%, respectively, of the oral LD50 for rats (oral LD50 = 2000 mg/kg). The other group (control group) received only the vehicle (soybean oil) in an equal volume. Results are presented as mean (standard deviation), p<0.05, two-factor ANOVA test.

Originality/Relevance – The originality of this article lies in the scarcity of histopathological studies on the effects of Malathion on pulmonary epithelium, especially with a morphometric focus in animal models, contributing to the understanding of respiratory toxic impacts of organophosphate insecticides.

Results – The results were obtained through histopathological analysis. Although there was an increase in goblet cells in the M50 group, the values were not significant due to similar means. Regarding bronchiole area, a significant increase was observed when comparing the control group with M10. For the lumen area, no major differences were observed among group means, although the M50 group showed a reduction. An increase in muscle layer thickness and inflammation score was noted in the M50 group.

Theoretical/Methodological Contributions – The study contributes to improving the understanding of pulmonary toxicity mechanisms induced by organophosphates, and supports the use of histopathological and morphometric analysis as effective approaches to assess structural changes in respiratory tissues exposed to agrochemicals.

Social and Environmental Contributions – The findings highlight respiratory risks associated with Malathion exposure, reinforcing the need for public policies aimed at regulating pesticide use and protecting exposed populations, thus promoting safer and more environmentally responsible agricultural practices.