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The conclusion explores what host Edward Norton calls "the delicate interplay of chemicals and their ability to alter living systems." This can wreak environmental havoc underwater. In the U.S., biologists have found hermaphrodite frogs. Whales in Canada's St. Lawrence River have disturbingly high cancer rates. And in Australia, farm runoff has harmed the Great Barrier Reef. But there's hope: One Georgia geneticist is developing toxin-eating plants.