Article

Carbofuran and its Toxic Metabolites Provide Forensic Evidence for Furadan Exposure in Vultures (Gyps africanus) in Kenya

Department of Chemistry, Maseno University, P.O. Box 333, 40105 Maseno, Kenya.
Bulletin of Environmental Contamination and Toxicology (Impact Factor: 1.26). 04/2010; 84(5):536-44. DOI: 10.1007/s00128-010-9956-5
Source: PubMed

ABSTRACT

Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl - 0.07 (carbofuran), bdl - 0.499 (3-ketocarbofuran) and 0.013-0.147 (3-hydroxycarbofuran) in beaks, bdl-0.65 (carbofuran), 0.024-0.190 (3-ketocarbofuran) and 0.017-0.098 (3-hydroxycarbofuran) in feet, 0.179-0.219 (3-ketocarbofuran) and 0.081-0.093 (3-hydroxycarbofuran) in crop content, 0.078-0.082 (3-ketocarbofuran) and 0.091-0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006-0.014 (carbofuran), 0.590-1.010 (3-ketocarbofuran) and 0.095-0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran.

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    • "Similarly, eastern Screechowls Megascops asio were exposed to baits laced with CM carbofuran (2,3 - dihydro-2,2-dimethyl-7- benzofuranyl methylcarbamate) and residues were detected in their talons after these had been weathered for 28 days post-exposure (Vyas et al. 2005). Residues of carbofuran and two of its primary metabolites (3- ketocarbofuran and 3- hydroxycarbofuran) were also identified in the highly weathered talons and beak of an African Whitebacked Vulture Gyps africanus recovered from an agricultural field in Kenya (Otieno et al. 2010, Otieno et al. 2012). We have also detected CMs (e.g., aldicarb) and OPs (e.g., chlorfenvinphos) in beaks and talons taken from the degraded carcasses of birds submitted to the Center for Analysis and Diagnosis of Wildlife (CAD) in Málaga, southern Spain, during routine wildlife forensic investigations (Richards et al. in prep). "
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    ABSTRACT: In many regions of the world, organophosphorus (OP) and carbamate (CM) pesticides are used to poison wildlife thought to be competing with human activities (e.g. hunting). Vultures may be secondarily poisoned or directly targeted, e.g. for muti or traditional medicine. Some OPs and CMs are so acutely toxic that animals will die with poisoned material still in their mouths - un-swallowed, before traces may have spread to other parts of the body. Even when death is more prolonged, the tissues in which residues have accumulated may deteriorate before the carcass is discovered, minimizing the chances of recovering viable samples for toxicological analyses that would conclusively identify poisoning as the cause of death. With all these factors in mind, we investigated the feasibility of detecting OP and CM pesticides in the oral cavity, with emphasis on the tongue and palate. A total of 60 degraded carcasses (n = 28 avian and 32 mammalian) recovered from various scenes of wildlife crime in Andalucía, southern Spain, where poisoning was suspected, were submitted to the Center for Analysis and Diagnosis of Wildlife in Málaga for necropsy and toxicological analyses. Of these, 20 and 24 avian and mammalian tongues, respectively, could be recovered for analysis. Separately, the palate from one degraded Cinereous Vulture Aegypius monachus carcass was also opportunistically retrieved and analyzed following an incident of vulture mass-mortality in which nine Griffon Vultures Gyps fulvus also perished. Residues or presence of OPs and CMs were detected in one avian tongue (analyzed with food from the mouth) and four mammalian tongues. Our findings suggest avian tongues alone are not optimal, but canid tongues and those of larger mammals may lend themselves well to analysis. Detection of the OP chlorfenvinphos (3.39 mg/kg) in the Cinereous Vulture palate (the only part of the carcass in which residues were detected) indicates this is a promising sample. To our knowledge, this represents the first time that OP and CM pesticides have been detected in tongue and palate samples. We recommend further exploration of oral cavity samples, especially within the context of the risk that residues therein may pose to human health.See supplementary file attached
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    • "Furthermore, carbofuran is known to be more persistent than other carbamate or organophosphate insecticides and thus often detected in water (Salman and Hameed, 2010). Low concentrations of carbofuran and its metabolites have been recorded in water samples from Kenya (0.005e0.495 mg L À1 ) in the farmlands (Otieno et al., 2010) whereas highest concentrations reported from Bangladesh paddy land water were 0.198 mg L À1 (Chowdhury et al., 2012). The World Health Organization specified the permissible limit of 0.007 mg L À1 for carbofuran (Stewart et al., 2002) in drinking water. "
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    • "Toxicological analysis is necessary for the confirmation of substances such as aldicarb and carbofuran and their metabolites because of their similar gross appearance and necropsy findings. High performance liquid chromatography with diode-array detector (HPLC-DAD) has been applied for the purpose of identification of different metabolites (Harper et al., 1998; Otieno et al., 2010). For example, the metabolites aldicarb sulphone (ASN) and aldicarb sulphoxide (ASX) have higher anticholinesterase action than aldicarb; ASX is 23 times more effective than aldicarb and 60 times more effective than ASN (Montesissa et al., 1994). "
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