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Dental Amalgam Fillings and the Environment

Mercury in the environment comes from natural (volcanic and geothermal activites) and human sources. However, since the advent of industry, mercury pollution coming from human sources have increased. Coal power plants, small-scale gold mining, and medical sources have been cited by the United Nations Environment Programme as a significant contributor to mercury levels in the environment. [1] (see figure 1 below)

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Source: US- Environment Protection Agency

This historical accumulation is evident in a recent study done on global oceans. The research team found that North Atlantic waters and most intermediate waters (between 100 and 1,000 meters) are €œanomalously enriched€ in mercury, compared to the deep waters of the South Atlantic, Southern, and Pacific oceans. Since industrialization, human disturbances have led to a 150 percent increase in the amount of mercury in intermediate waters .” [Lamborg et al, 2014] [2]

To trace the historical accumulation of mercury in the environment from anthropogenic sources, [3] Morowitz et al conducted an inventory of commercial sources from the 1850s to the present century. The research group concluded that decades of commercial mercury use have contributed to an additional 540 Gg of mercury to the environment€.[Morowitz, et al 2014] [4] (see Figure 2)

Figure 2.

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Source: Hardvard Publications

The researchers also reiterated that sources such as coal plants, small-scale gold mining, battery and chlor-alkali production have contributed significantly to mercury levels, thus upholding previous findings by the EPA and UNEP.

Mercury from dental amalgam fillings, the team also cite, is unique as it has pathways that affect land, air, and water. [5] Mercury from dental amalgam fillings may appear minimal but because of these different pathways, it is clear that mercury from the material can enter the environment as vapors released during cremation and incineration, as medical wastes in landfills or as water sludge, or as vapors released during application and removal. As a result, 50-70 metric tons of mercury from dental amalgam is released into the atmosphere, 35-45 metric tons is released into surface water, 20-25 metric tons is released into groundwater, and 75-100 metric tons is released into soil. [6]

The implication of high mercury levels in the environment cannot be fully understood unless there is a basic comprehension of mercury’s unique properties: mercury cannot be created nor destroyed. It is persistent, it is highly mobile, and it bioaccumulates in the food chain. If left unchecked and unaddressed, the steady increase of mercury levels in the environment will have serious implications on wildlife, the environment, and human health.

Reference:
[1] United Nations Environment Programme. 2002. Global Mercury Assessment. Geneva, Switzerland. Retrieved on 10 November 2014 at http://www.chem.unep.ch/mercury/Report/GMA-report-TOC.htm
[2] Lamborg, C.H., Hammerschmidt, C.R., Bowman, K. L., Swarr, G. J. m Munson, K. M., Ohnemus, D.C., Lam, P.J., Lars-Eric, H., Rijkenberg, M.J.A., & Saito, M.A. 2014. A Global Ocean Inventory of Anthropogenic Mercury Based on Water Column Measurements. Nature. Issue 512. Pp 65-68. Retrieved on 10 November 2014 at http://www.nature.com/nature/journal/v512/n7512/full/nature13563.html
[3] Fang, Janet, 06 August 2014. Mercury Levels in the Surface Ocean Have Tripled Since Industrial Revolution. IFLScience.com. Retrieved on 10 November 2014 at http://www.iflscience.com/environment/mercury-levels-surface-ocean-have-tripled-industrial-revolution
[4] Morowitz, H.M., Jacob, D.J., Amos, H.M., Streets, D.G., & Sunderland, E.M. 2014. Historical Mercury Releases from Commercial Products: Global Environment Implications. Environmental Science and Technology, Volume 48 Issue 17, Pp 10242-10250. Harvard University, Cambridge Massachusetts, USA. Retrieved on 10 November 2014 at http://acmg.seas.harvard.edu/publications/2014/Horowitz_2014_EST_HgProducts.pdf
[5] Ibid. p.7
[6] World Health Organization, 2011. Future Use of Materials for Dental Restoration. Geneva, Switzerland, Retrieved on 10 November 2014 at http://www.who.int/oral_health/publications/dental_material_2011.pdf