Rights: University of Waikato. All Rights Reserved. Published 4 September 2012 Download

Paul McNabb explains LD50 – a lethal dose given to animals to determine the toxicity of a toxin. The graph in the clip shows the cumulative population response to increasing doses of a toxin.


One of the first things we do if we discover a new toxin is do something called an LD50, so it’s a lethal dose which kills 50% of the test animals. And that’s usually done initially by injection of a toxin into the mouse and then that would be followed by feeding the toxin to the mouse. It would be most common for toxins to be more potent when injected than when fed, and the difference between those different types of LD50 can tell us about the toxin, how much of a risk it may be.

And we’ve certainly had examples in the past where toxins that are very potent by injection are a lot less potent by feeding. And that means that, if we’re doing our mouse bioassays to check our food is safe by injection, we’re often overestimating the risk because the risk when the toxin is eaten is a lot less. So we incorporate that information about each toxin into our LC-MS test, and then that helps us assess by the LC-MS whether the food is safe or unsafe.