Proponents of GM crops are always trotting out the tired (and utterly illogical) argument that because there's no proof that bioengineered plants do any harm, there should be no laws prohibiting their use.
Someone should refer them to last week's Proceedings of the National Academy of Sciences. Indiana University's Todd Royer authored a paper showing that toxic Bacillus thuringiensis genes spliced into corn to repel insect pests can wash into ponds and streams, killing beneficial caddisflies, which are important food sources for fish and amphibians. In barnyard parlance, the study might be a case of closing the door after the cows have gotten out: Around 35 percent of American corn is already genetically modified.