Metal blood levels and hematological characteristics in wood mice (Apodemus sylvaticus L.) along a metal pollution gradient.

The present study evaluated whether blood could be used as a nondestructive tool for monitoring metal exposure and related hematological effects in wood mice (Apodemus sylvaticus L.) living along a metal pollution gradient. Soil concentrations of arsenic, cadmium, copper, lead, silver, and zinc decreased with distance from the emission source. Blood levels of cadmium and lead differed significantly among sites, whereas those of the other metals did not. Blood levels of cadmium and lead correlated with soil concentrations of cadmium and lead, respectively. No such significant relationships were found for the other measured metals. Hematocrit levels decreased in wood mice from the most polluted site (45.96% +/- 0.53% [mean +/- standard error]) compared to the reference site (48.04% +/- 0.47%). A negative correlation between hematocrit and blood levels of cadmium and lead was found. Erythrocyte count, leukocyte count, hemoglobin concentration, mean corpuscular hemoglobin (average wt of hemoglobin in a red blood cell in pg), and lysozyme activity did not differ among study sites. Mean corpuscular volume (average volume of a red blood cell in microm3) and mean corpuscular hemoglobin concentration (average proportion of hemoglobin in a red blood cell as a %) differed among study sites but showed no relationship with metal exposure. We conclude that whole blood from mice can be used for nondestructive monitoring of the exposure to nonessential metals under natural conditions. The present results indicate that decreased hematocrit levels may be an early warning signal for a negative impact of metal exposure on the oxygen-transport capacity of blood in wood mice in their natural environment.