Super trees that suck up and destroy toxic chemicals from the air and water faster than regular trees are the latest creation by scientists at the University of Washington.

When the scientists stick a rabbit gene into poplar trees, the trees become dramatically better at eliminating a dozen kinds of pollutants commonly found on poisoned properties.

The trees could prevent the need for digging up tons of soil or pumping out millions of gallons of water for treatment and disposal. They naturally render a list of cancer-causing pollutants — benzene, trichloroethylene (TCE), vinyl chloride, chloroform — non-toxic.

But while the poplars could benefit cleanup projects, they raise a multitude of ecological and ethical concerns.

Many people are worried about transgenic organisms, in which a gene from one species is inserted into another, whether it’s corn that produces a pig vaccine or a soybean that makes its own pesticide. There are concerns that mutant plants could spread, entering the food supply and threatening human health. Or they could interbreed with normal plants, transferring herbicide resistance to weeds, for example. No one can predict all of the potential side effects of a new gene on the host plant or other plants and animals.

When it comes to the pollution-consuming poplars, “it’s really a question of trading some of the unknown risks of planting genetically modified trees with the positive environmental benefits,” said Andrew Light, a UW professor of philosophy and public affairs. “This is a real dilemma for the environmental community.”

In the UW project, a gene from a rabbit is added to the poplar’s DNA. The gene contains the instructions for an enzyme that breaks down pollutants. A very similar enzyme naturally exists in the plant, but scientists have not been able to isolate the poplar’s version in order to boost its production.

“It’s a beautiful thing that a rabbit gene is perfectly readable by a plant. Look at how connected life is,” said Sharon Doty, a professor with the UW’s College of Forest Resources. She’s the lead author of the poplar research published Monday in The Proceedings of the National Academy of Sciences.

“It’s a beautiful thing,” she said. “I don’t think it’s something to fear.”

Others are not so smitten.

“It’s commendable to be thinking about finding ways to reverse some of the pollution that has been caused in the past, but in doing so we have to make sure we don’t cause new problems at the same time,” said Doug Gurian-Sherman, a Washington, D.C.-based senior scientist with the Union of Concerned Scientists.

“There are a lot of unknowns here,” he said.

Non-edible transgenic plants have captured little public attention — with the notable exception of the attack on the UW’s Center for Urban Horticulture six years ago. A group of eco-terrorists firebombed the center in an effort to sabotage research on genetically modified poplar trees by a researcher who is not part of Doty’s study.

Doty said researchers remain worried about the threat of attack, but hope people understand the potential benefits of their work.

There are other experiments under way nationwide with trees and plants genetically modified to help with pollution cleanup — cottonwoods with an unusual affinity for mercury, Indian mustard plants that soak up selenium.

The poplars created by the UW scientists are unique for being able to remove and destroy “several of the most widespread and dangerous pollutants.” But that versatility also could prove problematic. Because the enzyme is unusually flexible and able to attack multiple chemicals, there’s a greater likelihood that it might affect the trees and other organisms in unexpected ways.

There are still years of research ahead before the first of these poplars could be tested on an actual contaminated site. The results showing speedier destruction of toxics compared with normal trees — TCE 53 times faster, benzene 10 times faster, chloroform nine times faster — come from poplars only a few inches tall that are grown in solutions in the lab.

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