Ahead of protests against the use of 1080 poison planned for this weekend, experts have again set out the hard science around the pest-busting tool. Toxicologist Dr Belinda Cridge (BC) and AgResearch chair in reproduction and genomics Professor Neil Gemmell (NG), both of Otago University, and Auckland University conservation biologist Associate Professor James Russell (JR) fielded these questions from the NZ Science Media Centre.
What are the persistent concerns people have about 1080?
BC: As I understand it, the ongoing concerns are around non-target species toxicity and water contamination.
Non-target species toxicity means that species that are not being targeted by the poison drop consume the poison and die.
Common concerns centre on deaths concerning other native species, such as birds and fish, and hunted species such as deer and pigs.
There is debate about how many of these deaths are directly caused by 1080 exposure as compared to other causes.
1080 is toxic to all species - as a toxicologist, actually everything is toxic if you are exposed to enough of it so 1080 isn't novel in this regard.
However, birds and reptiles seem to have a degree of tolerance.
In contrast, mammals are very susceptible to 1080 toxicity and so in New Zealand where all mammals, except sea lions and a bat species, are introduced, 1080 is an important pest control tool.
The other concerns are around 1080 leaching into waterways and causing a range of effects to wildlife and humans.
Scientifically, the understanding is that the original 1080 compound is broken down quickly in the environment and that 1080 doesn't persist in the environment or water like many other toxins.
This makes it unlikely that it will accumulate in waterways and cause down-stream poisonings.
Have there been any new developments in research into its effects over recent years?
BC: Scientific work has slowed down on 1080 as most recent research efforts are focused on finding alternatives.
Many people will be aware that New Zealand is fairly unique in its large-scale use of 1080, this is because we are in the privileged position of having few native mammals.
Therefore, we are uniquely placed to use 1080 in pest control.
Since 2014 only 400 articles on 1080 have been published worldwide in scientific journals, so around 100 per year.
Many of these are case studies of poisonings - 1080 is used in other countries, just not to the same scale - or studies that are referring to 1080 in comparison to other toxins.
We understand the mechanism of toxicity of 1080 fairly well and New Zealand scientists, in particular, have done a lot of work on the toxicity and environmental fate of this compound over many years.
Are there any areas of uncertainty that more research would be helpful to resolve?
BC: From my own interests, I would like to understand more about how 1080 is detoxified in the body as this may give us clues as to why dogs and kea and have a unique sensitivity to the compound.
But, this is because this is my area of expertise.
I think overall we actually have a very good handle on what the toxin does and at what doses.
Developments in targeted application using GPS have improved the overall safety of the compound as it is much less likely to be found in non-target areas.
These type of technological advances are much more important for the ongoing use of 1080 and to improve its overall use and safety.
With that said, I suspect the public will remain sceptical of 1080 due to its history of use in this country.
This creates many issues that are not able to be resolved by scientific evidence alone.
Toxin baits, like 1080, have played a major role in pest control in New Zealand - what other options are being investigated and how would these work?
JR: Pest control to achieve biodiversity outcomes requires removing pests from the ecosystem.
Traditionally, the tools fall into the three classes of traps, toxins and biocontrol, and can be either lethal or non-lethal.
Non-lethal tools are typically inefficient: They either can't scale up, are not cost-effective, or in some cases are even less humane than a quick death.
Scientists are always refining all three tools so they are more humane, more pest-specific, more efficient and more cost effective.
For example, new self-resetting traps have been developed, and sowing rates for 1080 have been reduced ten-fold.
When deciding what pest control tool to use managers must optimise efficiency - does it kill enough pests to restore biodiversity? - humaneness - does it do so humanely? - and cost.
Currently, aerially delivered 1080 is the optimal tool for mammalian predator pest control over most of New Zealand, costing $12-16 per hectare, being relatively humane, and achieving conservation goals.
Looking to the future, scientists such as those working in the Biological Heritage National Science Challenge are investigating all three types of tools.
They are developing new lures to make trapping more efficient, new toxins which are more humane and only harm the targeted pest species, and investigating the potential of genetic editing as a form of biocontrol.
They are also considering the bioethics of predator control, so that the social, cultural and ethical issues of pest control are incorporated into decision making.
Gene editing is one of the novel pest control tools with most potential, as it could be a non-lethal tool that allows pest populations to breed themselves humanely to extinction.
However, such a novel tool would require New Zealanders accepting gene editing, and is yet to be even developed, let alone proven as efficient and cost-effective.
What kind of timeframe might there be for new pest or predator control tools to be used in New Zealand?
JR: New Zealand scientists, engineers and innovators are always making incremental improvements in pest control tools to achieve better biodiversity outcomes through more efficient, humane and cost-effective tools.
These include modifying existing tools and inventing new variations of old tools.
This work is happening every day and government, private landowners and community groups are already using the improved tools across the country.
Entirely novel tools, particularly those in the area of biocontrol, require extensive laboratory development, testing and regulatory approval to demonstrate safety and efficacy before being trialled in the field.
Gene editing as a pest control tool is likely to be over a decade away from deployment in New Zealand, if it is even proven to be viable.
Our wildlife cannot wait until such new tools are developed and approved, and so until then, we must continue to use the most optimal tool we have, which is aerial 1080.
What genetic tools might be useful for future pest or predator control? What kind of timeframe might we expect for these to be in use?
NG: Pest control with current technologies over significant spatial scales is possible, but it's time-consuming and expensive.
The best tool we currently have for large-scale pest control is 1080.
It is aerially deployed, with precision, at the lowest amounts required to keep pest species in check so that our native birds and other species stand some chance of survival, and it rapidly breaks down in the environment.
The case of 1080 use is well established and it works – where it is used our native species are recovering, where it is not they die, it really is that simple.
While 1080 is the best tool we currently have in our ongoing battle with mammalian pests, we are constantly seeking improvements to our pest control toolkit.
As a nation, we are currently investigating approaches that are more humane, species-specific, and that provide persistent control across large areas without the ongoing cost of deployment.
Among this list of new tools, genetic control technologies are promising approaches that might help us meet that goal.
The most direct approaches currently being explored are species-specific toxins.
Essentially, we look for genetic or biochemical features unique to the species we wish to control so that we might identify toxins that will only work only on that species or its close relatives – think of it as a biochemical Achilles heel.
To date, there are promising "species-specific" toxins identified for stoats and rats.
However, it will likely take many years before such substances can be proven to be specific and approved for use in our environment.
If we are serious about Predator Free 2050 and wish genetic technologies to be part of the solution we need to step up the conversations, increase our investment, and start planning out what the workflow for this project would look like over the next decade plus.
If we start today we need months to plan, several years in the lab, and years for controlled field trials, before eventual deployment at landscape scales.
It will take massive effort and years to achieve eradication of possums, rats and stoats - recent models on some hypothetical, ideal, gene drives suggest 20 years from deployment to eradication.
This is the New Zealand version of the Space Race and we need commitment and resource aplenty if we are to achieve it.
It can be done, but whether we have the resolve to resource this appropriately and see this through to completion remains uncertain.