Experts suspect a variety of toxins could be linked to Gulf War Illness—from pesticides to the anthrax vaccine—but one likely culprit, Golomb says, is something that wasn’t an enemy weapon, or even an accidentally released chemical: the PB (pyridostigmine bromide) pill. The PB pill was given to troops by the U.S. Armed Forces in case of possible exposure to nerve agents—it was a preventative. The cure may have made them sick.