House sparrow biomarkers as lead pollution bioindicators. Evaluation of dose and exposition length on hematological and oxidative stress parameters

摘要

House sparrows (Passer domesticus) have been proposed as a key ecological indicator of urban pollution. Remarkably, we lack knowledge about the physiological effects of lead on this bird species. Therefore, this study was aimed to evaluate the effect of Pb on several physiological parameters in house sparrows exposed to environmental Pb concentrations. In a first experiment, birds were exposed to Pb sub-lethal doses (from 1.3 to 14.0 mu g of Pb/g animal/day) during 5 days, which resulted in a dose response increase of blood Pb levels and decrease of blood ALAD activity. However, at the higher doses tested ( 7 mu g of Pb/g animal/day) the blood ALAD activity inhibition (similar to 82%) remained constant. Hematocrit and hemoglobin were significantly reduced only at the highest-doses, and the stress indicator, heterophils to lymphocyte (H/L) ratio, did not show apparent changes.