A comparison of heavy metal levels in the kidneys of High Arctic and mainland caribou populations in the Northwest Territories of Canada

Abstract

Aluminum, nickel, cadmium, mercury and lead levels were measured in the kidney tissue of Banks Island Peary caribou and barren-ground caribou, from the Bluenose herd, of the western Northwest Territories of Canada. Cadmium concentrations of Bluenose caribou were similar to those reported elsewhere for barren-ground caribou and showed a positive correlation with age. Cadmium concentrations of Peary caribou were significantly lower than those of Bluenose caribou regardless of age, were the lowest reported for caribou during winter, and did not show a positive correlation with age. Mercury levels, expressed on a wet weight basis, were similar to those reported for other barren-ground caribou. Mercury levels were significantly higher in Bluenose [mean 10.45 μg g −1 (dry wt.); S.E.=0.85; n=20] than Peary [mean 5.43 μg·g −1 (dry wt.); S.E.=0.31; n=20] caribou. Aluminum concentrations for Bluenose and Peary caribou were similar [mean 1.48 μg g −1 (dry wt.); S.E.=0.17; n=20 and mean 1.56 μg g −1 (dry wt.); S.E.=0.15; n=20, respectively), but were considerably lower than those reported for barren-ground caribou elsewhere. Lead and nickel concentrations were low and similar between Bluenose, Peary and other reported barren-ground caribou populations. Higher cadmium and mercury concentrations in Bluenose caribou are consistent with the hypothesis that caribou with a high dietary lichen component have higher contaminant levels. It is unlikely that subsistence harvesters would consume enough kidney during a year to exceed the tolerable intake of cadmium recommended by the WHO.