In Australia, officials urged the residents to evacuate to a remote cattle station after the arsenic scare. Residents were found to have high levels of arsenic in their blood.
The Northern Territory coroner has declared Mount Bundy Station, 130 kilometres (80 miles) south of Darwin, a restricted area and called for the 140 residents to be evacuated.
"The evacuation was a precautionary measure to ensure people's safety and limit any further people from being potentially exposed to the arsenic source," Darwin Police Commander Kym Davies said.
A 17-year-old boy from Mount Bundy Station died in May, and while no official cause of death has been identified, arsenic poisoning is thought to have contributed to the death.
Eight other long-term residents of the station have been found to have elevated levels of arsenic in their system, police said, adding that the cattle station would remain closed until the arsenic source was found.
"Prolonged exposure is usually needed to record elevated levels of arsenic," said Northern Territory Chief Health Officer Doctor Barbara Paterson.
"All of the eight people who have recorded elevated arsenic levels have received medical attention and will be offered follow-up attention."
Arsenic is naturally occurring and chronic exposure to the element is linked with cancers of the liver, kidney, bladders and skin, as well as heart disease.
Fatal arsenic poisoning is rare in Australia, with a Royal Darwin Hospital spokeswoman saying there were only two such deaths between 1964 and 2007.