Embedded lead shots in birds of prey: the hidden threat

In French wildlife rescue centers, veterinarians or volunteers often note embedded lead projectiles in X-rayed birds of prey that are not the cause of admission. To know if embedded lead in birds of prey may result in lead poisoning, 77 individuals admitted in three wildlife rescue centers in France were X-rayed and separated into two groups and then submitted to a blood lead level analysis. Blood lead levels of birds of prey with embedded lead projectiles are significantly higher (224.2 μg/L, 95% confidence interval 197.0–251.4 μg/L) than those without (142.9 μg/L, 95% confidence interval 124.1–161.7 μg/L). Among the birds of prey included in this study, the same difference was demonstrated in two species, the common buzzard and the common kestrel, when analyzed separately. Clinical lead poisoning was not observed but birds of prey with embedded lead have a mean blood level higher than the threshold of 200 μg/L defining the risk of subclinical effect occurrences and 60% of the lead-exposed birds had blood lead concentrations above the threshold. This result suggests that embedded lead projectile may release lead and induce some long-term detrimental effects.