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The 10 worst pollution problems in the world

Oct. 16, 2009, 11:21 p.m.
A woman mines for gold in Senegal.

Photo: iStockphoto

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Small-scale mining

At least a quarter of the world's gold comes from small-scale miners, like this woman in Senegal who is using toxic mercury to extract gold from its ore. When mercury and gold come into contact, the mercury absorbs the gold, creating a hard compound, but expelling mercury pollution.