METALS IN MEDICINE AND THE ENVIRONMENT

What is Copper?

Copper is a valuable metal that has been used throughout history for many different purposes. Copper has been mined for over 2,000 years. Historical records show the Chinese recovered copper from blue vitrol by placing iron into the vitrol solution as early as 150 BC (1).  Copper is also a trace element that is needed to maintain many biological life forms and processes.

Mining

In order to meet societal demands for copper it has historically been mined from the ground. There are many different ways to procure copper from buried ore. The mining process begins with extraction of the ore from the ground. The ore then goes through smeltering and converting and the process ends with the refined ore being made into copper plates ready for sale to the world market (Figure 1) (2,3,4). This type of mining produces many harmful products such as sulfuric acid and sulfur dioxide along the way. Recent advances in the mining process that limit the volumes of harmful side products have been made. Mining methods incorporating liquid emulsion membranes and the use of microorganisms to remove copper from underground ore are currently being established as viable, economical ways to gather copper (5,6).

copper mining process

Figure 1.  The copper mining process: from the ground to cathode.

Environmental Effects

The way in which copper has been traditionally mined has resulted in the production of toxic waste products and negative changes to the immediate mine environment. The environmental consequences of the mining process are substantial and have both acute and chronic effects on the geography, water, vegetation and biological life in the surrounding areas. Environmental issues have been caused by mining in both ancient and modern times. Acid mine drainage (AMD, Figure 2, Ref’s 7,8) is caused when metal sulfides in the underground ore are exposed to the natural elements. The sulfides are oxidized and the products released are sulfuric acid and free heavy metals which contaminate the surrounding areas. AMD has had a huge negative impact on the environment, often resulting in the inability to sustain life in badly affected areas. The levels of copper and other heavy metals present in the ground and water around mines are significantly higher compared to similar geographical regions where mining has not occurred (7,8).

acid mine drainage

Figure 2.  Acid mine drainage.

Human Health and Copper Mining
The effect of copper exposure upon mine workers has been studied to a great extent.  The mechanisms by which the body incorporates copper are relatively well understood. There are two genetic disorders, Wilson’s Disease (WD) and Menkes Disease (MD) that result from mutations in enzymes that are involved in the transport of copper into cells of the body (Figure 3, Ref’s 9,10). WD results in chronic accumulation of copper in global body stores, which can be treated by chelation therapy. MD presents as a global shortage of copper in body stores, is not easily treatable and usually results in failure to thrive. Exposure to chronic high levels of copper can increase risk factors for lung cancer and coronary heart disease. Studies of copper mine workers both pre and post mortem have detailed the risk of chronic copper exposure and broken the risk up by parts of the copper mining processes (e.g. smeltering, converting, plating) (11,12,13,14).

human copper transport protein

Figure 3.  HCtr1: Human copper transport protein

References

(1) Dicinoski, W. A Revolution In Copper Recovery. Mining Magazine Page 258, May2000.

(2) Copper Processing.

(3) Copper Mining Info.

(4) Copper Extraction. www.wikipedia.org

(5) Rawlings, D.E., Dew, D., du Plessis, C. Biomineralization of Metal-Containing       Ores and Concentrates. TRENDS in Biotechnology 21, 38-44 (2003).

(6) Wright J.B., Nilsen, D.N., Hundley, G., Galvan, G.J. Field Test of Liquid   Emulsion Membrane Technique For Copper Recovery From Mine Solutions Minerals Engineering 8, 549-556 (1995).

(7) Wilson, B., Pyatt, F.B. Heavy Metal Dispersion, Persistence, and     Bioaccumulation Around An Ancient Copper Mine Situated In Anglesey, UK.       Ecotoxicology and Environmental Safety 66, 224-231 (2007).

(8) Kant, P.K., Sharma, R., Roy, M., Pandey, M. Toxic Mine Drainage From Asia’s    Biggest Copper Mine At Malanjkhand, India. Environ Geochem Health 29, 237-248 (2007).

(9) Cai, L., Li, X., Cherian, M.G. Essentiality, Toxicology And Chelation Therapy Of   Zinc And Copper. Current Medicinal Chemistry. 12: 2753-2763 (2005).

(10) Wang, T., Guo, Z. Copper In Medicine: Homeostasis, Chelation Therapy And Antitumor Drug Design. Current Medicinal Chemistry. 13: 525-537 (2006).

(11) Thomassen, Y., Nieboer, E., Romanova, N., Nikanov, A., Hetland, S.,       VanSpronsen, E.P., Odlnad, J.O., Chashchin, V.  Multi-component assessment of worker exposures in a copper refinery. Part 1. Environmental Monitoring. J. Environ.Monit. 6: 985-991 (2004).

(12) Adam, B., Aslan, S., Bedir, A., Alvur, M. The Interaction Between Copper and Coronary Risk Indicators. Jpn Heart J 42: 218-286 (2001).

(13) Rencher, A.C., Carter, M.W., McKee, D.W. A Retrospective Epidemiological Study Of Mortality At A Large Western Copper Smelter. J Occup Med 19: 754-758 (1977).

(14) Federspiel, C.F., Layne, J.T., Bruce, J. Lung Function Among Employees Of A Copper Mine Smelter: Lack Of Effect Of Chronic Sulfur Dioxide Exposure. J Occup Med 22: 438-444 (1980).

Author: Sara Dudgeon