New Research Shows 1080 Highly Unlikely to Contaminate Water

A short HD video explaining new research shows that the vital possum control poison 1080 has no negative effects on either surface or ground water.

The independent research – conducted by NIWA on behalf the Animal Health Board (AHB) – examines what happens to sodium fluoroacetate (also known as 1080) when it leaches from uneaten cereal baits.

Results showed that over 99 per cent of the toxin-laden rainwater goes straight into the soil, where it is quickly broken down into harmless metabolites by soil micro-organisms, rather than flowing overland into streams. They also showed that the level of 1080 in soil water from scattered, individual baits within a catchment during normal possum control operations never exceeded one-third of the Ministry of Health drinking water standard, and may not even be detectable.

The study concluded that the effects of 1080 leaching from baits into soil water and stream water are extremely unlikely to have any adverse effects on water quality.

• Watch NIWA scientist Alastair Suren discussing the methodology results of the study here (HD video, 8 mins)

Background to the study

Freshwater ecologist Dr Alastair Suren led a series of field trials in rugged West Coast terrain where aerially-applied 1080 is considered critical to controlling possums. To maximize the chances of detecting 1080 in soil water or surface runoff, and understand how it moves, Dr Suren applied baits at about 20,000 times the average sow rate of 2kg of bait per hectare. He then simulated the effects of rainfall on the baits to measure how much of the toxin leached into surface and ground water.

“Interestingly, we found that 1080 leaches from baits at a constant rate, regardless of rainfall intensity,” said Dr Suren.

“Even more interestingly, we found that the overwhelming majority – over 99 per cent - of the toxin-laden rainwater goes straight into the soil rather than flowing overland into streams.”

Results of the soil water monitoring showed that observed concentrations (when corrected for the large number of baits applied over the small area) never exceeded one-third of the Ministry of Health drinking water standard of 3.5g/l (3.5 parts per billion). This suggests that the contamination of soil water from scattered, individual baits within a catchment during normal 1080 operations is likely to be so small that it may not even be detectable (analytical measurement limit, 0.1g/l).

More recent field work also monitored loss of toxin from baits under natural rainfall, and examined shallow groundwater and stream water. No traces of 1080 were found, despite a high application rate designed to maximize the chances of detecting it.

“From these results, we can conclude that the effects of 1080 leaching from baits into soil water and stream water are highly, highly unlikely to have any adverse effects on water quality,” said Dr Suren.

This study builds on previous research. In 2009, NIWA intensively sampled a West Coast stream after an aerial drop, to investigate the potential for short-term contamination from baits landing directly in the stream, and rainfall leaching 1080 from baits. Again, the results showed levels well below the MOH guidelines.

In 2011, the Parliamentary Commissioner for the Environment stated in her milestone report on 1080 that “1080 residues have never been recorded in public drinking water supplies.” She concluded that the use of 1080 was both safe and necessary.

The full research paper is expected to be published later this year.

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