tenderpaw's 4yo son gets cranky, nasty, and even violent when he's had HFCS. There's a remarkable difference in his behavior when he has and hasn't had it. Even I, a non-kid person, can see it as clear as day. She's changed his diet to reduce, and preferably eliminate, HFCS as much as possible.

Now, whether mercury has anything to do with this or not, I don't know.