Is radiation good for you? Or dioxin? Or Arsenic? The answer is yes, but only in very small doses, says one of the country's most respected toxicologists. If he's right, environmental regulation will never be the same. Any idiot should be able to poison a plant. That is what Edward Calabrese thought in 1966 as a junior at Bridgewater State College in Massachusetts. He was in a plant physiology class at the time, and his lab group had been told to dose some peppermint with an herbicide called Phosfon. The idea was to measure how much a given dose stunted...