1080 and water quality

New Zealand uses 1080 to control introduced pests. Decades of research show that 1080 degrades quickly in water and soil. There are also regulations that protect drinking water supplies.

There are hundreds of peer-reviewed papers examining the behaviour, properties and persistence of 1080 and its toxicity in creatures from frogs to ferrets to farmhands.

Dave Hansford, New Zealand Geographic

Solubility is an important factor

1080 – sodium fluoroacetate – is the salt form of a naturally occurring plant toxin. The salt form is used because it dissolves in water. Solubility (being able to dissolve in water) is important because:

• 1080 can easily be made into bait products
• after an animal eats the bait, the salt bond dissociates (separates), leaving the fluoroacetate in solution, and this begins a series of chemical reactions that kill the pest
• 1080 is readily dissolved by rain, stream water or groundwater and then dispersed (spread).

Laboratory tests can detect 1080 in water at very low concentrations. The standard measurement is in parts per billion (ppb) – 1 microgram (or 1 millionth of a gram) of 1080 per litre of water.

The fate of 1080 in water and soil

Due to its high solubility, 1080 easily leaches from baits that are exposed to rain or from baits that fall into waterways. 1080 becomes diluted in groundwater and surface water, and bacteria in the water break it down. National Institute of Water and Atmospheric Research (NIWA) scientists showed that, in flowing water, 1080 leached from submerged baits within 12 hours and was not detected in water samples collected within 24 hours (Suren & Lambert, 2006). Leaching and dilution rates do not depend on the temperature of the water (Wright, 2011).

Over a 30-year period (1990–2023), scientists tested over 2,000 water samples taken within 24 hours of aerial 1080 operations. Only 3% of the samples had traces of 1080, and the level averaged 0.2 ppb, excluding a sample that was incorrectly handled. They also tested 600 samples used for human or stock drinking water supplies. Only four of the samples had 1080 residues. At 0.1–0.2 ppb, these were well below Ministry of Health requirements (see below).

We use a very sensitive test, able to detect 1080 concentrations as small as 0.1 parts per billion. That’s the equivalent of finding a single gram of 1080 in one hundred 10-tonne trucks.

Dr Alastair Suren, freshwater ecologist

Manaaki Whenua – Landcare Research scientists looked at what happens to uneaten baits. The 1080 residues leach into the soil where they are broken down into non-toxic substances by soil bacteria and fungi. They found the 1080 concentration in soil is usually less than 0.1 ppm following a bait operation – too low to affect soil invertebrates like earthworms and microorganisms (O’Halloran et al., 2009). The leaf litter also had low concentrations of 1080 – 200–500 times lower than the amount required to kill a native insect such as a wētā (Wright, 2011).

Protecting drinking water

All aerial 1080 operations must have the approval of a medical officer of health or health protection officer who is also a warranted hazardous substance enforcement officer. Aerial 1080 pest control industry guidelines state that it is essential to check with the Public Health Unit of the local district health board where there may be a risk to public health from the proposed use of the 1080 and whether a permission is required.

An enforcement officer from the Public Health Unit will assess the application and place conditions on the operation to manage public health risks. For example, enforcement officers exclude areas from aerial drops to protect drinking water supplies (Hansford, 2016). In addition, regional councils may require bait-free buffer zones around larger streams (page 32).

Additional safety precautions are often taken before an aerial operation. Public water supplies may be temporarily disconnected. Water tanks in back-country huts are shut off until they can be tested.

Ministry of Health water and drinking-water standards

The Ministry of Health has set two measurements for the acceptable concentration of 1080 in water. The provisional maximum acceptable value (PMAV) is 3.5 ppb. At this concentration, the Ministry believes that someone can drink water for more than 70 years and not be exposed to a significant health risk. As an extra precaution, the Ministry has also set a drinking-water standard that is even smaller – 2 ppb.

At the rate of 2 ppb, the Ministry guidelines for drinking water note that:

• to receive a fatal dose, a 70 kg person would need to drink 70,000 litres of water in one sitting
• for sublethal effects to occur, a 70 kg person would need to drink 2,680 L of water containing 2 ppb of 1080 per day for an extended period of time.

References

Hansford, D. (2016). Protecting Paradise. Nelson, New Zealand: Potton & Burton.

O’Halloran, K., Jones, D., Booth, L. & Fisher, P. (2009). Ecotoxicity of sodium fluoroacetate (compound 1080) to soil organisms. Environmental Toxicology and Chemistry, 25(5), 1211–1218. https://doi.org/10.1897/04-424R.1

Suren, A.M. & Lambert, P. (2006). Do toxic baits containing sodium fluroacetate (1080) affect fish and invertebrate communities when they fall into streams? New Zealand Journal of Marine and Freshwater Research, 40(4), 531–546. DOI: 10.1080/00288330.2006.9517443

Wright, J. (2011). Evaluating the use of 1080: Predators, poisons and silent forests. Wellington, New Zealand: Parliamentary Commissioner for the Environment. Retrieved from https://www.pce.parliament.nz/media/1689/pce-1080-2017-web.pdf (now access via https://pce.parliament.nz/publications/evaluating-the-use-of-1080-predators-poisons-and-silent-forests)