Highly toxic possum bait has been found illegally dumped by the side of four roads in Northland.
Police and health authorities in the region are asking anyone who discovers more of the discarded cyanide packets to contact them immediately.
Northland District Health Board says packets of cyanide were discarded on roadsides last month.
The first load of dumped bait containing 150 packets of poison was left on a roadside near Russell on 21 September. Just over a week later, the Northland District Health Board received reports of more packets dumped near Kawakawa.
Medical Officer of Health Clair Mills says coming into contact with even a small amount will cause headaches, dizziness and confusion. "But if you were to swallow it, or your dog eats the bait, they rapidly go into a coma, usually can have a cardiac arrest and other neurological symptoms."
Dr Mills says if anyone coming into contact with the bait must wash it off with water and contact police or a medical professional immediately.
The maximum penalty for dumping poison is one year in prison.