The Peruvian Ministry of Energy and Mining asked Congress to declare sodium cyanide a “controlled chemical input”. Currently, it is marketed and transported without restrictions — and last month killed five people. “Around 30,000 tons of granulated cyanide used by mining companies are freely transported on the highways,” says Alvaro Mejía, head of the mining ministry.

On Mar. 27, a truck carrying 20 tons of cyanide crashed into a bus 176 km north of Lima. Some of the material was dispersed, and in contact with the humid ground produced a toxic gas that killed five people and seriously affected 14 others.

Ian Moscoso, a United Nations expert, said cyanide gas can kill a person within a few minutes and cause severe damage to the nervous system, lungs and glands.

Cyanide “also affects all ecosystems reached by the toxic gases or contaminated liquids,” said Moscoso.