According to the EPA's Toxics Release Inventory, gold mines are a leading source of toxic mercury air pollution in the U.S.
Mercury pollution: from gold ore to your table
Mercury is a naturally occurring element in some gold ore, which is primarily released into the air during the ore-heating stage of gold extraction.
Airborne mercury can travel great distances, ultimately settling in lakes and rivers. There, bacteria transform the mercury into methylmercury, which is toxic to humans. The mercury then accumulates in fish.
Predatory fish such as tuna and bass can have dangerous levels of mercury in their flesh, which upon ingestion will build up in humans as well. In 2008, 41 states had advised limiting fish consumption, issuing a total of 3,361 advisories due to mercury contamination. The advisories included over 16 million lakes and over 1.2 million river miles.
Mercury pollution’s toxic impacts on children
According to a 2005 study, between 317,000 and 637,000 children born each year in the United States are exposed in the womb to mercury levels above the Environmental Protection Agency's safety level.
Children of women exposed to relatively high levels of mercury during pregnancy show delayed onset of walking and talking, reduced neurological test scores, and delays and deficits in learning ability. The study further states that diminished intelligence of children exposed to mercury contamination before birth costs the U.S. economy $8.7 billion a year in lost productivity.
State and federal regulatory response
On March 8, 2006, the state of Nevada, home to 14 of the more than 20 gold mines in the U.S., adopted the first regulations requiring mercury pollution controls for gold mines, the Nevada Mercury Control Program. Subsequently, the EPA undertook wider discussions of emissions standards.
On December 16, 2010, the EPA put in place the first nation-wide mercury emission limits for gold and silver mines. The new rule is expected to reduce mercury emissions from 2,260 to 1,200 pounds per year, which is about a 77% reduction from 2007 levels.