Paul McNabb of the Cawthron Institute in Nelson explains what a mouse bioassay is. He describes the shortcomings of mouse bioassays and explains the need to develop other ways to detect toxins.
A mice bioassay is literally using a mouse to determine how safe a food is. We make an extract from the food and inject that directly into a mouse, and if the mouse survives, the food is safe, and if the mouse dies, the food is unsafe. But it doesn’t tell us why the food is unsafe, at what the level the food might be unsafe, and it is subject to the mouse dying for other reasons which are not related to food safety. Sometimes it can miss toxins, and also sometimes the test is positive but there’s no toxin in the food.
A mouse bioassay, it just gives you very simple information to tell you whether or not there’s potentially a toxin there. Because it is so unreliable, we have developed these new tests so we can get better information more quickly and much more accurately. So the decisions we make about whether or not to harvest shellfish are based on much better information, and they protect the public.
All of the mouse bioassays that we do in New Zealand are certified by the National Animal Ethics Committee, and I guess the whole research programme that we’ve had here– moving away from routinely using mice to asses the safety of food towards using LC-MS – has been based on this idea that we need to reduce the number of animals that we’re using for scientific research. And we’ve certainly achieved that, so previous to using LC-MS, we would’ve used 50–100,000 mice per year just to test shellfish, and we’re using none now.