"I'm a pediatrician and I can tell you birth control doesn't work 100 percent of the time," said Dr. Jim Diamond, the Sierra Club's biotechnology expert. "I don't see it working in trees either."
...from an article about bioengineered cottonwoods designed to clear mercury from contaminated brownfields, our pediatrician-cum- "biotechology expert" is worried about cross-fertilization by sterilized GMOs. Let me know how that mule out-breeding project works for you there, Dr. Diamond.
In all seriousness, the mercury cottonwood sounds like a deeply cool concept, and I can't imagine that a critter engineered with a handicap like "deliberately sequester heavy metal poisons" is going to be much of a threat to the general cottonwood gene pool. Sometimes environmentalists sound a bit like turn-of-the-century racists with their concerns about quick-breeding "mongrel races" out-competing their preferred race. If it's so damned superior, why wouldn't it have the evolutionary advantage, Mr. Social Darwinist/literal Darwinist/nature-worshipper?
Link via a bit of slumming in Fark.