（初めに右欄で英語を１つ選び、続いて選択肢から１つを選んでください。やり直すときは、英語を選び直すことから始めてください。右の［単語帳］を参考にすることもできます。）Mining, refining, and recycling of rare earths have serious environmental consequences if not properly managed. A particular hazard is mildly radioactive slurry tailings resulting from the common occurrence of thorium and uranium in rare earth element ores. Additionally, toxic acids* are required during the refining process.
Improper handling of these substances can result in extensive environmental damage. In May 2010, China announced a major, five-month crackdown on illegal mining in order to protect the environment and its resources. This campaign is expected to be concentrated in the South**, where mines are commonly small, rural, and illegal operations particularly prone to release toxic wastes into the general water supply. However, even the major operation in Baotou, in Inner Mongolia, where much of the world's rare earth supply is refined, has suffered major environmental damage.
The Bukit Merah mine in Malaysia has been the focus of a US$100 million cleanup which is proceeding in 2011. Residents blamed a rare earth refinery for birth defects and eight leukemia cases within five years in a community of 11,000 -- after many years with no leukemia cases. Seven of the leukemia victims died. After having accomplished the hilltop entombment of 11,000 truckloads of radioactively contaminated material, the project is expected to entail in summer, 2011, the removal of "more than 80,000 steel barrels of radioactive waste to the hilltop repository." One of Mitsubishi’s contractors for the cleanup is GeoSyntec, an Atlanta-based firm.