This case study illustrates the impacts of a long-standing scientific disagreement between federal departments on heavy metals, particularly mercury, and the efforts that have been made to resolve the issue.
Mercury occurs naturally in the environment and is also released as the result of human activities.
In certain forms it can be toxic to both humans and wildlife and can cause neurological damage. Despite long-standing regulations under the Canadian Environmental Protection Act and the Fisheries Act to curb emissions from specific sectors, mercury deposition continues to be a problem in many ecosystems. For example, five Canadian provinces and 39 American states have issued consumption advisories for freshwater sport fish because of mercury contamination. Common loons breeding in the Maritimes have the highest blood mercury levels in North America, which is affecting their ability to nest and raise their young. Scientists do not dispute mercury's impacts, but there is disagreement about the relative contribution of natural versus human-made releases present in the environment.