http://www.organicconsumers.org/2006/article_637.cfm
Genetically Engineered Crops May Produce Herbicide
Inside Our Intestines

By Jeffrey M. Smith
Spilling the Beans/Institute for Responsible Technology

Pioneer Hi-Bred's website boasts that their genetically modified (GM)
Liberty Link corn survives doses of Liberty herbicide, which would
normally kill corn. The reason, they say, is that the herbicide
becomes "inactive in the corn plant." They fail to reveal, however,
that after you eat the GM corn, some inactive herbicide may become
reactivated inside your gut and cause a toxic reaction. In addition,
a gene that was inserted into the corn might transfer into the DNA of
your gut bacteria, producing long-term effects. These are just a
couple of the many potential side-effects of GM crops that critics
say put the public at risk.

Herbicide tolerance (HT) is one of two basic traits common to nearly
all GM crops. About 71% of the crops are engineered to resist
herbicide, including Liberty (glufosinate ammonium) and Roundup
(glyphosate). About 18% produce their own pesticide. And 11% do
both. The four major GM crops are soy, corn, cotton and canola, all
of which have approved Liberty- and Roundup-tolerant varieties.
Herbicide tolerant (HT) crops are a particularly big money-maker for
biotech companies, because when farmers buy HT seeds, they are
required to purchase the companies' brand of herbicide as well. In
addition, HT crops dramatically increase the use of herbicide, which
further contributes to the companies' bottom line.

There are no required safety tests for HT crops in the US-if the
biotech companies declare them fit for human consumption, the FDA has
no further questions. But many scientists and consumers remain
concerned, and the Liberty Link varieties pose unique risks.

Liberty herbicide (also marketed as Basta, Ignite, Rely, Finale and
Challenge) can kill a wide variety of plants. It can also kill
bacteria, fungi and insects, and has toxic effects on humans and
animals. The herbicide is derived from a natural antibiotic, which is
produced by two strains of a soil bacterium. In order that the
bacteria are not killed by the antibiotic that they themselves
create, the strains also produce specialized enzymes which transform
the antibiotic to a non-toxic form called NAG (N-acetyl-L-
glufosinate). The specialized enzymes are called the pat protein and
the bar protein, which are produced by the pat gene and the bar gene,
respectively. The two genes are inserted into the DNA of GM crops,
where they produce the enzymes in every cell. When the plant is
sprayed, Liberty's solvents and surfactants transport glufosinate
ammonium throughout the plant, where the enzymes convert it primarily
into NAG. Thus, the GM plant detoxifies the herbicide and lives,
while the surrounding weeds die.

The problem is that the NAG, which is not naturally present in
plants, remains there and accumulates with every subsequent spray.
Thus, when we eat these GM crops, we consume NAG. Once the NAG is
inside our digestive system, some of it may be re-transformed back
into the toxic herbicide. In rats fed NAG, for example, 10% of it was
converted back to glufosinate by the time it was excreted in the
feces. Another rat study found a 1% conversion. And with goats, more
than one-third of what was excreted had turned into glufosinate.

It is believed that gut bacteria, primarily found in the colon or
rectum, are responsible for this re-toxification. Although these
parts of the gut do not absorb as many nutrients as other sections,
rats fed NAG did show toxic effects. This indicates that the
herbicide had been regenerated, was biologically active, and had been
assimilated by the rats. A goat study also confirmed that some of the
herbicide regenerated from NAG ended up in the kidneys, liver,
muscle, fat and milk.

More information about the impact of this conversion is presumably
found in "Toxicology and Metabolism Studies" on NAG, submitted to
European regulators by AgrEvo (now Bayer CropScience). These
unpublished studies were part of the application seeking approval of
herbicide-tolerant canola. When the UK government's Pesticide Safety
Directorate attempted to provide some of this information to an
independent researcher, they were blocked by the company's threats of
legal action. The studies remained private.

Toxicity of the herbicide

Glufosinate ammonium is structurally similar to a natural amino acid
called glutamic acid, which can stimulate the central nervous system
and, in excess levels, cause the death of nerve cells in the brain.
The common reactions to glufosinate poisoning in humans include
unconsciousness, respiratory distress and convulsions. One study also
linked the herbicide with a kidney disorder. These reactions
typically involve large amounts of the herbicide. It is unclear if
the amount converted from GM crops would accumulate to promote such
responses or if there are low dose chronic effects.

Perhaps a more critical question may be whether infants or fetuses
are impacted with smaller doses. A January 2006 report issued by the
Environmental Protection Agency's (EPA) Office of Inspector General
said that studies demonstrate that certain pesticides easily enter
the brain of young children and fetuses, and can destroy cells. That
same report, however, stated that the EPA lacks standard evaluation
protocols for measuring the toxicity of pesticides on developing
nervous systems. Scientists at the agency also charged that "risk
assessments cannot state with confidence the degree to which any
exposure of a fetus, infant or child to a pesticide will or will not
adversely affect their neurological development." Furthermore, three
trade unions representing 9,000 EPA workers claimed that the
evaluation techniques used at the agency were highly politicized.
According to a May 24, 2006 letter to the EPA's administrator, the
unions cited "political pressure exerted by Agency officials
perceived to be too closely aligned with the pesticide industry and
former EPA officials now representing the pesticide and agricultural
community."

Although the EPA may be hampered in its evaluations, research has
nonetheless accumulated which suggests that glufosinate carries
significant risks for the next generation. According to Yoichiro
Kuroda, the principal investigator in the Japanese project entitled
"Effects of Endocrine Disrupters on the Developing Brain,"
glufosinate is like a "mock neurotransmitter." Exposure of a baby or
embryo can affect behavior, because the chemical disturbs gene
functions that regulate brain development.

When mouse embryos were exposed to glufosinate, it resulted in growth
retardation, increased death rates, incomplete development of the
forebrain and cleft lips, as well as cell death in part of the brain.
After pregnant rats were injected with glufosinate, the number of
glutamate receptors in the brains of the offspring appeared to be
reduced. When infant rats were exposed to low doses of glufosinate,
some of their brain receptors appeared to change as well.

Glufosinate herbicide might also influence behavior. According to
Kuroda, "female rats born from mothers that were given high doses of
glufosinate became aggressive and started to bite each other-in some
cases until one died." He added, "That report sent a chill through
me."

Disturbing gut bacteria

If the herbicide is regenerated inside our gut, since it is an
antibiotic, it will likely kill gut bacteria. Gut microorganisms are
crucial for health. They not only provide essential metabolites like
certain vitamins and short fatty acids, but also help the break down
and absorption of food and protect against pathogens. Disrupting the
balance of gut bacteria can cause a wide range of problems. According
to molecular geneticist Ricarda Steinbrecher, "the data obtained
strongly suggest that the balance of gut bacteria will be affected"
by the conversion of NAG to glufosinate.

When eating Liberty Link corn, we not only consume NAG, but also the
pat and bar genes with their pat and bar proteins. It is possible
that when NAG is converted to herbicide in our gut, the pat protein,
for example, might reconvert some of the herbicide back to NAG. This
might lower concentrations of glufosinate inside of our gut. On the
other hand, some microorganisms may be able to convert in both
directions, from glufosinate to NAG and also back again. If the pat
protein can do this, that is, if it can transform NAG to herbicide,
than the presence of the pat protein inside our gut might regenerate
more herbicide from the ingested NAG. Since there are no public
studies on this, we do not know if consuming the pat gene or bar
genes will make the situation better or worse.

But one study on the pat gene raises all sorts of red flags. German
scientist Hans-Heinrich Kaatz demonstrated that the pat gene can
transfer into the DNA of gut bacteria. He found his evidence in young
bees that had been fed pollen from glufosinate-tolerant canola
plants. The pat gene transferred into the bacteria and yeast inside
the bees' intestines. Kaatz said, "This happened rarely, but it did
happen." Although no studies have looked at whether pat genes end up
in human gut bacteria, the only human GM-feeding study ever conducted
did show that genetic material can transfer to our gut bacteria. This
study, published in 2004, confirmed that portions of the Roundup-
tolerant gene in soybeans transferred to microorganisms within the
human digestive tract.

Since the pat gene can transfer to gut bacteria in bees, and since
genetic material from another GM crop can transfer to human gut
bacteria, it is likely that the pat gene can also transfer from
Liberty Link corn or soybeans to our intestinal flora. If so, a key
question is whether the presence of the pat gene confers some sort of
survival advantage to the bacteria. If so, "selection pressure" would
favor its long term proliferation in the gut.

Because the pat protein can protect bacteria from being killed by
glufosinate, gut bacteria that take up the gene appears to have a
significant survival advantage. Thus, the gene may spread from
bacteria to bacteria, and might stick around inside us for the long-
term. With more pat genes, more and more pat protein is created. The
effects of long-term exposure to this protein have not been
evaluated.

Now suppose that the pat protein can also re-toxify NAG back into
active herbicide, as discussed above. A dangerous feedback loop may
be created: We eat Liberty Link corn or soy. Our gut bacteria, plus
the pat protein, turns NAG into herbicide. With more herbicide, more
bacteria are killed. This increases the survival advantage for
bacteria that contain the pat gene. As a consequence, more bacteria
end up with the gene. Then, more pat protein is produced, which
converts more NAG into herbicide, which threatens more bacteria,
which creates more selection pressure, and so on. Since studies have
not been done to see if such a cycle is occurring, we can only
speculate.

Endocrine disruption at extremely low doses

Another potential danger from the glufosinate-tolerant crops is the
potential for endocrine disruption. Recent studies reveal that
endocrine-disrupting chemicals (EDCs) can have significant hormonal
effects at doses far below those previously thought to be
significant. The disruptive effects are often found only at minute
levels, which are measured in parts per trillion or in the low parts
per billion. This is seen, for example, in the way estrogen works in
women. When the brain encounters a mere 3 parts per trillion, it
shuts down production of key hormones. When estrogen concentration
reaches 10 parts per trillion, however, there is a hormone surge,
followed by ovulation.

Unfortunately, the regulation and testing of agricultural chemicals,
including herbicides, has lagged behind these findings of extremely
low dose effects. The determination of legally acceptable levels of
herbicide residues on food was based on a linear model, where the
effect of toxic chemicals was thought to be consistent and
proportional with its dosage. But as the paper 'Large Effects from
Small Exposures' shows, this model underestimates biological effects
of EDCs by as much as 10,000 fold.

In anticipation of their (not-yet-commercialized) Liberty Link rice,
Bayer CropScience successfully petitioned the EPA in 2003 to approve
maximum threshold levels of glufosinate ammonium on rice. During the
comment period preceding approval, a Sierra Club submittal stated the
following.

"We find EPA's statements on the potential of glufosinate to function
as an endocrine-disrupting substance in humans and animals as not
founded on logical information or peer-reviewed studies. In fact EPA
states that no special studies have been conducted to investigate the
potential of glufosinate ammonium to induce estrogenic or other
endocrine effects. . . . We feel it's totally premature for EPA at
this time to dismiss all concerns about glufosinate as an endocrine-
disrupting substance. . . . Due to the millions of Americans and
their children exposed to glufosinate and its metabolites, EPA needs
to conclusively determine if this herbicide has endocrine-disrupting
potential."

The EPA's response was that "glufosinate ammonium may be subjected to
additional screening and/or testing to better characterize effects
related to endocrine disruption" but this will only take place after
these protocols are developed. In the mean time, the agency approved
glufosinate ammonium residues on rice at 1 part per million.

Since glufosinate ammonium might have endocrine disrupting
properties, even small conversions of NAG to herbicide may carry
significant health risks for ourselves and our children.

The EPA's response was that "glufosinate ammonium may be subjected to
additional screening and/or testing to better characterize effects
related to endocrine disruption" but this will only take place after
these protocols are developed. In the mean time, the agency approved
glufosinate ammonium residues on rice at 1 part per million.

Since glufosinate ammonium might have endocrine disrupting
properties, even small conversions of NAG to herbicide may carry
significant health risks for ourselves and our children.

Inadequate animal feeding studies

If we look to animal feeding studies to find out if Liberty Link corn
creates health effects, we encounter what independent observers have
expressed for years-frustration. Industry-sponsored safety studies,
which are rarely published and often kept secret, are often described
as designed to avoid finding problems.

If we look to animal feeding studies to find out if Liberty Link corn
creates health effects, we encounter what independent observers have
expressed for years- frustration. Industry-sponsored safety studies,
which are rarely published and often kept secret, are often described
as designed to avoid finding problems.

In a 42-day feeding study on chickens, for example, 10 chickens (7%)
fed Liberty Link corn died compared to 5 chickens eating natural
corn. Even with the death rate doubled, "because the experimental
design was so flawed," said bio-physicist Mae-Wan Ho, "statistical
analysis failed to detect a significant difference between the two
groups." Similarly, although the GM-fed group gained less weight,
the study failed to recognize that as significant. According to
testimony by two experts in chicken feeding studies, the Liberty Link
corn study wouldn't identify something as significant unless there
had been "huge" changes. The experts said, "It may be worth noting,
in passing, that if one were seeking to show no effect, one of the
best methods to do this is would be to use insufficient replication,
a small n," which is exactly the case in the chicken study.

Without adequate tests and with a rubber stamp approval process, GM
crops like Liberty Link corn may already be creating significant hard-
to-detect health problems. In Europe, Japan, Korea, Russia, China,
India, Brazil and elsewhere, shoppers have the benefit of laws that
require foods with GM ingredients to be labeled. In the US, however,
consumers wishing to avoid them are forced to eliminate all products
containing soy and corn, as well as canola and cottonseed oils. Or
they can buy products that are organic or say "non-GMO" on the
package. Changing one's diet is a hassle, but with the hidden
surprises inside GM foods, it may be a prudent option for health-
conscious people, especially young children and pregnant women.



Jeffrey Smith is the author of the international bestseller, 'Seeds
of Deception.' The information in this article presents some of the
numerous health risks of GM foods that will be presented in his
forthcoming book, 'Genetic Roulette: The documented health risks of
genetically engineered foods,' due out in the fall.

---------------------------------------------------------------------
------- ----

Spilling the Beans is a monthly column available at
www.responsibletechnology.org.
---
Michel Dussandier - - - http://midier.net

Le marché est ennemi de la science,
car il ne connait que le court terme.