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Published in Spring 2003
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Mercury hot spots of North America
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Mercury (Hg) is a highly toxic liquid metal,
which most people recognize as the shiny liquid in fever thermometers. It occurs naturally in the environment, but it’s also generated through such human activities as the production of electricity from coal-fired power plants, waste incineration, fuel combustion and some industrial processes.
In its most dangerous form, methylmercury,
the health effects of its exposure to women of childbearing age and children can be devastating. For instance, in pregnant women methylmercury can accumulate in the fetal brain to cause brain damage. In adults, long-term exposure to the compound can damage the brain and central nervous system, causing loss of motor control, memory, hearing and vision.
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 There are 244 mercury hot spots in North America.
In Canada and Mexico, sites with high mercury concentration were selected as hot spots when the mercury concentration was greater
than 10ppb. In the United States, hot spots are indicated where mercury concentration was above US environmental standards for mercury.
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Because mercury is a naturally occurring and persistent substance, it can never be completely eliminated from the environment. Canada, Mexico and the United States are therefore working together to prevent and reduce mercury pollution due to human activities. On behalf of the three governments, the Commission for Environmental Cooperation (CEC) initiated a North American Regional Action Plan (NARAP) to achieve the “virtual elimination” of new sources of mercury.
Policy changes have already helped cut the generation of mercury pollution, which has doubled in the atmosphere since the beginning of the industrial age. The elimination of certain
mercury-based chemicals used in pulp and paper production in the 1970s led to a big drop in pollution. And in the 1980s, the elimination of most mercury in batteries and paints produced further
significant reductions.
Today, mercury “hot spots” still dot the North American landscape. This mercury hot spot map indicates 244 locations where the amount of mercury contamination exceeds the background, or
naturally occurring, level in the environment.
It’s the first time such a map has been presented
for North America based on national data.
<Download PDF version of the map>
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