A Review of the Levels and Distribution Patterns of Organochlorine Pesticides in the Eggs of Wild Birds in India

The presence of organochlorine pesticides (OCPs) in the eggs of avifauna is considered to be a significant tool for identifying the risk linked with the prevalence and persistent nature of OCPs. The eggs of wild birds represent an ideal selection for documenting the toxic effects of OCPs in natural ecosystems. Among the detected OCP residues, the frequency of detection was in the order of total hexachlorocyclohexanes (ΣHCHs) > total dichlorodiphenyltrichloroethanes (ΣDDTs)>cyclodienes (dieldrin and heptachlor epoxide (HCE)). The residues of DDT and its metabolites represented the major share (60%). Besides, p,p′-dichlorodiphenyldichloroethane (p,p′-DDE) residues exceeded the threshold levels of toxicity in the eggs of wild birds. Among the eggs of house sparrows (Passer domesticus) analysed for ΣOCP residues, 28% of the samples contained p,p′-DDE residues, which lead to their reproductive impairment. However, the magnitude of residue accumulation did not show any significant difference with respect to species and feeding habits. As a whole, around 5% of the egg samples contained p,p′-DDE and HCE exceeding its prescribed threshold level. These inferences hence uphold the inevitable need for systemic toxicity studies and real-time biomonitoring programmes towards the assessment of the harmful effects of toxic contaminants on the biotic components of our environment.