Contaminants

People who eat caribou are concerned about the effects of this contamination, so there is a Canadian government-sponsored program to monitor these contaminants. The Porcupine (western Arctic) and Qamanirjuaq (eastern Arctic) caribou herds have been designated in the Northern Contaminants Program blueprint for annual monitoring of several contaminants including mercury, inorganic elements, PBDEs (polybrominated diphenyl ethers) and PFASs (per- and polyfluoroalkyl substances). The Porcupine caribou have been monitored for contaminants annually since the early 1990s and the Qamanirjuaq since 2006 so there is a good database for studying trends in contaminants in Arctic caribou over time. Other herds have been measured on occasion and give an idea of whether these contaminant loads vary according to location.

PBDEs are chemicals used in flame retardants and are common in the environment. Levels in the Porcupine caribou are very low and have not changed significantly from 2015 through 2017.

PFASs are man-made chemicals that are used in water repellents, stain guards and fire-fighting foams. Levels in caribou liver are low and some varieties of this chemical are declining over time in caribou, likely due to legislation banning their use. The Porcupine caribou did not show elevated levels of radioactivity due to the nuclear accident at Fukushima, Japan in 2011.

Caribou have mercury and cadmium in their kidneys and livers. Some of this is from naturally occurring mercury and cadmium and some is brought north by wind from industry down south.

Caribou muscle (meat), marrow and brain have very low levels of contaminants. Cadmium and mercury in caribou organs fluctuate over time but over the long term are remaining stable.

Mercury is generally higher in the spring than the fall, because the caribou eat lichens through the winter which are higher in mercury than their summer foods of grasses and flowering plants. Mushrooms may provide a pulse of mercury in the fall, because some mushrooms can accumulate large amounts of mercury and are a preferred food when they are available. Seaweed does not provide a significant amount of mercury to the Qamanirjuaq caribou. Mercury concentrations are higher in caribou cows than in bulls, because cows are smaller and eat proportionally more food, therefore more mercury. In the spring, mercury may be lower in cows than in bulls, because some of the mercury is lost to the fetus and through milk production. Mercury in caribou may be affected by rain, snow, wind, temperature, migration patterns, time of green-up and forage quality as well as mercury emissions coming from industry, forest fires and volcanoes.

Overall, contaminant levels in caribou are low and caribou meat remains a healthy and nutritious food choice.