What's your poison? The 1080 debate

Ten-eighty has been used for decades in New Zealand to control introduced pests; this year, however, will be a game-changer with the Department of Conservation using helicopters to drop 650 tonnes of bait treated with the deadly toxin over an extra 500,000 hectares of forest in the next few months.

It’s a massive step-up in DoC’s usual predator-control programme – part of a new $21 million, five-year plan to kill as many rats, possums and stoats as possible.

So why is DoC doing this? What effect does this poison have on the environment? And what risk does 1080 pose to people?

Why now?

DoC’s efforts this year are an attempt to counter the effect of a natural process called beech masting.

Beech trees make up much of the South Island’s native forests, and ‘masting’ is the clever way they beat the mice and rats that love to eat their seeds.

Rather than releasing a steady amount of seed each year that all gets eaten by a steady population of rodents, the trees wait several years, then conduct a coordinated surprise attack by simultaneously producing huge dumps of seed. Overwhelmed by the sudden surplus, the rodents are unable to eat all the seeds, and more slip through to germinate.

It’s a smart tactic with an unfortunate side-effect: in mast years this massive excess food supply allows rats to produce multiple extra broods. Given enough food, a single female rat can produce a litter of 10 every eight weeks, with her young starting to breed themselves within five to six weeks. So beech masts cause rat numbers to explode, and this plague then triggers a second plague in the stoats that feed on them.

Eventually, however, the food bonanza ends, and the stoats and starving rats turn their attention on native insects, lizards and birds – which by spring will have vulnerable chicks in the nest. It’s a feeding frenzy that in the past has seen birds wiped out from whole regions – and judging by the amount of beech flower being reported in the country’s forests 2014 is set to be an unusually large mast, bringing an extra 30-40 million rats. DoC says a huge 1080 attack is the only way to save our birds.

What is 1080 and how is it used?

Properly known as sodium fluoroacetate, 1080 occurs naturally in some plants, especially in Australia, where it’s thought to have evolved as a deterrent to browsing animals – which may explain why it is particularly deadly to mammals. It even occurs naturally at extremely low, harmless, levels in some teas.

The toxin works by blocking the energy cycle inside an animal’s cells. This makes it a very effective killer – death is usually caused by heart or nervous system failure, but essentially it prevents every organ from functioning.

The 1080 used in New Zealand is made in bulk by the Tull Chemical Company in Alabama in the US – the company is the world’s only supplier. In fact, New Zealand is the world’s largest buyer of the toxin, using about 80 per cent of global supply.

That’s because with so few native mammals – we have just two species of bat, plus coastal critters like seals – New Zealand is particularly suited to 1080 use: it can be dropped in precious conservation areas in the knowledge that virtually any mammal it kills is a noxious pest.

You couldn’t do that sort of thing in a place like Canada, for instance, where wild mammals like mountain lions, porcupines and bears would all be put at risk.

In New Zealand it is applied to cereal or carrot baits that are dyed bright green or blue and sometimes treated with scents to make them repellent to non-target animals such as deer and attractive to pests. The baits are usually dropped from helicopters, with warnings on all tracks leading to the area, and notifications posted online and in local media. Warnings are only removed once tests give the all-clear.

DoC is the main 1080 user in New Zealand, but it’s also used by the Animal Health Board to kill possums, which are known to spread the disease bovine TB to cattle.

A controversial killer

1080 has attracted controversy in New Zealand, with many people strongly opposed to its use.

Some of the loudest voices against it come from hunting groups like the Deerstalkers Association. 1080 will kill deer and pigs that eat baits, and pigs can also be killed from eating the carcasses of poisoned animals.

A 1080 drop can certainly reduce game animal numbers, although repellent treatments used recently are likely to have reduced this. However, regardless of whether the animals are killed, a 1080 operation puts game animals in the area off limits for human consumption for around six months, to the great frustration of hunters.

1080 can also kill the very birds that it’s used to protect. Birds from 32 different species, both native and introduced, have been found dead after 1080 drops. Most recently, five out of 39 endangered kea were killed by a single operation in 2013 – researchers speculated they had eaten the poisoned baits because they were used to feeding on unnatural foods after scavenging at ski-fields.

Perhaps the biggest issue with 1080 use in New Zealand is that dogs are extremely sensitive to it – about 20 times more sensitive than people, and 70 times more sensitive than rats, according to Australian government data.

Dogs that eat 1080 baits, or the bodies of poisoned possums, rats or mice, are very likely to die. Their symptoms can also be especially distressing for owners, as 1080 tends to attack the nervous system in dogs, causing uncontrolled running, fits and howling.

Can it harm people?

1080 is certainly deadly to humans – a 60kg person could be killed by 120mg of 1080. However in practice this is very unlikely and only one death has occurred in New Zealand – a possum hunter who died after eating 1080-laced jam in 1966.

And because possums, rats and stoats are so small and sensitive to 1080, the amount needed in poisoned baits generally isn’t enough to kill a person. According to DoC, a 15kg child would have to eat around two 12g cereal baits to receive a lethal dose, while an 80kg adult would need to eat eight to nine baits. Similarly, if a 50kg bucket were accidentally dropped into a 100m² farm pond an adult would have to drink more than 400 litres of the water at one time to die.

According to the independent Parliamentary Commissioner for the Environment (PCE), tests also show that 1080 doesn’t cause cancer or affect human hormones and doesn’t break down into dangerous substances – although like other known toxins long-term exposure to high doses could damage organs and could affect development of unborn children.

This year the New Zealand Federation of Freshwater Anglers has warned that eating trout or eels from targeted areas could pose a risk to people if those fish had eaten poisoned animals (trout are known to feed on mice) or carcasses. However scientists have dismissed this as very unlikely. Trials where eels were fed poisoned possums show that a person would need to eat five tonnes of eel meat in one day to risk dying. DoC has said there is little to no risk, but has agreed to run a monitoring programme. Meanwhile experts on 1080 at Landcare Research have pointed out that people gathering trout or eels could simply choose to follow the restrictions placed on hunters and avoid areas where 1080 has been used.

1080 in drinking water

One of the major concerns raised about 1080 is that it could contaminate human drinking water collected from dams or rivers in 1080-targeted areas. This is something that authorities take very seriously and water is routinely tested after drops. Between 1990 and 2010, for example, some 2442 water samples were taken, with 96.5 per cent showing no trace – and the toxin has never been detected in drinking water above the Ministry of Health limit of two parts per billion.

And while it might not sound reassuring to hear that there has only ever been a little bit of poison in water, to put this in context the average cup of tea has a harmless natural level of 1080 of about five parts per billion from the tea leaves.

In fact, 1080 is broken down very quickly in water and even damp soil – and doesn’t leave toxic residues or by-products. Poison from bait that fell into a stream, for example, would be quickly diluted to non-toxic levels, before being completely biodegraded within two to six days.

Why use it at all?

Despite its somewhat chilling ability to kill, 1080 is actually particularly suited to use in New Zealand, and most conservationists believe we are lucky to have it.

For a start, there is a very serious need for widespread predator control here. When the first Europeans arrived the country’s forests were a riot of noisy bird life. Yet today our remaining wooded areas are too often eerily silent.

Birds like kiwi are at risk of becoming extinct on the main islands within our lifetime; there are only 130 kakapo alive in the world today, and dozens of our native animals are in serious decline – and this is largely because New Zealand comes under attack each night from possums, rats and stoats which together chew through an astonishing 70,000 native birds and eggs every 24 hours.

Targeting an area with 1080, however, can wipe out these pests, allowing vulnerable chicks enough time to grow and leave the nest. And while it does kill some non-target species, including protected native animals, a definitive report on 1080 by the PCE in 2013 concluded that native birds are far better off when 1080 is used. For example even though kea are known to have been killed by it, they are also shown to have as many as four times as many chicks survive when the poison is used, meaning the benefits for the species as a whole far outweigh the negatives. And 1080 has never been recorded to have killed a kiwi.

Are there alternatives?

Trapping or shooting pests can often seem preferable to using poison. Yet in reality even the best multi-use traps need to be set and monitored by fit bushmen to be effective, and there simply aren’t enough experienced people – and there is far too much inaccessible, rugged land – for trapping or shooting to ever be a complete solution for pest control here.

By contrast 1080 can be dropped by helicopter into the most dangerous, remote areas for an instant (and relatively affordable) pest knockdown.

As for alternative poisons, the other options are either too dangerous for humans, too cruel, won’t kill stoats, or last too long in the environment compared to 1080, which biodegrades so quickly it can be used with no long-term risk.

Ultimately, this means there are currently no realistic alternatives for controlling pests, leaving us with the conclusion that, unless we’re prepared to see precious native animals like the kiwi and kakapo wiped out, 1080 poison is – for now – a very necessary tool.

Is 1080 cruel?

1080 generally kills within 24 hours and the official line from the National Animal Welfare Advisory Committee is that it’s a “moderately humane” way to kill pests; somewhere between cyanide (very humane – dead before you know it) and standard rat poisons (a long cruel death).

In short, it’s unlikely to be a pleasant way to go – but is seen as the least bad available option.

Sex and extinction – possum femme fatales

Cutting-edge research underway at Otago University could see the country’s possum problem solved without the need for poison, traps or guns.

Professor Neil Gemmell, director of the Centre for Reproduction and Genomics, believes it may be possible to breed a female possum that effectively sterilises the larger population.

He and a team are investigating whether it’s possible to select for a possum that only gives birth to other females or sterile males. Released into the wild, such an animal would pass on its genes until eventually there were no fertile males available, causing the population to collapse.

It’s an approach that would be completely cruelty-free, as no animals would be killed. And because Professor Gemmell’s team are using selective breeding techniques, rather than genetic modification, it’s unlikely to attract the controversy that has dogged 1080.

Currently the Dunedin researcher is testing the idea on fruit flies with help from a $1 million government grant, and hopes the technology could eventually be a silver bullet in dealing with all of our major introduced pests.

Resources

Read the Parliamentary Commissioner for the Environment’s report on 1080 by searching on the internet for ‘PCE 1080 report’.

Get maps and precise details of where pesticides have been used by searching ‘Pesticides summary DoC’.