Southern trials test sodium nitrite on possums

Poison baits using sodium nitrite as a toxin are being tested on possums at a secret site in the South Island.

Environmental regulators last month gave Auckland company, Connovation Ltd, approval to manufacture 15kg of the poison baits at its East Tamaki premises and to ship them to the South Island for the field trials on possums.

Details of where the trials are being conducted and the outlines of study on the poisons, NNPAS-C1 and NNPAS-C2, were only supplied to the Environmental Risk Management Authority (ERMA) in a confidential paper.

"Access by the public is limited and there is no domestic stock on the site," Erma said.

Signs on the trial would warn people that might be in the area of the green baits set along 12 lines, each with 10 bait stations.

Uneaten bait would be sent to a waste management company, and dead animals either buried of frozen and also sent to a waste company or incinerated. Tests on the two formulations before and after the poisoning trials will indicate their relative stability in the environment, as a guide to which one should be most useful.

Connovation is part of a joint research programme with Lincoln University seeking "smart pest control" for animals such as rodents, weasels, ferrets and stoats, feral cats and possums.

The researchers are seeking humane and cost-effective technologies that target multiple pest species with minimal non-target side-effects.

Overdoses of sodium nitrite can not only poison animals but cause mutations in their offspring.

In much smaller doses, the chemical has been widely used as a colour fixative and preservative in meats and fish.

- NZPA