This project studies contaminant levels in Canadian Arctic caribou to determine if these populations remain healthy in terms of contaminant loads, whether these important resources remain safe and healthy food choices for northerners and to see if contaminant levels are changing over time.
Why is this important?
Cadmium and mercury levels in caribou kidneys and livers from across the circumpolar north, are higher than in domestic animals grown for food consumption.
A study by the Centre for Indigenous Peoples’ Nutrition and Environment recommended that a trend-monitoring program be established to verify that the levels are not rising from local or long-range inputs and that new contaminants be addressed as they arise.
What are we doing?
This project monitors two caribou herds, the Porcupine (YT) and the Qamanirjuaq (NU) every year. Monitoring herds from the eastern and western Arctic gives scientists a better understanding of the distribution of contaminants in the Arctic and the variability of contaminant burdens among herds. Two additional herds are monitored each year, depending on availability of samples and community concerns.
Twenty animals from each herd are sampled, and their kidneys analyzed for a suite of 34 elements, including arsenic, cadmium, lead and mercury. Livers are analyzed for a range of brominated and fluorinated compounds that have previously been found in caribou.
What do we know?
- Arctic caribou are largely free from contamination and are healthy to eat.
- Some caribou have high levels of mercury and cadmium in their organs. Some of the cadmium and mercury occurs naturally in the land, but some is brought here by wind from industry down south.
- Cadmium and mercury in caribou organs fluctuate over time.
- 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.
- In the spring, mercury may be lower in cows than in bulls, because some of the mercury is passed to the fetus and then to the calf through milk production.
- In the fall, mercury concentrations are higher in cows than in bulls, because cows are smaller and eat proportionally more food, therefore more mercury.
- Mushrooms may provide a pulse of mercury in the fall, because mushrooms can accumulate large amounts of mercury and are a preferred food when they are available.
- Mercury in the Arctic 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.
How our research is helping the world
More than two decades of contaminant data from the Porcupine caribou were part of the evidence that led the United Nations Environmental Program to create the Minimata Convention. This is a global agreement that will limit mercury emissions to the environment and ultimately reduce the mercury in Arctic caribou. The convention came into force on August 16, 2017, and as of March 22, 2018, 90 countries have ratified thereby agreeing to reduce their mercury emissions. We are making a difference!