I think (someone please correct me if I am wrong) that dioxin builds up in your body a bit like mercury.
Dioxin is the "nasty" in things like Agent Orange (used in the Vietnam war) and the weedkiller 2,4,5T and one of the most noticable effects is birth defects. However, as is usually the case, proving that the dioxin came from the milk cartons or from where ever can be just about impossible in a court of law (as a lot of Vets have discovered
)