By Daniel Weber, Ph.D.
This summer in Madison, Wisconsin, over 1200 scientists, industry representatives, and community activists from 58 countries delivered more than 1000 multidisciplinary papers at the 8th International Conference on Mercury as a Global Pollutant held (USA). During the 5-day conference, topics ranging from cycling of both natural and anthropogenic mercury to the biological effects of methylmercury, to treating mercury waste were discussed. Most significantly, it was the largest and most culturally diverse gathering ever held on the subject of mercury in the environment.
Unlike any of the previous 7 such conferences, this conference created a Conference Declaration on Mercury in the Environment. Once finalized, the document will summarize what scientists know and in what directions research efforts need to proceed to answer the most pressing questions about mercury toxicity. This Declaration will be published as a series of papers in the peer-reviewed, scientific journal Ambio. The goal of these articles is to provide a basis for policy makers to identify appropriate, scientifically sound actions to alleviate the global problem of mercury poisoning (they are not designed to advocate a particular policy direction).
Four major topics were addressed within the Conference Declaration: Source Attribution of Atmospheric Mercury Deposition, Health Risks and Toxic Effects of Methylmercury, Recovery of Mercury-Contaminated Fisheries, and Socioeconomic Consequences of Mercury Use and Pollution. For each topic, a panel comprised of internationally respected scientists was assembled to review all available data to create a review as to where the science is today.
Source Attribution of Atmospheric Mercury
Unlike the thousands of new compounds created every year that either mimic naturally occurring substances or are unlike anything ever created in nature, mercury is a natural element. The environmental concerns about mercury, therefore, relate not to its creation but to human activities that have greatly accelerated global cycling of mercury and, therefore, its availability to all forms of life (called “bioavailability”). Importantly, mercury, because it is a basic element, cannot biodegrade-it is mercury forever. Today, approximately 2/3 of the global background mercury is anthropogenic (from human sources), and 60% of all anthropogenic mercury emissions come from the use of coal to produce electricity. This translates into a tripling of the amount of mercury cycling in the environment compared to 150 years ago.
While it is fortunate that mercury emissions in Europe and North America are decreasing, it is, unfortunately, increasing elsewhere in the world, especially in countries such as China where there is a significant drive to industrialize. That fact, plus the propensity of mercury, especially the gaseous reactive form, to travel far distances in the atmosphere, means that local or regional controls will not be sufficient to reduce global environmental mercury burdens. A global response is required.