Extracting valuable minerals and a Pandora’s Box of problems

A notorious pollutant used in gold extraction is mercury. In the vicinity of gold extraction sites, it may be found in high concentrations in fish, affecting local populations. Mercury also ends up in the atmosphere, from where it returns to forests. For example, 90% of fish caught by rural villagers south of gold mining areas of the Tapajós River in Brazil were found to be contaminated with methyl mercury². This chemical is dangerous for the nervous system as well as fetuses.
http://wwf.panda.org/what_we_do/where_we_work/amazon/problems/other_threats/amazon_mining/