KEY POINTS:
A huge aerial rat-bait drop planned for two Hauraki Gulf islands next winter will put children at risk and employs a distribution method banned in the United States, says an environmental watchdog group.
Bob Tait, co-director of Friends of the Earth, told the Herald that the up to 170 tonnes of brodifacoum to be dropped on Rangitoto and Motutapu would take months to lose its potency, yet the Department of Conservation planned to ban the public from the islands for just one week.
Mr Tait said the Environmental Protection Agency in the United States had recently introduced new safety measures to protect children from accidental exposure to rodent-control products.
The measures would also reduce the risk of accidental poisonings of pets and wildlife.
In the case of brodifacoum, it would no longer be able to be spread as loose bait outdoors. Instead, it could be used only in bait stations.
Mr Tait said as little as one milligram of brodifacoum could produce clotting disorders in adult humans, and when that was scaled down for children it would require them to eat only about four baits to produce similar symptoms.
He said the baits were coloured like bright lollies and pointed out that children were known to eat even dirt.
"There is real risk to any young children who are on the islands at any time they are surrounded by a blanket deposit of poison baits."
He said DoC planned to close the two islands to the public for just one week, whereas one month's closure would be far safer.
Richard Griffiths, manager of DoC's Rangitoto/Motutapu pest eradication project, said it would require a child to eat dozens of the baits to die from the poisoning.
He said although the poison could stay active for up to four months the pellets, which did not look palatable, disintegrated in the rain very quickly.
There would be a huge publicity campaign, with signage on all access points to the islands, education on ferries, and warning messages using the media.
The bait drops were planned for winter when visitor numbers were lower anyway.
Mr Griffiths said that in similar poisoning programmes on public land there had been no reports of humans being accidentally poisoned.
He said there was no other practical way of spreading the bait through the islands, which have a combined size of more than 3800ha, and parts of Rangitoto are very steep and not able to be accessed by foot.
Mr Griffiths said it had been estimated it would take at least 500 people to place the pellets in bait stations.
The plan was to close the islands to the public for a week after each poison application, and there might be up to three applications.
Most ground-feeding birds at risk of eating such baits were not present on the islands, he said, and it had been shown that for other bird types, their numbers increased once rats were removed.
Provision was being made to protect the small number of New Zealand dotterel on Motutapu.
Resource consent was being sought from the Auckland Regional Council and Auckland City Council.
