BHA/BHT falls under the artificial preservative category. They are known to cause cancer, and you should avoid feeding your hedgehog any foods containing them. Ethoxyquin is another preservative that falls under this category. Hedgehogs are prone to cancer anyway, feeding them any of those increases the risk of them developing problems.
Take a look at this list for other toxic things to hedgehogs: http://hedgehogcentral.com/forums/viewtopic.php?f=5&t=40&p=54