Acute Oral Toxicity and Histopathological Studies of Ethion, an Organophosphate Pesticide, in Adult Female Rats

Background: Ethion, an OP pesticide commonly utilized in citrus fruits, vegetables, and tea plantations, has become a concern due to its overuse and unregulated application across various crops. Objectives: The main objective of this study was to determine the median lethal dose (LD 50 ) of ethion, an organophosphate pesticide (OP), in adult female rats, employing the Miller and Tainter method. Materials and Methods: Various doses of ethion (5 mg/kg, 20 mg/kg, 60 mg/kg, 100 mg/kg, and 120 mg/kg) dissolved in groundnut oil were orally administered to female rats as a single dose. The animals were monitored for clinical signs for up to 14 days. Results: Female rats displayed typical signs of OP toxicity, such as exophthalmos, salivation, lacrimation, porphyria around the eyes and nose, nasal discharge, diarrhea, labored breathing, trembling, convulsions, and hyperextension of the hind limbs with bluish discoloration. Female rats exposed to higher doses of ethion succumbed within 3–4 h. No mortality was observed in the lowest dose group (5 mg/kg), although rats exhibited tremors and lacrimation. Postmortem examination revealed edematous and congested lungs in all rats. Ethion induced severe degenerative and necrotic changes in the liver and kidney, pulmonary edema, neuronal degeneration, hemorrhages, and edema in the heart. The results of the study revealed the oral LD 50 of ethion in adult female rats is 34.28 mg/kg body weight. Conclusion: Given that LD 50 determination is the initial phase in screening and evaluating the toxicity of a substance, this study could lay the groundwork for further investigations into ethion toxicity.