Cadmium and other elements in tissues from four ungulate species from the Mackenzie Mountain region of the Northwest Territories, Canada

• Cd and Hg levels differed between four sympatric ungulates in Canada’s Dehcho region.
• 15N and 13C signatures in ungulate muscle reflected diet and element accumulation.
• Renal histology showed few changes and no relationship with observed metal levels.
• 134Cs from the Fukushima accident was observed at low levels in two ungulate species.

Tissue samples from four ungulate species from the south Mackenzie Mountain region of the Northwest Territories (NT), Canada, were analysed for stable and radioactive elements and 15N and 13C stable isotopes. Elevated Cd concentrations in moose (Alces americanus) kidney have been observed in the region and are a health care concern for consumers of traditional foods. This study examined the factors associated with, and potential renal effects from, the accumulation of cadmium, and interactions with other elements in four sympatric ungulate species. Mean renal Cd concentration was highest in moose (48.3 mg/kg ww), followed by mountain caribou (Rangifer tarandus caribou) (13.9 mg/kg ww) and mountain goat (Oreamnos americanus) (5.78 mg/kg ww). No local sources of Cd were evident and the elevated levels in moose are considered to be natural in origin. Conversely, total Hg concentration was significantly higher in mountain caribou kidney (0.21 mg/kg ww) than in moose (0.011 mg/kg ww). 134Cs (t½=2.1 y) in mountain goat and Dall's sheep (Ovis dalli) muscle is evidence of deposition from the Fukushima reactor accident in 2011. 137Cs (t½=30.2 y) in all four ungulates is primarily a remnant of the nuclear weapons tests of the 1960s. The levels of both nuclides are low and the risk to the animals and people consuming them is negligible.Stable isotope δ15N and δ13C signatures in muscle showed a separation between the mountain caribou, with a lichen-dominated diet, and moose, which browse shrubs and forbs. Isotope signatures for mountain goat and Dall's sheep showed generalist feeding patterns. Differences in elemental and radionuclide levels between species were attributed to relative levels of metal accumulation in the different food items in the diets of the respective species. Kidneys from each species showed minor histological changes in the proximal tubule and glomerulus, although glomerular changes were rare and all changes were rare in mountain goat kidney. Kidney function was not expected to be affected in any species.Provisional Monthly Intake recommendations from the WHO indicate that Cd in moose organs will continue to be a public health care concern. However, traditional foods continue to be an important nutritional component of northern diets, particularly in consideration of the shift towards store-bought food.

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