Supposably the "poison" was potassium
ferocyanide. Now possibly the new media got the story wrong but I believe potassium ferocyanide is not all that poisonous. I remember a chemistry professor once saying that one would take potassium ferocyanide as an antidote for conventional cyanide poisoning, i.e potassium cyanide. Supposably potassium ferocyanide binds to the same site on the hemoglobin molecule that cyanide would bind to but potassium ferocyanide does not interfer with blood oxygen exchange. I wonder if these terrorists were such idiots that they were trying to poison people with something that was nontoxic. It would be funny if it was true.

Gary