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Transgenic Trees Spread Mercury Poisoning
Is moving mercury from place to place really remediation?
Prof. Joe Cummins asks.
Recently, researchers tested trees genetically modified to remove ionic
mercury from contaminated soil, then convert that to volatile elemental
mercury, which is released to the atmosphere. The researchers seem to believe
that the atmospheric mercury will be relatively harmless. The field tests were
undertaken in Danbury Connecticut and supported by the United States
Environment Protection Agency (EPA) and other interested parties [1]. Danbury
is the home of mercury-polluted sites originating from hat- making. Mercury
caused mercury poisoning in workers, who get the "Danbury shakes". The mercury
"remediation" project will, however, simply move the pollution to the
atmosphere, from which it will be redeposited over the cities of the Northeast
and the lakes and waterways of northern USA and Canada. Once deposited in the
waterways and streets of cities, elemental mercury will be converted by
microbes into organic mercury that will cause nerve damage and birth defects in
humans and animals alike.
Last year, I pointed out the dangers of this form of remediation for the
cities and waters of the United States and Canada [2]. But my comments were
completely ignored by the EPA bureaucrats and the biotechnology industry.
Worldwide, human activities resulting in emission of mercury is
estimated to be some 1900 tonnes, about three quarters from burning fossil
fuels, particularly coal. Waste disposal sites, cement manufacture and waste
incinerators made up the bulk of the remainder. Asian countries contribute over
half of the emission while Europe and North America contribute less than a
quarter. Gaseous elemental mercury makes up over half of the emitted mercury,
while divalent mercury and particulate mercury make up the rest [3]. The
emitted mercury tends to be deposited from the atmosphere in snow and rainfall,
posing serious threat to humans and animals because elemental mercury is
converted to ionic and organic mercury after ending up in the Arctic, in Canada
and Northeastern American cities [2,4]. If phytoremediation of mercury-polluted
sites were undertaken on a large scale in North America, the global emission of
mercury could double in less than a decade.
The mercury phytoremediation scheme is based on introducing a bacterial
gene merA into the genome of plants. For efficient genetic activity in
plants, a synthetic merA gene with altered DNA sequence is used to
modify plants [5-7]. Mercury-resistant microbes are also promoted as an
efficient and inexpensive treatment for mercury-polluted water [8]. But the
anticipated widespread application of such technology has not considered the
consequence of atmospheric-pollution from mercury remediation.
In conclusion, mercury remediation using phytoremediation and bacterial
remediation, both cause atmospheric release of elemental mercury, and is being
promoted by technologists and government regulators. Such "remediation" is no
remediation at all, it is just moving the problem from one place to another! In
fact, it is moving mercury from contained contaminated sites to the streets of
cities and the bodies of water that give us fish and drinking water.
- Williams P. UGA researchers involved in first trial using transgenic
trees to help clean up toxic waste site. University of Georgia News Release
Sept. 11, 2003 http://www.uga.edu/news/
- Cummins J. "GM trees alert"
Science in Society 2002,
16, p.33
- Pacyna E. and Pacyna J. Global emissions of mercury from
anthropogenic sources in 1995, Soil, Air and Water Pollution 2002, 137,
149-65
- Renneberg A and Dudas J. Transformation of elemental mercury to
inorganic and organic forms in mercury and hydrocarbon co-contaminated soils.
Chemosphere year? 45, 1103-9
- Rugh C, Wilde H, Stack N, Thompson D, Summers A and Meagher R.
Mercuric ion reduction and resistance in transgenic Arabidopsis
thanliana plants expressing a modified mer A gene. Proc. Natl.
Acad. Sci USA 1996, 93, 3182-7
- Heaton A, Rugh C, Wang N, and Meagher R. Phtoremediation of mercury
and methyl mercury polluted soils using genetically engineerd plants.
Journal of Soil Contamination 1998, 7,497-509
- Kramer U and Chardonnens A. The use of transgenic plants in
bioremediation of soils contaminated with trace elements. Applied
Microbiology and Biotechnology 2001, 55, 661-72
- Wagner-Dobler I. Pilot plant for bioremediation of mercury-containing
industrial wastewater. Appl. Microbiol Biotechnol 2003, 62, 124-33
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