The Institute for Water Management in Minas Gerais (IGAM) found arsenic levels more than 10 times above the legal limit in one place along the Rio Doce after the dam burst on 5 November, leading to at least 13 deaths 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 at seven places on the Rio Doce, which stretches more than 500 miles from the mineral-rich state of Minas Gerais to Espirito Santo on the Atlantic coast.
The allowable limit for drinking water (please, note, *drinking* water) is 10 parts per billion.
Allowable limits are usually set somewhere between 1/10 and 1/100 of dangerous limits.
Arsenic is of course a poison. A decent dose will kill you right away. Yet with As the limits are set at what causes health problems if ingested over long periods of time. For there are parts of the world where it is naturally present in the drinking water supply. Thus the general “safe” level is set at what people might ingest if they use a water source for decades.
Momentary peaks of 10 times the current allowable limits are therefore something we’re not all that keen on but they’re not actually a significant danger to either human or animal health.
The UN (and, obviously, Greenpeace et al) bleating about “toxic heavy metals” are therefore simply bleating. As anyone paying attention would know. Because iron ore tailings are just dirt. You don’t want it in the river, certainly, but it’s not a disaster if it does happen.
There was a disaster here of course, when the damn burst and drowned those poor people. But environmentally this is trivia.