Poisons used to control animal pests are also called vertebrate toxic agents or VTAs. They include brodifacoum, cyanide and 1080 which are the main vertebrate toxic agents used in New Zealand to kill possums and other pests. Product labels give clear directions on use and these must be followed. There are also requirements for signage in areas where poisons have been laid.
Labels say whether the poison may be laid free (meaning that it’s not inside a bait station) or must be in bait stations. Brodifacoum used commercially for possum control must be laid in a bait station and can only be dropped from the air on islands. Some of these poisons, including brodifacoum and similar chemicals such as bromodialone and flucoumafen, are also available in small pack sizes for unrestricted sale to the public for rodent control and must be used in bait stations.
The way poisons are laid or the type of baits used mean that only the target pest animals should be able to easily access and eat the poison. Wild pigs occasionally get access to baits but more often scavenge on poisoned dead or dying possums or rodents and are exposed to (and can accumulate) the toxin. Each poison persists in animals for varying times. Brodifacoum lasts many months or even years in wild pigs and other animals that have eaten some of the poison (but not enough to kill them). It doesn’t break down when the meat is cooked – it is for this reason that MPI recommends not eating the offal of wild animals. On the other hand, 1080 is very soluble in water and is leached out of baits with rainfall, and very quickly degrades in the open and in the animal.
Hunting of wild animals for commercial trade is tightly controlled in New Zealand to ensure that meat produced from wild animals meets human consumption standards, which include residue requirements. As an added safety measure, wild animals that go to a game processor always have the offal condemned because some poisons can concentrate in internal organs. Hunters are required to know where and when poisons are laid and to provide evidence that the areas they hunted in did not have poisons laid.
Recreational hunters should also ensure that they know if the area they are hunting in has had poisons laid and, if so, avoid hunting there. There is an unknown risk of toxic residues in wild animals caught or shot in areas where poison baits have been laid. No assurances can be given for the safety or suitability for consumption of wild animals caught as part of recreational catch in risk areas.
Although there are no known cases of ill health directly linked to eating wild animal meat contaminated with poisons, residues of some poisons have been found in the offal of culled wild pigs and may pose a potentially serious food safety risk in recreationally-hunted wild animals. You should also be aware that recreational catch meat has not been subjected to any hygiene or processing standards, control or inspections.
Recreational hunters should take note of signage, and follow caution periods and buffer zones. Our advice is to discard offal and not eat it or feed it to dogs or other animals. There is advice on these and other aspects of hunting food safety in the booklet ‘Food safety for recreational hunters’ and in the accompanying wild food safety DVD.
The risk of a farm animal eating poison, then being slaughtered for food before the residues have depleted to undetectable levels is extremely low. Poison product labels clearly state how and where the product can be used. Labels include directions on placement of the poison and stock management to ensure that animals have no access to the poison. In addition, any unhealthy animal sent to a meat works is inspected by a veterinarian and would not get slaughtered for meat. None of our tests of meat from commercially farmed animals has detected any residues of vertebrate toxic agents.
There are food safety requirements around the use of commercially-hunted animals in pet food. As with food for humans, pet food for sale must be fit for purpose and there are requirements for both hunters and pet food processors.
For recreationally hunted game, no guarantees can be given about the safety of wild animals used as pet food. Dogs in particular are very susceptible to 1080 poisoning and pets/working animals should not be fed meat from wild animals that may have been exposed to this or any other poison.
MPI operates poison testing programmes on carcasses from wild animal processing premises and hunters must supply evidence as to wild animal procurement to these premises. If a certified supplier is found to have supplied wild animals contaminated with poisons, or they have not complied with procurement requirements, they may be removed from the list of Certified Suppliers. In addition, their name may go on the National Residue Surveillance List so that any product they supply in future will be intensely tested. They could also face prosecution. Recreational hunting is not regulated so there is no residue testing requirement in place for recreational catch.
If you, your family or pets/working dogs are eating meat from wild animals you should make sure that you are hunting in an area where poisons have not been laid. If you hunt on private property you should check with the owner of the property if any poisons have been laid. If so, avoid hunting in that area because animals that have been exposed to poisons can travel for some distance and may not display any effects of the poison for some time after exposure. If you hunt on Crown land, check the current DoC Pesticides Summary to see if any poisons have been laid. As an added margin of safety, you are also advised to discard all offal from wild animals and not to feed it to dogs or other animals.