Behmke, S., P.Mazik and T. Katnzer. Submitted. Common samples used to diagnose lead poisioning are poor predictors of total body lead burden of birds. Journal of Wildlife Diseases.
Currently, the most minimally invasive technique by which to monitor lead in humans and wildlife is via blood collection. It is established that blood and other soft tissues (liver, kidney) are indicative of only recent exposure to lead and therefore, may not provide as comprehensive a view of lead exposure as do bone samples. However, if an individual’s blood (collected by phlebotomy) or muscle (collected by biopsy) lead levels could be statistically linked to the amount of lead found within its bone, it would permit use of less invasive sampling techniques to reveal total body burden of lead. To better understand the distribution of lead throughout the avian body, we analyzed lead concentrations from multiple tissues (femur, liver, kidney, breast muscle, thigh muscle) from 98 black vultures (Coragyps atratus) and 10 turkey vultures (Cathartes aura). Lead concentrations were many times higher in bone than in any other tissue. Although all soft tissues were poor predictors of bone lead levels, kidney lead concentrations most closely correlated to femur lead concentrations (r2 = 0.659). Discriminant function analysis also suggested kidney to be the soft tissue that best differentiated among “high” (≥ 30mg/kg), “medium” (< 30 but ≥ 20mg/kg) and “low” (< 20mg/kg) femur lead levels. The overall poor relationships between lead levels in soft tissues and in bone suggest that tissues commonly used to diagnose lead poisoning are unlikely to provide substantial insight into the long-term lead burden in birds. However, our research suggests that if bone samples are not available, kidney tissue is better than liver in predicting body lead burden and therefore should be the soft tissue collected to best understand an individual’s lead exposure history.