The only two major cases of children being poisoned through candy were caused by their own family. However, there have been multiple occassions where sharp objects, such as needles, were found in Halloween candy. So you still shouldn't eat candy that's not in a sealed package, but at least it's probably not posioned. It's probably good to have poison control on speed dial just in case!
Click through for more spooky (but completely bogus) Halloween myths!