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The Watery Fate of 1080

Continuing possum control operations around Mt Taranaki have sparked debate as to the possibilities of water contamination by the 1080 poison used, but a comprehensive survey by Landcare Research scientists has shown no sign of the poison in the water systems. Last year, 162 surface and ground water samples were taken over a four-month period following the 1080 drop.

"Sodium monofluoroacetate [1080] could not be detected at a quantifiable level in any of the water samples despite our laboratory using a gas chromatographic electron capture detector method with a limit of detection of 0.0003 ppm [parts per million]," says toxicologist Dr Charles Eason.

"Although these water monitoring programmes indicate that significant contamination of waterways is unlikely, we need to more clearly understand how 1080 breaks down in water and to model any consequences of 1080 contamination in waterways," he says.

Landcare researchers have been studying this problem, looking at how fast 1080 degrades under various water environments. The lower the water temperature, the longer it took the 1080 to be metabolised by the bacteria and fungi present. In the aquarium studies, 1080 was found to be eliminated within two to four days. Any fluoride ions released by the breakdown were well below the limit acceptable for human drinking water, at around 0.07 ppm compared to 1 ppm respectively. Stream flow in the natural environment would further dilute this.

Other studies have shown little or no problem with 1080 contamination of water supplies. An Otago poison drop for rabbit control produced a 1080 measurement of 0.0003 ppm of stream water. Eason says that a 60-kilogram human would need to drink 200,000 litres at one sitting in order to receive a fatal dose.

Even so, Eason notes that many people would still find any level of contamination unacceptable, and that considerable care has to be taken in possum and rabbit control operations.