The UN Environment Program report tallied 40 significant mine waste accidents in the past decade. Most involved dams or other storage areas that failed, releasing torrents of polluted water.
Among the accidents highlighted by the agency were a 2015 dam collapse at a Brazilian iron-ore mine that killed 19 people and the Gold King Mine disaster in the U.S. that spilled pollution into rivers in three Western states.
Although the rate of such accidents has been falling, the report warned that the consequences have grown more serious as waste impoundments get larger. The iron-ore mine accident in Samarco, Brazil, for example, released some 40 million cubic meters (52 million cubic yards) of waste that polluted hundreds of miles of rivers and streams.
The UNEP recommended governments and mining companies adopt a “zero-failure” goal for mining impoundments known as tailings dams and impose stronger regulations.
There are an estimated 30,000 industrial mines worldwide and hundreds of thousands of abandoned mines that continue spewing pollution for decades after they’ve closed.
Advocacy groups said in response to this week’s UNEP report that 341 people have been killed by mine waste accidents since 2008.
Waste storage sites are “like ticking time bombs,” said Payal Sampat with the U.S.-based group Earthworks, adding that governments and the mining industry have done too little to prevent accidents.
The International Council on Mining and Metals last year issued new safety guidelines that said catastrophic mine waste impoundment failures were unacceptable. The group called on companies to use construction methods and operating practices that minimize the chances of accidents.
The 2015 Gold King accident in southern Colorado occurred at an inactive mine where polluted water had been accumulating for years before a U.S. Environmental Protection Agency crew accidentally released it during cleanup work.
Luke Popovich with the National Mining Association in Washington, D.C., said the UNEP recommendations don’t apply to Gold King because it was caused by a government agency and not a mining company.
The EPA last year proposed new rules that would require companies to show they have the financial wherewithal to clean up pollution from shuttered mines. New EPA Administrator Scott Pruitt put the proposal on hold after President Donald Trump took office.