Dose- and Dosage-Dependent Spectrum of Respiratory Toxicity of Cypermethrin in Rabbits

Pyrethroids are popular insecticides. Shortness of breath and dyspnea are key signs of exposure; however, their respiratory effects are rarely studied. This study investigated the combination and ratios of specific blood tests and lung lesions as respiratory effects of cypermethrin (CY) in rabbits. The effects of CY at various doses and times are the novelty of this study. Doses (50, 100, and 150 mg.kg-1 body weight) of CY were injected intraperitoneally every week for up to 9 weeks in rabbits assigned into four equal groups. Data analysis revealed various respiratory signs, significantly (p ≤ 0.05) lower fibrinogen, higher neutrophils-lymphocytes (NL), LDH-lymphocytes (LL), and De-Ritis ratios (DR), and lesions in the lungs. The frequency and incidence of these effects were dose and dosage dependent. The CY leads to pulmonary signs and allergic effects. Lung injury increases cell-free heme in plasma, causing pulmonary edema with hemolysis. Emphysema and fibrosis followed the migration of basophils and mononuclear cells to the lungs. This study inferred that CY exposure caused lower fibrinogen, higher NL, LL, and DR ratios, and pulmonary lesions, which forecast poor immunity, especially increased risk for cardiac and lung diseases.