Lake Waikaremoana, East Coast
Image: Tahu Taylor-Koolen | DOC

1080, the environment and plants

Introduction

1080 is biodegradable, which means it breaks down naturally into basic, safe components that go back into the earth.

1080 is suitable for aerial predator control because uneaten baits containing 1080 will degrade into non-toxic elements that don’t harm the environment.

1080 can’t accumulate in the environment or remain in the food-chain like some other pesticides. This is because it’s easily diluted by water and detoxified naturally.

How does 1080 breakdown in the environment?

Step 1: The 1080 washes out of the bait

Any uneaten baits become soft from rain or dew. This allows the 1080 to leach out into leaf litter and soil where it is diluted further.

DOC wants target animals to eat the bait before the 1080 washes out. So we only apply bait pellets when no more than 10mm of rain is expected for at least two nights.  

This makes sure the 1080 toxin won’t leach out of bait pellets before predators can eat them.

If there’s a lot of rain, research shows 1080 dilutes rapidly to undetectable amounts in groundwater and streams. The amounts are so small they have no toxic effect on animals or water wildlife.

Step 2: Natural microbes breakdown the 1080

Tests in a range of New Zealand soils and leaf litter show microbes break down the remaining traces of diluted 1080.

Bacteria and fungi in soil make natural catalysts (enzymes) that detoxify 1080. These release compounds which the microbes use as a food source. Whether tested in the lab or in the bush, studies show soil bacteria can thrive when 1080 is present.

Once 1080 biodegrades, all that remains in the soil are natural compounds and minerals. These include glycolate, fluoride and carbon, at levels that are normally found in the environment.

How long does 1080 take to breakdown?

The time 1080 takes to biodegrade in soil depends on the weather. 

At temperatures around 10–20 °C, 1080 washed from the bait pellets is broken down by soil organisms within 1-2 weeks. This still occurs at temperatures as low as 5 °C, but more slowly. In cold, dry conditions, traces of 1080 might take a few months to completely biodegrade.

To be sure the 1080 we’ve dropped becomes safe, DOC calculates a caution period for every 1080 operation site.

We calculate caution periods by using climate records and studies of 1080’s breakdown in bait pellets and carcasses. We don't remove warning signs until we can expect there’s no remaining residue in bait pellets, living animals or carcasses.

Does 1080 affect plants?

1080 is a copy of a natural compound produced by plants to discourage browsing by animals. This means plants don’t readily take up 1080, and 1080 traces don’t build up inside them. Few individual plants will encounter 1080 after an operation.

Most recent operations have used 6-gram baits spread at 2 kg per hectare. This is around one bait for every 30 square metres. Each bait contains such a minuscule amount of 1080 that only 100th of a teaspoon of the 1080 (0.012mg) will end up spread over an area the size of a tennis court.  At this rate, only a tiny proportion of plants are exposed and if they do take up any 1080, it doesn’t harm the plant.

Plants break down 1080 into natural compounds and minerals normally found in the environment, like glycolate, fluoride and carbon. Research shows the maximum time 1080 residue stays in a plant is around 38 days. 

Many plant species worldwide naturally produce the toxic component of 1080, fluoroacetate. Whether produced by plants or made for 1080, the toxic effect is identical.

Can 1080 impact rongoā Māori?

Some people have had concerns about 1080 and rongoā Māori. Fortunately, studies show 1080 doesn’t damage the health-giving properties of plants or forests or make them unsafe.

Scientists tested culturally important plants to see if they would absorb 1080 from bait placed where they grow. The tests showed pikopiko didn’t take up 1080, karamuramu took minuscule amounts, and watercress took a small amount that had all gone within 10 days.

Puha was also found to contain fluoroacetate naturally, although at barely detectable levels.

The studies showed the plants remained safe for rongoā Māori.

For any 1080 in these plants to have a poisonous effect, a 70 kg person would need to eat 132 times their bodyweight, or 9,300 kgs of uncooked puha in a single sitting. For watercress that had taken up traces of 1080, a 70 kg person would need to eat 31 times their bodyweight, or 2,200 kgs in a single sitting to receive a harmful dose of 1080.

Learn more about caring for rongoā Māori plants from practitioner Rob McGowan on the DOC blog.

References

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