Just over a year ago, a research team at Tulane University in new Orleans published some startling results. The group reported that pesticides were hundreds of times more toxic in pairs than one at a time. Such synergistic effects had been reported before, but the staggering magnitude reported caught researchers around the world by surprise. Then last month Professor McLachlin withdrew the study, saying he could not replicate the results. Steve talks with Living on Earth’s Dan Grossman about what happened.