Investigation of single and combined effects of repeated oral cadmium and lead administration in ewes

Abstract

Cadmium is considered one of the most toxic elements in the environment, with its ubiquity, a multi-organs damage and long elimination half-life. This heavy metal can pose serious health problems and lead to various biological disorders. Our research investigated the adverse health effects related to subchronic oral exposure at regular low- dose treatment in Ouled Djellal non- lactating ewes. The study aimed to ascertain whether the subchronic co-exposure to Cd and Pb in Ouled Djellal non- lactating ewes exacerbates the toxic effects and what are the most sensitive indicator parameters related to the blood Cd concentration. Haematological and biochemical modifications as well as the interaction with Zn and Cu were investigated. The study was conducted during two periods: in the first one, which lasted four weeks, the ewes were not contaminated: animals during this period acted as a control group and all values obtained during this period are considered as control values. Two groups of five animals were used: the Cd group received cadmium chloride orally at a dose of 2 mg/kg/day and the Cd+Pb group received cadmium chloride orally at a dose of 2mg/kg/day in addition to lead nitrate at a dose of 2.5 mg/kg/day during 9 weeks. Mean blood Cd has increased after the cadmium administration in both Cd group and Cd+Pb group. The evolution of Cd levels in the blood over time is slightly different for the Cd+Pb group. ANOVA showed a time effect (P˂0.001). The effects of treatment and animals effect were not significant (P>0.05). Disturbance in haematological and biochemical parameters was observed. The balance of the essential elements was altered; resulting in a significant decrease mainly in Cu plasma concentrations. Student's t-test indicates that toxic effects were similar for the two groups. This multi-indicator approach based on changes in different sensitive parameters can is be pertinent for risk assessment.