RIO DE JANEIRO, (Reuters) – Illegal levels of arsenic and mercury polluted the Rio Doce river in the days after a dam burst at an iron ore mine in early November in Brazil’s worst-ever environmental disaster, according to tests by a state water agency.
The Institute for Water Management in Minas Gerais (IGAM), found arsenic levels more than ten times above the legal limit in one place along the Rio Doce after the dam burst on Nov. 5, killing at least 13 people and flooding thick mud across two states. Mercury slightly above the permitted level was also found in one area.
In total, IGAM found unacceptable levels of arsenic on one or more days between Nov. 7 and Nov. 12 at seven places on the Rio Doce, which stretches over 800 km (500 miles) from the mineral-rich state of Minas Gerais to Espirito Santo on the Atlantic coast.
The report, dated Nov. 17 but only released on IGAM’s website on Tuesday after pressure from prosecutors, appears to contradict claims by the companies responsible for the mine.
Samarco, the mine operator, and its co-owners, BHP Billiton PLC and Vale SA, have repeatedly said the water and mineral waste unleashed by the dam burst are not toxic.