Toxins Rob More Than A Decade Of Life From Millions

"For every gramme of gold, two grammes of mercury gets into the environment," Robinson told IPS. 
Like lead, mercury is an element, so it doesn't break down. Once released into the environment, it is there forever. High gold prices, driven in part by growing demand for jewellery, tempts the poor in Africa, South America and Asia to use mercury as a cheap and effective method of extracting gold from mined soil and rocks. 
http://ipsnews.net/news.asp?idnews=105833

The Hidden Costs Of Gold: Mercury Poisoning Blights Mining Communities

Used as a cheap and fast method of extracting gold, the mercury 
attaches itself to the metal, making it easier to separate it from 
rocks and other material. Fast, simple, and intuitive, it’s a popular 
and relatively cheap method for miners with little capital.

Most of it is then released into the environment, with 70 per cent of it 
usually finding its way into water systems, posing long-term risks for 
mine workers and communities who live downstream or downwind from
 areas being mined.



'Gold mining communities are especially vulnerable' says Carolyn
 Vickers of the World Health Organisation. 'It gets into the food
 chain, into the fish women eat and then passes into the baby in the
 womb, which impacts the development of their brains and affects their 
ability to think.'
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http://www.theecologist.org/News/news_analysis/1122019/the_hidden_costs_of_gold_mercury_poisoning_blights_mining_communities.html