Caribou mercury levels




Contaminants such as heavy metals can persist in the environment and can have serious health implications for wildlife and for people—especially those who depend on traditional foods. In Canada, mercury is a risk to Canadian ecosystems and human health (Environment and Climate Change Canada 2016).

Many contaminants found in the North were never used in the region but have been transported here by wind and water, as they tend to settle in areas with colder climates. Many contaminant sources have been banned or restricted for many years, but still persist in northern ecosystems.

Caribou feed on lichen that can directly absorb airborne contaminants, such as mercury. The annual changes in mercury in Porcupine caribou may reflect changes in atmospheric mercury levels or changes in the environment (e.g., temperature, precipitation and wind) that affect how mercury moves from the air to caribou forage.


Arctic Caribou Contaminant Program. Please note that moose are no longer being sampled under this program.



What is happening?


In 2016, samples were collected from 23 Porcupine caribou.

Mercury concentrations in liver are generally lower than in kidneys, averaging 1.8 mg/g dry weight. While mercury fluctuates over time in caribou organs, over the long term it has remained stable in the Porcupine caribou herd.

Yukon Health advisories:

  • Meat (muscle) from Yukon caribou is a healthy food choice, as heavy metals are present in very low concentrations.
  • Intake of kidney and liver from Yukon caribou should be restricted depending on the herd (e.g., a maximum of 25 kidneys or 12 livers from the Porcupine herd per year).


Figure 1: Average mercury concentrations found in kidneys of the Porcupine caribou bulls



Taking action


The federal Northern Contaminants Program has measured mercury levels in the Porcupine caribou herd since 1994 to determine if these populations remain healthy (in terms of contaminant loads) and whether they remain a safe and healthy food choice for northerners.

The Porcupine caribou data were part of a dataset submitted by the Northern Contaminant Program to the United Nations Environmental Programme. The data was provided to support the Minamata Convention—a global treaty to protect human health and the environment from the adverse effects of mercury. Signatories to the convention work towards controlling how much mercury humans release into the environment. The 50-ratification milestone was reached on May 18, 2017. This means that the Convention came into force on August 16, 2017.

The AMAP Assessment 2015: Human Health in the Arctic has now been released. This assessment of Arctic human health impacts of contaminants and other stressors was conducted between 2012 and 2014 by an international group of over 60 experts. Recommendations from the report were delivered to Arctic Council Ministers at their meeting in Iqaluit in April 2015.


Caribou along Dempster Highway. Mary Gamberg.



Data quality

  • Data are available for kidneys and livers only. This does not reflect the amount of mercury in the muscle (meat) of the animal.
  • Mercury concentrations can be affected by the gender of the animal as well as season of collection.
  • Generally, this program collects samples in the fall.
  • Annual variation in mercury concentrations is common.



AMAP 2015. AMAP Assessment 2015: Human Health in the Arctic. AMAP, Oslo. 2015. Available from: http://www.amap.no/documents/doc/AMAP-Assessment-2015-Human-Health-in-the-Arctic/1346

Environment and Climate Change Canada. 2016. Canadian Mercury Science Assessment [modified 2016 Mar 8; cited 2016 Mar 29]. Available from: http://ec.gc.ca/mercure-mercury/default.asp?lang=En&n=A2D7E54F-1#BR-Sec2.

Gamberg, M. 2013. Arctic caribou contaminant monitoring program. Pages 257-266 in Aboriginal Affairs and Northern Development Canada. Synopsis of Research Conducted under the 2012-2013 Northern Contaminants Program. Aboriginal Affairs and Northern Development Canada. Gatineau, Quebec, Canada. Available from: http://publications.gc.ca/collections/collection_2014/aadnc-aandc/R71-64-2013-eng.pdf

Northern Contaminants Program. 2015. Northern Contaminants Program [modified 2016 Jan 25; cited 2016 Mar 3]. Available from: http://www.science.gc.ca/default.asp?lang=En&n=7A463DBA-1.

United Nations Environmental Programme (UNEP). 2015. Minamata Convention on Mercury [cited 2016 Mar 3]. Available from: http://www.mercuryconvention.org/.