I'm not sure what the story is with dry ice. However, when I was flying back from ANC on Continental and had some fish I was bringing back with me the woman at the checkout counter interrogated me about whether or not I had any dry ice in with my fish. She made it very clear that I was not allowed to have dry ice with my fish and that they had ways of finding out if I was not telling the truth about there being no dry ice in with my fish.