What is Mercury?

Mercury is a bioaccumulative, persistent, and neurotoxic heavy metal that threatens the health of humans and the ecosystem.

Mercury is present in the natural environment in small quantities; however, since the industrial age, humans have elevated the levels of mercury in the environment to several times their natural levels. Mercury is released when coal is burned to produce electricity, through the manufacturer, breakage, or by the disposal of mercury-containing products (such as mercury switches, thermometers, thermostats, and compact fluorescent light bulbs), as well as through industrial processes such as mining and chemical manufacturing.

Older mechanical thermostats can have 1-4 mercury switches, each containing approximately 2.5 grams of mercury. When mercury finds its way into bodies of water and wetlands it transforms into methylmercury – one of the most toxic forms of mercury – which then accumulates in fish. Fish contaminated with mercury are poisonous to the creatures that consume them. It takes only one gram of mercury (a little more than is found in a single car switch) to contaminate an eight-hectare lake to levels where the fish are unsafe for consumption.

Mercury & Your Health

Mercury exposure can be highly toxic to the nervous system and kidneys – producing symptoms such as anxiety and depression – and may also affect memory, thinking, and nerve function with possible tremors and reduced coordination. Pregnant women and women of childbearing years need to be especially careful since some studies have shown that when women have higher levels of methylmercury exposure from eating marine mammals, their children have been found to have lower intelligence scores, delayed verbal and motor skills, impaired hearing, and poor coordination.

Mercury pollution in Canada’s North has led to dangerously high levels of mercury in Canadian aboriginal peoples. The United Nations estimates that mercury toxicity has caused learning disabilities and impaired the nervous system of millions of children worldwide.

In an effort to mitigate the impacts of mercury pollution, mercury-laden fish consumption warnings are now issued for 90% of lakes in Ontario, Eastern Canada, the Northeastern United States, and the U.S. Midwest. Health Canada, the U.S. Food and Drug Agency, and other organizations have also recommended limiting intake of large, predator ocean-fish, particularly for children and women of childbearing years.