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There's not a lot of good chewing tobacco or smoking cigarettes can do for
your health. But, as this ScienCentral News video reports, one researcher
says genetically modified tobacco may do some good by cleaning up some
polluted military sites, June 2005 .

Reuniting tabacco and the military

Cigarettes were once considered a "necessary comfort" for soldiers at war.
That's not the case anymore, now that the Surgeon General's warnings and
anti-smoking campaigns caution everyone about the health hazards of smoking.
But scientists may be on the road to reuniting tobacco and the military.
They're designing genetically modified tobacco plants that could one day
help clean up some polluted military facilities.

The military uses the explosives TNT and RDX (an explosive more widely used
than TNT) to fire shells and bombs. After an explosion, residual TNT and RDX
particles scatter the target area. When it rains, they can seep into the
soil and groundwater. The primary way these sites are cleaned up is by
calling in backhoes, digging up the dirt, and trucking it off to be burned.
Cleaning up the groundwater requires additional filtration systems. All of
it leaves the military paying hundreds of millions of dollars each year in
clean up costs.

"It's a very, very expensive process to dig up [contaminated] soil and
incinerate it," says plant biologist Neil Bruce , "So we're trying to
develop methods by which we can remove those explosives from soil using
plants and microorganisms."

Now, researchers lead by Bruce at England's University of York say
genetically modified tobacco plants may prove to be a cheaper way to clean
up polluted firing ranges, munitions dumps, and even post war zones.

Bruce told the 2005 American Association for the Advancement of Science
meeting in Washington D.C., that his research team transferred genes from
toxin-eating bacteria into tobacco plants, and these genetically modified
plants ? also called transgenic plants because they contain genes from two
different organisms ? grew faster in toxic TNT and RDX laboratory solutions
than normal plants did. He also reported that his plants broke down toxins
faster than regular plants.

Transgenic tobacco plants capable of treating TNT contamination function
slightly differently from plants designed to treat RDX. The tobacco plants
used to treat TNT basically transform TNT's molecular structure into a
nontoxic form, while the plants that can dissolve RDX gradually pull
nitrogen groups ? molecular units of nitrogen and oxygen ? from the
explosive until it eventually falls apart. The plants then use the nitrogen
groups as food to grow.

Bruce says creating plants that can breakdown RDX is particularly important
because it can spread through soil and groundwater much more quickly than
TNT, which can mean multimillion dollar clean up efforts.

Using plants to clean up contamination is not a new idea. In fact the
military is using a variety of wetland plants, fungi, and poplars, to clean
up sites polluted with heavy metals, PCB s, chlorinated solvents, and
petroleum products, among other things. U.S. Army Environmental Center
spokesman Robert DiMichele says that in certain circumstances it's a
"process that has worked extremely well," and has proved less expensive.

The researchers say bio-remediation projects can sometimes be as much as ten
times cheaper than digging, hauling, and filtering out contaminants. But
DiMichele says it "can take decades as opposed to a few years" to complete
the clean up process.

However, none of the military sites use genetically modified plants and as
Bruce points out, "Traditional plants are unable to degrade explosives. They
may take them up, but once the plant dies, the toxin just literally goes
back into the soil again."

The spoils of war?

The research naturally raises questions about whether the technology could
be applied to other types of plants in different climates where tobacco will
not grow and whether it would work in post-war zones. While the technique is
the same one used to genetically modify other crops, like corn for example,
Bruce says designing various plants capable of degrading explosives in
different climates is still in the future. In his research, tobacco served
only as a model, they do not have the skills, or what Bruce calls the
scientific "tool box," to apply it to all plants and climates yet.

Furthermore, DiMichele says it's not appropriate for places like Iraq where
there are more immediate needs. He says in Iraq, the "primary concern has
been to clean up the unexploded bombs."

Bruce's colleague, University of Washington forester Stuart Strand , says
the best place for the tobacco plants would be on active firing ranges,
where it's obviously too dangerous to have cleanup crews working, and where
the transgenic tobacco plants could provide "continuous treatment." But he
says there is a lot more research that needs to be done before there is an
established "beneficial effect outside the training range."

"One of the main concerns of genetically modified plants is the problem of
gene transfer," says Bruce. "What happens if the genes get out into the
environment, and what effect would it have on native species?"

Bruce doubts there would be any severe consequences because so many of the
contaminated sites where the transgenic tobacco could be planted are so
toxic that the plants could only have a beneficial effect. Still he says,
"We've probably got another four or five years worth of science and trial
within greenhouses," says Bruce.

This research was presented at the 2005 American Association for the
Advancement of Science meeting and was funded by the Strategic Environmental
Research & Development Program of the U.S. Department of Defense .

[www.sciencentral.com]

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