Assessing environmental contamination around obsolete pesticide stockpiles in West Africa: using the Nile monitor (Varanus niloticus) as a sentinel species

Abstract

Environmental contamination caused by obsolete pesticide stocks was assessed using the Nile monitor (Varanus niloticus) as a sentinel species. Organochlorines and organophosphates were quantified by gas chromatography in abdominal fat and the liver, respectively. Results were compared to those obtained from three other sites, characterized by different histories of contamination. None of the previously stocked pesticides were recovered. Low to moderate levels of 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE) were quantified in monitors from all sites. Malathion and 4,4'-dichlorodiphenyldichloroethane (4,4'-DDD) also were detected sporadically. Interindividual variability was substantial. Correlations between pesticide loads and individual characteristics were considered. The nondetection of previously stocked pesticides in the monitors' tissues, their contamination by other pesticides, and the value of V. niloticus as a monitoring tool for environmental contamination are discussed. The results indicate a situation of low concern and draw attention to the importance of local conditions in determining environmental dangers associated with potential pollution sources.