The anti-frankenfoods people have been arguing for years that sooner or later, a genetically modified food would behave in some unexpected and creepy fashion. It looks like researchers have documented the first case of this: A pest-resistant GM pea has been found to make mice sick when they eat it.

Researchers at Australia’s national research organisation, CSIRO, genetically altered a pea so that it expresses a protein — normally found in the common bean — that can kill pea-weevil pests. Normally this protein doesn’t cause any problems when eaten by mice.

But when expressed in the pea, the protein took on some unexpected properties — and when the mice ate it they suffered an allergic reation. Even spookier, as The New Scientist notes …

… the effect was the same whether the protein was taken from raw or cooked peas — so whether the protein was active or denatured. “To my knowledge, this is the first description of inducing experimental inflammation in mice” with a GM food, Foster says.

Because this research was publicly funded, it was published in a peer-reviewed journal. But as one of the researchers pointed out, experiments like this go on all the time in private labs, which virtually never publicize negative results — so who knows how many other experimental genetically-altered foods have caused similar adverse reactions.

(Thanks to Erik Weissengruber for this one!)