Organic contaminants in Arctic Caribou

1. Contaminants in Canadian Arctic Caribou Mary Gamberg, Northern Contaminants Program Whitehorse, Yukon 150 ppm Porcupine Porcupine Dolphin and Union Bluenose East Dolphin and Union ppm Bathurst Bathurst Beverly Qamanirjuaq Qamanirjuaq George River George River Affaires indiennes Indian and Northern et du Nord Canada Affairs Canada • Objective • To determine levels of and temporal trends in contaminants in Arctic caribou • in order to: • Provide information to Northerners regarding contaminants in this traditional food, so that they may make informed choices about food consumption. • Provide information to wildlife managers regarding possible health effects of contaminants on Arctic caribou populations • Further understand the fate and effects of contaminant deposition and transport to the Canadian Arctic • Methods • We work with hunters to obtain samples from successful caribou hunts. They provide: • Whole kidneys – analyzed for metals • Liver – some analyzed for organic contaminants • Muscle – some analyzed for metals or organics • Teeth – used to age the caribou • Tissues are analyzed for contaminants by the National Laboratory for Environmental Testing (Environment Canada, Burlington). • Results are reported in a synopsis report prepared for the Northern Contaminants Program each spring and communicated to the communities using a variety of methods. GEOGRAPHICAL TRENDS MERCURY INTAKE BY PORCUPINE CARIBOU Renal cadmium concentrations in 4-6 year old caribou from the Canadian Arctic (mg/g dry weight) Female caribou tend to have higher concentrations of mercury than males. Caribou hunter, Horton Lake, NWT. Photo courtesy of Susan Kutz TEMPORAL TRENDS Mercury was measured in caribou forage from the Porcupine caribou calving grounds and the wintering area. A Canadian Wildlife Service forage intake model was adapted to estimate mercury (total and methyl) intake over a calendar year, by Porcupine caribou bulls, cows and cows with bulls (ie. non-pregnant cows that did not travel early to the calving grounds). There was no difference in mercury intake between cows that did or did not travel to the calving grounds. However, cows and bulls take in roughly the same total amount of mercury, since females need to eat more (due to their smaller body size and reproduction). Therefore they eat proportionally more mercury and have proportionally higher concentrations in their kidneys. Cadmium Renal cadmium in barren-ground caribou indicates a slight increase from east to west in the Canadian Arctic while renal mercury indicates the opposite geographical trend. Both trends likely reflect a combination of naturally occurring local metals as well as atmospheric deposition of cadmium and mercury from atmospheric long-range transport from North America, Europe and Asia. Overall, renal mercury in the Porcupine caribou has not increased or decreased over the past decade. It does appear to cycle, probably with local environmental factors such as temperature and precipitation. Care should be taken when attempting to infer a temporal trend from mercury tissue concentrations from a few widely separated years. CADMIUM AND MERCURY In general, organic contaminant levels are low in caribou (as in most of the terrestrial system). New, or ‘emerging’ contaminants predominate (i.e. PFCAs and PBDE 209) in organic contaminants in Arctic caribou. However overall levels are low, particularly in comparison with marine mammals. ORGANIC CONTAMINANTS Cadmium is a toxic metal of concern that has been found at high levels in some caribou herds in the Arctic. Cadmium accumulates in the kidneys and livers over time, so older animals have a higher body burden than younger animals. The major source of cadmium to the Arctic is the production of lead and zinc. Cadmium, as a by-product of this process, is released into the atmosphere and the long-range movement of air masses transports it to the Arctic. Mercury is a toxic metal of concern that has been found in caribou kidneys across the Arctic. Mercury occurs naturally as elemental mercury and as organic and inorganic compounds. Methyl mercury is more available to animals than inorganic mercury and can affect the nervous system, particularly of the growing foetus and the young. The primary source of mercury to the Arctic is the burning of fossil fuels, particularly coal, and waste incineration. Mercury Renal mercury (total) concentrations in fall-collected male caribou from the Canadian Arctic (mg/g dry weight) Organic contaminants in Arctic Caribou ACKNOWLEDGEMENTS Many thanks to the hunters and biologists who submitted samples to this program, and to the staff of Yukon Environment for their continuing support, particularly Philip Merchant and Angela Milani. Thanks to Derek Muir for much collaboration and Xiaowa Wang for technical assistance (NLET). Thanks to Don Russell for creating the mercury intake model for the Porcupine caribou and many helpful discussions. This project was funded by the Northern Contaminants Program and supported by the Yukon Conservation Society and Alpine Aviation Ltd. Fluorinated compounds such as PFOS are used in the production of fabric protectors, stain repellents and fire –fighting foams. PFOS and related chemicals that degrade to it have been banned in Canada and were withdrawn from commerce by the main manufacturer (3M) in 2001. The precursors of the PFCAs – fluorotelomer alcohols continue to be used and our expectation is that PFCAs will increase over time. A health advisory was issued from Yukon Health and Social Services in 1993 advising consumers to limit their consumption of kidneys and livers from some Yukon caribou. Cadmium does not accumulate to high levels in meat of caribou. NO HEALTH ADVISORY HAS BEEN ISSUED ON THE CONSUMPTION OF CARIBOU MEAT