The dangers
which are posed by the tidal wave of biotechnological products are real. At
a meeting in Asilomar in 1975 a group of scientists drawn from the Committee
on Recombinant DNA of the US National Academy of Sciences, which included
the Nobel Prize winner, James Watson, warned about the dangers of genetic
engineering. They stated that "there is serious concern that some of
these artificially recombinant DNA molecules could prove biologically hazardous"
. This conference upheld the moratorium on recombinant DNA experiments. Jeremy
Rifkins acceptes that the reason for the moratorium had more to do with the
potential legal liabilities of creating bio-hazards than concern for the human
health of environmental risks of the new technology .
Almost 20 years later an international group of scientists meeting in Malaysia
in July 1994 called attention to the scientific flaws inherent in the genetic
engineering paradigm. The believe that genetic engineering is based on the
false premise that each individual feature of an organism is encoded in one
or more specific, stable genes and that the transfer of these genes results
in the transfer of these discrete features. The truth is that no gene works
in isolation but as part of an extremely complex genetic network. In fact
the function of each gene is dependent on the context of all the other genes
in the genome. The same gene, for example, will have very different effects
from individual to individual, because other genes are different.
The scientists who met in Malaysia pointed out that the development of any
trait results from many complex interactions between genes and their cellular
context and the external environment. There are numerous layers of feedback
mechanisms linking all these levels. These scientists insist that, in a significant
number of cases, it is impossible to predict the consequences of transferring
a gene from one type of organism to another. Furthermore, genetically engineered
organisms, especially micro-organisms, may migrate, mutate and be transferred
to other organisms and species. In some cases the stability of affected organisms
and ecosystems could be affected and threatened .
It is for this reason that Dr. Mae-Wan Ho a geneticist, argues that genetic
engineering is a crude and imprecise operations and consequently is inhertently
hazardous to health and biodiversity. The insertion of a foreign gene into
the host genome is a random process, not under the control of the genetic
engineer. It is through the use of artificial vectors that the horizontal
gene transfer is achieved. The transferred gene can give rise to random genetic
effects including cancer . She believes that the technology will contribute
to an increase in the frequency of horizontal transfer of those genes that
are responsible for virulence and antibiotic resistance, and allow them to
recombine to generate new pathogens .
Such fears are dismissed by other geneticists, but even if there is a remote
chance of this happening the whole genetic engineering enterprise should be
put on hold until independent scientific research has addressed these issue
over a considerable period of time.
Potential Risks to Humans and the Environment
Antibiotic Resistance
Production of New Toxins Diminished
nutritional quality
Creation of New, More Virulent Viruses
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Some of
the risks to human health and the environment include: the potential to cause
allergies; an increase in antibiotic resistance and toxicity; misleading the
consumer into thinking that the produce is fresh and, finally, unpredictable
gene expression in the engineered organism. A group of scientists in the United
States calling themselves the Council for Responsible Genetics have called
for a more proactive approach from the regulatory agency which is the Food
and Drug Administration (FDA) in monitoring and regulating genetically engineered
foods because of these risks.
Allergies
All allergies are caused by proteins. Genetic engineering involves adding
new proteins to altered products. The FDA warns that new proteins in foods
might cause allergic reactions in some people. Transgenic crops could bring
new allergens into foods that sensitive individuals would not be in a position
to avoid. It is possible for example to transfer the gene for one of the many
allergenic proteins found in milk into vegetables like carrots. People who
ought to avoid milk would not be aware that transgenic carrots contained milk
proteins.
The problem is unique to genetic engineering. Genetic engineering routinely
moves proteins into the food supply from organisms that have never been consumed
as food by human beings. Some of those proteins could be food allergens, since
virtually all known food allergens are proteins. Recent research substantiates
concerns about genetic engineering rendering previously safe foods allergenic.
A study by scientists at the University of Nebraska found that soybeans genetically
engineered to contain Brazil-nut proteins caused reactions in individuals
allergic to Brazil nuts. Blood serum from people known to be allergic to brazil
nuts was tested for the appropriate anti-body response to the gene transferred
to the soya bean. When seven out of nine volunteers responded to the genetically
engineered soybean the researchers concluded that the allergenicity had been
transferred with the transferred gene.
Scientists have a limited ability to predict whether a particular protein
will be a food allergen, if consumed by humans. The only sure way to determine
whether protein will be an allergen is through experience. Thus importing
proteins, particularly from non-food sources, is always a gamble from the
point of view of allergenicity. It is generally recognized that there has
been a significant rise in allergies, especially among children in recent
decades. With 8 percent of children showing allergic reactions to many commonly
eaten foods it seems foolish in the extreme to do anything that might increase
allergenicity. It is also worth bearing in mind that many of the genes being
transferred to the trangenetic food have never been part of the human diet
since the beginning of human evolution over two million years ago.
Antibiotic Resistance
Production of New Toxins Diminished
nutritional quality
Creation of New, More Virulent Viruses
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Genetic
engineering often uses genes for antibiotic resistance as "selectable
markers." Early in the engineering process, these markers help select
cells that have taken up the foreign genes. Although they have no further
use, the genes continue to be expressed in plant tissues. Most genetically
engineered plant foods carry fully functioning antibiotic resistant genes.
The most commonly used marker genes are the npt11 gene which confers resistance
to kanamycin, neomycin and geneticin and the bla gene which confers resistance
to ampicillin.
The presence of antibiotic resistant genes in foods could have two harmful
effects. First, eating these foods could reduce the effectiveness of antibiotics
which are taken with such a meal. Antibiotic resistance genes produce enzymes
that can degrade antibiotics. If a tomato with an antibiotic resistant gene
is eaten at the same time as an antibiotic, it could destroy the antibiotic
in the stomach.
Secondly, the resistant genes could be transferred to human or animal pathogens,
making them impervious to antibiotics. If transfer were to occur, it could
aggravate the already serious health problem of antibiotic-resistant disease
organisms. Although unmediated transfers of genetic material from plants to
bacteria is highly unlikely, even a slight risk of this happening requires
careful scrutiny in light of the seriousness of antibiotic resistance in the
population at large. The discovery by scientists at Cologne University in
1998 that DNA which had been fed to a mouse survived in the digestive system
and subsequently invaded other cells in the mouse's body should raise serious
questions and slowdown the entry of GE products into the food chain until
there is much more research on their ultimate impact on human health .
It is also true that the highly mosaic character of most vector constructs
makes them structurally unstable and prone to recombination. According to
scientists opposed to genetic engineering this may be why viral-resistant
transgenic plants generate recombinant viruses more readily than non-trangenetic
plants .
Antibiotic Resistance
Production of New Toxins Diminished
nutritional quality
Creation of New, More Virulent Viruses
Return to Top
Many organisms
have the ability to produce toxic substances. These substances help the organism
defend itself against many predators in their environment. In some cases,
plants contain inactive pathways leading to toxic substances. The addition
of new genetic material, through genetic engineering, could reactivate these
inactive pathways. Alternatively it could increase the levels of toxic substances
within the plants. This could happen, for example, if the on/off signals associated
with the introduced gene were located on the genome in places where they could
turn on the previously inactive genes. In the light of these considerations
many argue that genetically engineered foods pose new and unique challenges
in terms of food safety.
Concentration of Toxic Metals
Some of the new genes being added to crops can remove heavy metals like mercury
from the soil and concentrate them in the plant tissue. The purpose of creating
such crops is to make possible the use of municipal sludge as fertiliser.
Sludge contains useful plant nutrients, but often cannot be used as fertiliser
because it is contaminated with toxic heavy metals. The idea is to engineer
plants to remove and sequester those metals in inedible parts of plants. In
a tomato, for example, the metals would be concentrated in the roots; in potatoes
in the leaves. Turning on the genes in only some parts of the plants requires
the use of genetic on/off switches that turn on only in specific tissues,
like leaves.
Such products pose risks of contaminating foods with high levels of toxic
metals if the on/off switches are not completely turned off in edible tissues.
There are also environmental risks associated with the handling and disposal
of the metal-contaminated parts of plants after harvesting. This is a classic
example of a technological fix for an environmental problem that ought to
be addressed at its source. The way to guarantee that sewage sludge can be
used in agriculture is to ensure that toxic substances do not enter sewerage
plants in the first instance.
Most of the focus on health hazards associated with genetic engineering stem
from considering the genetic material that is added to organisms. There is
also the possibility that the removal of genes can cause problems. For example,
genetic engineering might be used to produce decaffeinated coffee beans by
deleting or turning off genes associated with the production of caffeine.
But caffeine helps protect coffee beans against fungi. Beans that are unable
to produce caffeine might be coated with fungi, which can produce toxins.
Fungal toxins, such as aflatoxin, are potent human toxins that can remain
active through processes of food preparation. Finally it is worth noting that
the FDA is concerned that toxins may be produced at unusually high levels
as a result of genetic engineering.
Diminished
nutritional quality
Antibiotic Resistance
Production of New Toxins Diminished
nutritional quality
Creation of New, More Virulent Viruses
Return to Top
A possible
consequence of genetically engineered foods is an alteration of the nutritional
content of the resulting product. The FDA cautions that nutritional value
could be significantly decreased without the crop exhibiting any outward signs.
Humans have come to rely on certain characteristics of fruits and vegetables
to indicate nutritional quality and flavour. For example, bright colour in
peppers, apples and other fruits is generally associated with taste and ripeness.
Genetic engineering may mislead consumers into buying fruits and vegetables
which appear to be fresh and just about ripe, but in fact are engineered to
last longer on the shelf and as a consequence may lack nutritional quality.
This would have serious implications for public health and needs to be taken
on board by monitoring and regulatory agencies.
Potential Future Problems
History has shown that it takes a few decades for the full set of risks associated
with any technology to be identified. In the 1920s no one predicted that CFCs
could cause such harm to the ozone layer. The ability to imagine what might
go wrong with genetic engineering is limited by the current knowledge in such
disciplines as physiology, genetics, and nutrition.
We should not forget too quickly how pressures from the food industry and
government agencies led to the failure of the UK authorities to link BSE with
a new variant of the incurable human condition CJD. Those who raised questions
about this connection in the mid-1980s were often criticised and even ridiculed
by their colleagues. Dr. Tim Holt, a Yorkshire doctor, told a UK government
enquiry into BSE how a pathologist at the Government's central veterinary
laboratory investigating mad cow disease said that the transmission to humans
was as "unlikely as a being struck by lightening" . Finally, whereas
with other technologies mistakes can be rectified by redesigning the machinery,
mistakes in the area of genetic engineering are much more difficult to correct.
The need for caution is highlighted by the controversy surrounding the production
of transgenetic pigs to provide organs for human transplant operations. Companies
on both sides of the Atlantic have engineered pigs to carry human protein
on the surface of their cells so that the organs will not be rejected by the
human immune system. At first glance this seems to be a brilliant way of meeting
the demand for organs for transplant operations. Unfortunately, researchers
have found that the pigs can carry at least two retroviruses. One of these
has the potential to infect human cells. Even though the US Food and Drug
Administration (FDA) have been provided with the results of the research they
have continued to allow the transplants to take place. One of the researchers
involved felt that the least the FDA should have done is ban the transplants
. Given the presence of these viruses many scientists would argue that pig
organs can never be a safe replacement for human lives .
Creation of New, More Virulent Viruses
Antibiotic Resistance Production
of New Toxins Diminished
nutritional quality
Creation of New, More Virulent Viruses
Return to Top
One of
the most common applications of genetic engineering is the production of virus-tolerant
crops. Such crops are produced by engineering components of viruses into the
plant genomes. For reasons not well understood, plants producing viral components
on their own are resistant to subsequent infection by those viruses. Such
plants, however, pose other risks of creating new or worse viruses through
recombination.
Recombination can occur between the plant-produced viral genes and closely
related genes of incoming viruses. Such recombination may produce viruses
that can infect a wider range of hosts or that may be more virulent than the
parent viruses.
In the late 1980s the National Institute of Allergy in the US sought an animal
model suitable for studying AIDs. Researchers introduced the AIDs virus into
mice. Critics of the experiment feared that if the AIDs infected mice escaped
this could create a new and even more deadly source of AIDs infection. Those
conducting the experiment dismissed such fear as unfounded and alarmist. A
study conducted by the Dr. Robert Gallo, one of the co-discoverers of the
AIDs virus, and subsequently published in the magazine Science, cautioned
against using animal research models. He and his colleagues argued that the
AIDs virus carried by the experimental mice might combine with other other
viruses that are carried by mice. This could result in the creation of a new
more virulent form of AIDs that could be transmitted in novel ways, even through
the air .
Copyright
2001 by Team C0123260
The Legenders , RJC, Singapore
