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Monday, Nov 9, 2009
Genetically modified plants and microbes that gobble up pollution sound like a great idea. But who will clean up after the cleaners?
Aug 28, 2003 | It's a kind of Superfund superplant, a leafy organism designed specifically to devour the hazardous waste that industrial machinations and human carelessness have left in the ground.
The genetically modified mutant plants suck heavy metals, such as lead and arsenic, out of the soil into their roots, stems and leaves, cleansing the contaminated soil. It's an intoxicating vision: Imagine fields of these valiant plants fighting part of the $700 billion battle that the United States faces in mopping up polluted Superfund sites.
This green-dream promise may have moved a bit closer to reality, according to research announced by a group of biologists at the University of California at San Diego. The researchers found that in modifying a mutant variety of Arabidopsis, a relative of the mustard plant, the plants would detoxify and suck up several common heavy metals into their stems and leaves. Four of the top six heavy metals found at Superfund sites -- lead, arsenic, mercury and cadmium -- are among those the plants can ingest, reported the researchers in the Aug. 19 issue of the Proceedings of the National Academy of Sciences.
The lure of bioremediation -- the practice of using organisms to restore damaged or contaminated areas -- is that toxic cleanup can be done more safely and for less money than by traditional means.
"Right now, the standard technology is to dig soil up, put it on trucks. You've just moved it from point A to B. Hopefully you're picking a site with less groundwater problems," says Julian Schroeder, a biology professor at UC-San Diego, who led the team of researchers working on the plants. "What bioremediation engineers would prefer is if you could go in such a field and simply cut the plants off and harvest the toxins. You wouldn't have to dig up soil and create a lot of dust, which, if there are toxic metals in there you wouldn't want to do."
The scientists found that phytochelatins -- chemicals produced by an enzyme whose gene the lab co-discovered four years ago -- allow the metals to move through the plant, up from the roots to the shoots for easier harvesting.
The UC-San Diego research is still very much taking place in the lab, and not out on actual toxic-waste sites, but it suggests the kind of hope that genetically modified organisms might hold for cleaning up the damage that humans have inflicted on their environment. At the same time it poses a dilemma for environmentalists, who have been wary of any form of genetically modified organism that might escape its boundaries and end up harming surrounding ecosystems. As scientists get closer to making bioremediation a working reality, a question that few are asking is becoming more important: Who will clean up after the cleaners?
Will environmentalists and federal regulators embrace these new creations, or will they decide that tinkering with the balance of Mother Nature is just too risky?
