Age and proximity to local ore-smelters as determinants of tissue metal levels in beaver (Castor canadensis) of the sudbury (Ontario) area.

An examination of tissue metal levels in Sudbury-area beaver (Castor canadensis) revealed that animals in the vicinity of the local ore-smelters contained elevated burdens of Ni and Pb in the liver and kidneys. Tissue concentrations averaged 1.5- to 2.5-fold higher than background values and are believed to reflect accumulations resulting through food chain contamination. Tissue levels of Cu, Cd and Zn did not vary in relation to distance from source. Tissue Cd levels were uniformly elevated throughout the four populations examined and are believed to reflect an enhanced level of food chain transfer occurring on the poorly buffered, acid-sensitive soils of the area. Burden: body weight correlations indicated that tissue concentrations of Cd increased whereas Cu levels decreased as a function of animal age. Most striking among these age-related trends was the disproportionate uptake of Cd by renal tissues, resulting in 10-fold higher burdens than those present within the liver.