Sodium cyanide is acutely toxic to any living thing.
Incredibly small amounts of cyanide can kill fish. For example, cyanide measured at between 20-80 parts per billion can kill rainbow and brown trout. The same amount would be fatally toxic to humans. Sodium cyanide is one of at least three chemicals that would present significant risks to the environment from being transported to the site and as well, from being stored on-site. He reported that should NMC use cyanide at the highest estimated rate, it would need a truckload of cyanide approximately every 4-5 weeks.