What is 1080, and why do people oppose it?

Is 1080 saving the environment or destroying it?

The controversial poison is back in the spotlight after deer died following an air drop operation of 1080 targeting possums.

Up to 345 red deer are feared to have been killed after the drop at Molesworth Station in the South Island last October.

Outraged 1080 activists are using it as evidence as to why we need to rethink our use of the poison - but what exactly is 1080, and why do people oppose it?

What is 1080?

 1080 (sodium fluoroacetate) is the salt form of fluoroacetate, a naturally-occurring toxin found in several poisonous plants around the world.

Plants evolved this poison as a defence mechanism against mammals eating them. The salt form is more water soluble, and is mixed in with cereals to create a toxic bait product.

These bite-sized baits can easily be dispersed in New Zealand's forests - often by helicopter or plane, although it is also hand-loaded into bait stations.

Why do we use it?

New Zealand is the largest buyer of 1080 in the world, using over 80 percent of the production. The main reasons we use it are the cheap cost and ease of use.

Unlike other countries, New Zealand has no native land-dwelling mammals - while we have a large number of introduced mammal pests.

1080 can be used to kills all three of the big pests - stoats, rats, and possums. It also works against rabbits, ferrets and feral cats.

The Department of Conservation (DoC) says there are "no practical alternatives" and aerial 1080 is "the only method that can be deployed rapidly to managed a pest boom over vast or rugged terrain".

In 2011, a Parliamentary Commissioner for the Environment (PCE) investigation found that "not only should the use of 1080 continue (including in aerial operations) to protect our forests, but that we should use more of it".

Why do people oppose it?

Opposition to 1080 includes arguments over the poison's cruelty and its effects on non-targeted animal species. There are also claims it can taint water supplies, the food chain, and the local environment.

The death from 1080 has been described as "painful, torturous and slow" by SAFE, an animal rights group.

"From about four hours after poisoning until death all lethally dosed possums exhibited spasms involving the limbs or body," a witness to a possum poisoning told SAFE.

"Squeaking, gasping and gagging noises were also frequently heard during retching and terminal breathing."

1080 can also kill native reptiles, birds, fish and insects. Between 2008 and 2015, DOC recorded 24 kea deaths caused by 1080 from a population of 199 that were radio tagged.

Dogs can be particularly at risk of a prolonged and painful death, as they are known to scavenge the bait and the carcasses of animals that have died from eating the poison.

"Dogs are particularly sensitive to 1080 and must be kept away from baits and carcasses," DoC warns.

"Most dog deaths result from scavenging on poisoned possums, particularly the stomach."

Critics say there are other, more effective ways of controlling pests like possums, such as trapping. It's a view shared by some political leaders.

"I think we can develop a trapping industry in New Zealand to a greater extent than we have, I think there's the capacity of using hunters to gain the fur product," former Associate Health Minister Peter Dunne told Newshub following the PCE report.