November 2012
A clarification on why animals fed GM are more likely to
drop dead in the lab than in the field.
***
In August 2012 we reported
that, during two livestock feeding trials of Syngenta's 'Bt176' GM
maize, in America and Germany, some of the cows sickened and died;
the illness was never identified (see DEAD COWS UNDER THE CARPET - August 2012).
These unexpected events during tests
haven't translated into widespread deaths in the field when animals
have been given feed containing Bt176 corn, or other GM crops with
the same artificial gene (cry1Ab).
It's been drawn to
our attention that our explanation of why the laboratory and field
studies could give such different results was too concise. So, in
the interests of clarity, here's a fuller description.
There's no information on the American study in which test-animals died, but the German cows were fed increasing rations of Bt176 until, by the 3rd year, they were getting only the GM corn in their feed. The problems started the following year, and got worse the year after. This suggests that consistent, prolonged feeding with a single GM crop, Bt176, may be linked to serious ill-health.
A typical
commercial herd will be fed on various feed formulations made from
whatever type, and in whatever proportions, of commodity corn happen
to have rolled off the production line. The animals will rarely be
given feed with completely identical ingredients for any length of
time, and four years in a row would be very rare indeed.
To
give some idea of the scale of the variety of corn strains which
could go into the mix, the European Commission has authorised
importation of twenty-seven
different GM maize varieties, containing one or more of eight
different Bt genes. Add to these, at least one strain containing a
'vip'
insecticide-producing gene, a multitude of herbicide-tolerant
versions, and the odd genetic marker (such as ampicillin resistance)
as a production aid.
Bt176
and eight other Bt corn varieties imported into the EU contain cry1Ab
genes. These eight other crops aren't directly related to Bt176: the
DNA constructs are different and they're inserted in different places
in the genome. Some of these might be safe, some might cause harm,
they all might be safe, they all might be harmful. But, if you feed
them to animals in varying quantities and varying combinations for
varying lengths of time, and mix them with unknown proportions of
eighteen other GM maize varieties plus the unknown proportions of
unknown conventional maize (Bt crops are supposed to planted with a
20% 'refuge' of non-GM maize), it's unlikely you'll see a single,
clear problem consistently enough to make a definite link to any one
GM maize type.
And, there's
another great unknown in GM animal feed: Bt176 (and possibly all GM
maize) seems to be unstable.
Bt176
corn is supposed to contain a DNA construct with two copies of
cry1Ab. In 2003,
molecular studies of several GM crops in the EU found that the
artificial DNA constructs had rearranged and in some cases altered
the host plant's DNA. The putative cry1Ab
gene in Bt 176 turns out to be more similar to cry1Ac.
Cry1Ac is not authorised for use
in Europe and the protein it generates has been identified as a
potent systemic and mucosal immunogen, as potent as cholera toxin.
It was also found that, whatever the Bt gene in Bt176 plants actually
is, it seems to have expended itself to 4-5 copies. Bt 11 maize,
which is still on the market and also contains a cry1Ab
gene, was found on molecular analysis to have incorporated extra
chunks of bacterial and maize DNA. Also, Bt11 seems to be
contaminated with Bt 176.
The length of time
it took for the German cows to sicken suggests some cumulative toxic
effects may be present in Bt176. If the animals have been fed on
ever-changing commodity corn, there would probably be little
opportunity for accumulation.
However,
the apparent harmful effects of Bt176 might not be directly due to
any toxic qualities in
the feed. Interference with the digestion or changes in gut
microflora due to prolonged exposure to this maize are strong
alternative candidates.
Besides providing a
novel substrate for pathogenic microbes to feed on, horizontal gene
transfer from Bt176 (especially in light of its instability) could
generate novel bugs which don't support health. Such effects are
less likely to become evident in herds fed on more varied
maize-types, where the pressure on the gut flora to change will not
be constant.
On the subject of
gut microbes or nutritional interference, there's plenty of scope for
undetected general weakening of the animals. While livestock aren't
kept alive long enough to suffer much chronic disease as humans will,
susceptibility to infection is a more likely symptom. Infections
will be routinely treated with antibiotics or vaccines, or by killing
any vectors identified: the connection with GM feed will not be made.
The trick to
'proving' safety is to create so much back-ground noise that any
ill-effects will be drowned out.
The
claim that GM food has been 'proven' safe because 300 million
Americans have been eating it for decades without evidence
of harm is as tenuous a proof of safety as the lack of deaths in
GM-fed cattle. Just think what all those American guinea-pigs are
actually eating: a vast variety of processed GM junk. Chronic
disease has been rising for years: who could possibly pin any blame
on GM food?
Back-ground noise
can cover up a huge groundswell of disease and death.
Note. Colorado
State University information on Bt176 corn tells us that it was
withdrawn in America in 2001 ostensibly because it afforded poor
protection against the European corn borer later in the season. This
was also the year that Syngenta got their second hint that the corn
killed cows.
SOURCES:
- Transgenic crops discontinued, Colorado State University, December 2004 http://cls.casa.colostate.edu/transgeniccrops/defunct.html
- Unstable Transgenic Lines Illegal, Institute of Science in Society Report, 3.12.03
- EU register of genetically modified food and feed, EU Register of authorised GMOs, European Commission DG Health and Consumers
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