Lead poisoning and its in vivo biomarkers in Mallard and Coot from two hunting activity areas in Poland

• Lead poisoning was diagnosed in 8% of birds hunted in southern Poland.
• Lead pellets were found in the gizzard content of 3% of birds.
• Pb content in feathers and excrements were not correlated with the internal one.
• Hb concentration and Ht level were not related to Pb blood concentrations.
• ALA-d activity was significantly correlated with Pb concentrations in blood.

In this study, we aimed to present the status of lead (Pb) poisoning in birds from southern Poland and the evaluation of in vivo biomarkers which may be used in the diagnosis without killing animals. This included the activity of δ-aminolevulinic acid dehydratase (ALA-d), hemoglobin (Hb) concentration, hematocrit (Ht) level and concentrations of Pb in blood, feathers and excrements. The significance of this work is the use of hunted birds which allow us to compare the signals of the chosen biomarkers with the internal response. Birds collected in the area of lower hunting activity (the Milicz ponds) revealed statistically lower Pb concentrations than birds from the Zator area. Pb poisoning was diagnosed in almost 8% of birds (including specimens from both areas), but lead pellets were found in 3%. The highest tissue concentration found was noted in kidneys of Mallard from the Zator area (36.55 μg g−1 d.w.). Significantly higher concentrations were noted in a few samples of gizzard content (up to 1047 μg g−1 d.w.) and excrements (up to 82.95 μg g−1 d.w.). Hb concentration, Ht level, concentrations in feathers and excrements seem not to be efficient biomarkers at noted Pb concentrations in internal tissues (brain, pectoral muscle, kidney, liver, spleen, bone). In contrast, we found a significant negative correlation between Pb concentration in blood and ALA-d activity which confirmed that this parameter can be used successfully as in vivo biomarker of lead poisoning also in low environmental pollution.