Emerging Problems with Mercury in Cambodia

Abstract

Background: Development of Cambodia is proceeding quickly with deforestation and hydroelectric dams potentially exacerbating mercury contamination from gold mines. Furthermore, mercury in consumer goods also threatens to compromise the health of Cambodians. Objectives: It is important to provide essential information on sources and pathways of mercury so that Cambodians can avoid exposure to elevated levels of mercury and to support informed decision making about management of consumer goods and the environment. Methods: We review current data available from our projects and the literature, compare the effects of similar development elsewhere, and discuss relevant methods to mitigate damage. Discussion: The mercury used by artisanal miners to extract gold contaminates thou- sands of miners. The extent of the toxic zone from gold mines is not clear due to the com- pounding effect of deforestation that is likely a larger source of mercury than the gold mines. Downstream from the gold mines, the levels of mercury in human hair in the Srepok River Basin are three to five times higher than that recommended by USEPA (1 μg g -1 ) and the level found associated with attention deficit hyperactivity disorder in the United States. In the same area, mercury in hair is at similar levels as has been correlated with suppressed male fertility in Hong Kong. Fishes in the Srepok River already show levels of mercury that exceed USEPA human consumption guidelines by 4-11 times. This problem could become worse with the completion of new hydroelectric dams, which typically in- creases levels of mercury in fish by fivefold. Unregulated Chinese traditional medicines sold in pharmacies exceed international guidelines by up to 30,000 times. Children's toys contain up to 2% mercury. Finally, there is widespread use of skin whitening creams with mercury that exceeds ASEAN guidelines by up to 35,000 times. Conclusion: Further field mercury monitoring of water, fish, and people is needed in Cambodia as the potential for toxicity is significant. Anticipated health problems are subtle and require professional analysis to detect. Those most at risk are women of child- bearing age and children. Assessment of mercury contamination must include several sources of mercury.