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  • From: "Tradingpost" <tradingpost@gilanet.com>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Playing with our food
  • Date: Wed, 30 Nov 2005 19:08:35 -0700

http://www.commonground.ca/iss/0512173/cg173_gmo.shtml
Dec 2005
Playing with our food
by Pat Howard

Few rules exist in the food engineering game

Since 1995, I have studied the scientific debates regarding the
potential hazards of genetically modified plants, animals, and
micro-organisms. The concerns expressed by ecologists, agronomists,
microbiologists, veterinarians, physicians, toxicologists, and
immunologists in the scientific literature are considerable. Coverage
in the media, on the other hand, has been very inadequate.

The one study that received a brief flurry of media coverage was
conducted by a research team in Scotland, led by Dr. Arpad Pusztai, an
international expert on lectins, which are insecticidal molecules
produced by plants. In 1995, Pusztai’s team received a $3.2 million
research grant to investigate the safety of genetically engineered
potatoes producing such an insecticidal molecule. Pusztai had already
spent six years studying this lectin. He had fed it to rats in very
large quantities without any deleterious effects. He did not expect to
uncover any health hazards.

The rat-feeding study was meticulously designed to maximize the
reliability of the findings. One group of rats ate the genetically
modified potatoes, a control group consumed unmodified potatoes, and a
third group ate unmodified potatoes laced with the lectin. To
everyone’s surprise, the rats that ate the genetically modified
potatoes suffered serious health effects. The study used young, growing
rats.

After only 10 days, a significant number of the rats that ate the GM
potatoes showed signs of arrested development of their livers,
testicles, and brains. Some suffered damage to the thymus and spleen,
which are both crucial to immune system function. The rats’ white blood
cells also appeared to have been affected. The cells lining their
stomachs and intestines had begun to proliferate and undergo structural
change, an ominous sign of the possibility of an increased risk of
cancer. The feeding continued for 110 days, the equivalent of the first
10 years of a child’s life.

To rule out any other causes, the researchers repeated the tests with
boiled, baked, and raw potatoes and varied the amount of food and
percentage of protein. The results were consistent; the GM potatoes
alone damaged the young rats’ organs and immune systems. On October 16,
1999, The Lancet reported the study. Pusztai, however, went public with
his findings before publication in this peer-reviewed journal. He
appeared on television and expressed his concern for the public, which
was already eating genetically modified potatoes, tomatoes, corn
products, and soy. He was subsequently fired and his computer and
research data confiscated. He and his colleague Stanley Ewen later
obtained all the data and published their analysis in Britain’s most
prestigious medical journal.

Since the lectin did not damage the rats’ organs and immune systems,
what did? Is there something about the genetic modification process
itself that makes the feed immunogenic, toxic, or carcinogenic? Feeding
studies involving rats, mice, pigs, and cows, conducted in Mexico,
Brazil, Cuba, Japan, Egypt, Slovenia, and Russia have produced
comparable, negative health effects. In fact, a rat-feeding study of
the first commercial GMO, the FlavorSavr tomato, also revealed lesions
that caused FDA scientists to protest the agency’s approval of the
product in 1994.

How do genetic engineers manage to get foreign DNA into the genome of
a host plant and enable the plant to utilize it to produce proteins
that confer the ability to tolerate a particular herbicide or
antibiotic, or to kill insect pests? The fact is that they exploit the
infectious capacities of viruses and bacteria. One commonly used vector
is a soil bacterium, a plant pathogen that causes galls or tumours.
Only the DNA coding for proteins involved in inducing tumours is used.
It is taken from a plasmid; plasmids are small, free-floating circles
of DNA that provide bacteria a greater capacity to deal with
environmental changes than any other life form. They are able to
exchange and share plasmids, which contain genes for adaptive
capacities. This is how they spread antibiotic resistance. There is
evidence that antibiotics may function as sex hormones stimulating gene
transfer via the exchange of plasmids, among even different species of
promiscuous bacteria.

Genetic engineers open up plasmids and insert a set of genes borrowed
from other species. The ideal transformation would incorporate one copy
of the foreign gene set into the genome of the host plant’s cells.
However, this is rarely, if ever, what actually occurs. Most of the
approved commercial varieties have either only a portion of the foreign
DNA that was successfully transferred, or multiple copies of the
desired transgenic DNA. Recent research, after regulatory approval, has
revealed that unintended bits of bacterial DNA are frequently
incorporated, which may result in deletions, multiplications, or
movements of the host plant’s DNA.

The transformed configuration of DNA that characterizes the transgenic
plant’s genome is called the transformation event. After a long
struggle in Europe, regulators now require this information from
applicants seeking approval for the sale and growth of transgenic
varieties. Many of the varieties currently being analyzed by European
scientists are turning out to be other than what they are supposed to
be.

In 2003, government scientists in France reported on studies of five
transgenic crops: Monsanto’s Round-up Ready soybeans and four Bt
insecticidal corn varieties. All five transgenic lines had inserted
foreign DNA, whose structure was no longer the same as was originally
reported by the company.

Not only were the inserted genes rearranged, but the plants’ own
genomes had also been scrambled around the insertion site. Belgian
scientists also conducted similar studies that turned up comparable
evidence of DNA scrambling. This signifies that the precise varieties
evolving in fields in Canada, the US, China, Argentina, Australia, the
Philippines, and elsewhere have not been tested for potential
allergenic or toxic effects on the humans and animals that consume
them. If the lines are unstable, no amount of testing can guarantee
their safety in the future, or when they are subjected to different
environmental stresses.

Genetic engineers have no control over where their foreign DNA
constructs will be inserted into the host cell’s DNA. Research has
revealed that the insertions often occur inside or near genes, which
can be turned on or off by the invading foreign DNA. This can have
serious consequences.

Of particular concern are fragments of foreign DNA that appear in
virtually all genetically modified crops: the cauliflower mosaic virus
(CaMV) promoter is used to ensure that the foreign genes continue to
express their proteins at a high level. This viral gene switch, or
promoter, is able to stimulate the expression of genes, not only in
plant cells, but also in the cells of mammals, including humans. This
promoter is in all the cells of transgenic plants. Thus, the question
of whether it is broken down by digestion processes, or ends up in cows
milk, or in the muscles and blood of animals fed GM feeds, or in the
milk of breast-feeding mothers, becomes a really important issue.

When critical scientists have raised these concerns, proponents have
responded that we have been eating cauliflower, which is sometimes
infected with this virus, for a very long time with no apparent
consequences. However, the cauliflower mosaic virus promoter used in
genetic engineering is, in its naked form, unlike the natural wild-type
virus that has a protective protein coat. The naked forms of viruses
are more infectious because their viral coats generally determine host
specificity. CaMV promoter is particularly prone to integrate into host
cell genomes because it has a recombination hotspot, meaning it is
prone to breaking and joining with other DNA at that spot. This
increases the likelihood that the promoter, and any other genes linked
to it, will be integrated into the genomes of cells they manage to
enter. Cancer could be one of the outcomes in cells in which genes are
turned on and kept on by this particularly strong promoter.

Throughout all GM crops, another hazard of this viral promoter is its
potential to reactivate dormant viruses, which exist in the genomes of
all higher organisms, including plants and animals. There is also a
danger of the creation of new viruses by recombination. Yet another
concern is the use of antibiotic resistance marker genes that could
conceivably transfer resistance to bacteria in the mouths and guts of
people and animals that ingest GM food and feed. It could also be
transferred to bacteria in soil that surrounds the roots of transgenic
plants, or soil that contains decomposing GM crop residues. Soil
containing such bacteria could be dangerous for farmers and children,
who might end up passing the resistance to bacteria resident in their
own bodies. If pathogenic bacteria later infect them, antibiotics may
prove useless because of transfer of the resistance gene from their
resident bacteria to the pathogenic invader.

Concern about this possibility prompted the British Medical
Association to call for a moratorium on field trials or
commercialization of GM crops containing these genes. The European Food
Safety Authority has also recommended that no crops containing
antibiotic resistance marker genes be approved anywhere in Europe. Many
of the crops growing in Canada carry these antibiotic resistance genes
in every cell of the plant.
Safety assessments are necessary to determine whether these genes are
present in soil bacteria, or in bacteria in the mouths, stomachs, and
intestines of people who have been eating genetically modified foods.
One major problem we face is the underdeveloped state of safety
assessment science. We can only culture less than one percent of
bacterial species found in soil, and in our own bodies. Is there any
evidence of lesions in our digestive organs, especially in those of
babies and young children? What about their immune systems and their
livers and brains? If the foods are not even labelled, how can we know
whether what we are eating and feeding our infants and children is
harmful?

In 2004, people living near a field of Bt corn in the Philippines
developed respiratory and gastric illness when the corn flowered. Tests
of their blood revealed antibodies to the Bt toxin in the corn pollen,
which suggested that it might have caused the illnesses. In Germany,
between 2001 and 2002, 12 cows, illegally fed a steady diet of Bt corn,
mysteriously died. Milk from the herd was tested and found to contain
the genes for the bacterial Bt toxin. Neither Canada nor the US
conducts tests on milk from cows fed GM feed for the presence of
bacterial toxin or viral promoter DNA. How can we know if GM plants are
producing dangerous allergens or toxic metabolites as a result of
disruptions of plant genomes caused by the insertion of foreign DNA? We
are part of one enormous feeding experiment in which none of us have
given informed consent.
-------
Pat Howard is associate professor of communication at Simon Fraser
University. She teaches courses on scientific controversies and
government regulation related to genetic engineering.




  • [Livingontheland] Playing with our food, Tradingpost, 11/30/2005

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