Concentrations of Lead in Liver, Kidney, and Bone of Bald and Golden Eagles

Abstract.

The diagnosis of lead poisoning in eagles relies on autopsy information and residue analysis of lead in certain tissues, usually liver or blood. Similarly, the assessment of elevated lead exposure in eagles depends on the determination of lead concentrations in these tissues. Renal and bone lead concentrations have rarely been examined in eagles. We examined relationships among hepatic, renal, and bone lead concentrations in bald and golden eagles from the Canadian prairie provinces. Hepatic and renal lead concentrations were strongly related (R² = 0.87) while those in liver and bone were significantly but poorly related (R² = 0.22). Renal lead concentrations of 5 and 18 μg · g⁻¹ (dry weight) corresponded to hepatic lead concentrations of 6 and 30 μg · g⁻¹, the hepatic concentrations that we used as criterion levels associated with elevated lead exposure and death from lead poisoning, respectively. Lead was elevated in 19 of 119 and 21 of 109 liver and kidney samples, respectively. Of these 19 and 21 liver and kidney samples, 14 and 11, respectively, had lead concentrations compatible with death from lead poisoning. Taken together, lead concentrations were elevated in liver or kidney samples from 25 eagles and were compatible with death from lead poisoning in 15. Mean bone lead was higher in eagles with elevated hepatic lead than in those exhibiting background hepatic lead concentrations. However, even in the former group, bone lead concentrations were lower than those in lead-exposed individuals of other species of birds. Bone is probably not a useful tissue for identifying elevated lead exposure in eagles. Three of eleven birds that had been shot had anomalous renal lead concentrations, suggestive of contamination by residue from lead ammunition. It is important to exclude such birds when assessing lead exposure.