A 47-year-old man has been taken to hospital following an incident at a rural property in Central Otago involving cyanide.
Police said they were alerted to the incident in the Bannockburn area, near Cromwell about 6.15am.
"As a result of the information, police had concerns for a male resident's wellbeing in that area,'' Senior Sergeant Dave Scott said.
"The area was cordoned off and the male was located at about 8 o'clock this morning.
Ambulance officer and the Fire Service also attended.
"It involved decontamination of the scene due to the presence of cyanide," Mr Scott said.
The man was being taken to Dunstan Hospital for further assessment.
It is understood he was licensed to use cyanide in his work, Mr Scott said.
His condition is not life-threatening.
The Dunedin Fire Service hazardous chemicals unit would perform a full decontamination of the address this morning.