A new study indicates that St. Louis-based Monsanto’s best-selling weed killer is doing more than killing weeds. A University of Pittsburgh ecologist says his experiments indicate Roundup is much deadlier to amphibians than previously thought. In those experiments, Roundup killed nearly all the tadpoles in simulated shallow ponds. In a separate dry experiment, Roundup killed nearly 80-percent of the young frogs and toads after one day. Monsanto points out its directions advise that Roundup shouldn’t be used near bodies of water. Scientists, though, note that many amphibians live in shallow puddles and they worry that wetlands within fields and forests are accidently being sprayed.