Peru's President Ollanta Humala has declared a 60-day state of emergency in a large remote area of the Amazon jungle because of extremely high levels of mercury poisoning from illegal gold mining.
The country's environment minister said 41 percent of the population of Madre de Dios is being exposed. The mercury is not only in people, but also polluting rivers and fish.
The government plans to send hospital ships and loads of untainted fish to the area, near the border with Brazil.
Peruvian officials blame the mercury contamination on illegal gold mining, saying the miners use mercury to separate the gold from rock and dump the chemical into the rivers.
The government is trying to clamp down on illegal mining.