Genetically Engineered Food: Panacea or
Pandora's Box?
Thanks to the Society for the Promotion of Nutritional Therapy, for the
reproduction of the following article.
Michael Antoniou, MA (Oxon.), PhD
Graduated from Oxford in biochemistry, 1977. Obtained a PhD in molecular
biology from the University of Reading, 1980. Research in basic molecular
biology for the past 16 years with expertise in genetic control mechanisms.
Currently senior lecturer in molecular pathology and head a research group
at one of London's leading teaching hospitals. A major objective is to
contribute to the development of safe and efficacious applications of genetic
engineering within a clinical context ("somatic gene therapy").
Genetic engineering has already made a significant impact in the manufacture
of foods and food supplements. Enzymes derived from genetically engineered
bacteria, yeast or fungi are now routinely used to increase efficiency
in a number of processes. Pectin degrading enzymes increase both the yield
and the clarity of tinned fruit and fruit juices. Amylases are used in
bread making to ensure better rising of the dough. Rennet which is used
in the production of cheese was traditionally obtained from the calf stomach.
Nowadays virtually all cheese is made from rennet derived from yeast or
bacteria engineered to produce this calf enzyme more cheaply and in essentially
limitless quantities. Earlier this year in the UK, approval was granted
for the manufacture and marketing of riboflavin from genetically engineered
bacteria.
The list of agricultural applications of this technology are even more
extensive and impressive and will therefore be the main focus of this article.
Genetic engineering is said to promise among other things, disease resistant
crops and animals, tastier food with improved nutritional value, crops
that produce their own pesticide and which are herbicide resistant and
crops which can grow in "marginal" soil and climatic conditions
with higher yields to feed the world's ever expanding population. Arguably
the greatest claim of those who endorse the use of genetic engineering
in agriculture, is that it is safe, more precise and a natural extension
of traditional cross breeding methods for generating novel varieties of
crops and farm animals. It is said that this new technology simply gives
nature a helping hand with something that would happen anyway. There is
no doubting the power of genetic engineering to produce more rapidly new
varieties of crops and farm animals. However, since technically speaking
traditional methods and genetic engineering bear little resemblance to
each other, how valid are these claims? Is it as precise and safe as it
is made out to be? If there are inherent dangers with this technology,
should we be using it in industrial processes and agriculture since there
are safer alternatives to producing the same products as well as new varieties
of crops and animals?
GENETICS and GENETIC ENGINEERING
In order to answer these questions we need to be familiar with some of
the basic principles of genetics and genetic engineering. Genes are discrete
units of DNA. They are the blueprints which carry the information
for the proteins which in turn make up all the structures and functions
(biochemistry) that constitute the body of any organism from bacteria to
humans. Gene function is extremely tightly controlled so that the right
proteins are made in the correct place within the organism, at the right
time in it's life and in the appropriate quantity. This ensures an integrated
and balanced functioning of all the tens of thousands of structures and
processes that make up the body of any complex organism be it plant or
animal. One will not normally find liver functions in the brain or leaf
specific proteins in the fruit and vice versa! Nature has also evolved
mechanisms whereby cross breeding can only take place between very closely
related species. With traditional breeding methods, different variations
of the same genes in their natural context are exchanged. This preserves
tight genetic control and functions that are vital for health and the integrity
of life as a whole.
In marked contrast genetic engineering allows the isolation, cutting, joining
and transfer of single or multiple genes between totally unrelated organisms
circumventing natural species barriers. As a result combinations of genes
are produced that would never occur naturally. Geneticallyengineered ("transgenic")
crops containing genes from viruses, bacteria, animals as well as from
unrelated plants have been generated. Furthermore, the newly introduced
gene units are composed of artificial combinations of genetic material.
For example, transgenic tomatoes and strawberries are under development
which contain the "anti-freeze" gene from an arctic fish. In
addition, parts of a plant virus are used to allow this fish gene to "switch
on" in it's new host. All this in turn coupled to an antibiotic resistance
"marker" gene. It is hoped this combination will allow greater
tolerance to frost. This is clearly a great technological advance. However,
the manipulation and transfer of DNA from one organism to another by genetic
engineering can only be carried out with any degree of precision in lower
forms of life such as bacteria and yeast although, as we shall see, complications
may arise even in these cases. The generation of transgenic plants and
animals is currently an imperfect technique. Once injected into the reproductive
cells of an organism, the introduced gene randomly incorporates itself
into the DNA of it's new plant or animal host. This always results in a
disruption, to a lesser degree, of the tight genetic control and balanced
functioning which is retained through conventional cross breeding. In addition,
it is assumed that the introduced gene will behave in exactly the same
way in it's new host as it does in it's native environment which frequently
will not be the case. These effects combine to always produce a totally
unpredictable disturbance in host genetic function as well as in that of
the introduced gene. Therefore from the standpoint of the fundamental principles
of genetics and the limitations in the technology, genetic engineering
is neither more precise nor a natural extension of traditional cross breeding
methods. If anything the opposite would appear to be true.
POTENTIAL HEALTH HAZARDS
Does the molecular imprecision of genetic engineering matter if quality
of life can be improved without safety or value of the food being compromised?
Unfortunately, disruptions in the biochemistry of the transgenic organism
have already been observed to produce a number of unexpected outcomes whose
unpredictably is the greatest worry. A tomato, for example has been engineered
to have a longer shelf-life but unexpectedly also bruises more easily which
resulted in major problems during it's harvesting. Furthermore, this tomato
may still look good after 6-8 weeks but is lacking in flavour and has reduced
nutritional value. Will the outcome be the same with the many other ripen-on-demand
or longer-shelf-life fruits and vegetables about to be launched?
The production of novel toxins and allergens poses the most immediate potential
health risk. In 1989 an epidemic of a new disease hit the USA. Called eosinophilia
myalgia syndrome (EMS) it was eventually traced after several months to
the consumption of a particular brand of tryptophan food supplement derived
from bacteria genetically engineered to overproduce this amino acid. The
engineering process had unexpectedly produced metabolic perturbations
resulting in the formation of a novel toxin from the excessive amounts
of tryptophan present within this organism and which contaminated the final
product. Out of the estimated 5000 people who contracted EMS, 37 died and
1500 are permanently disabled with sickness. Therefore, even in simple
cases such as bacteria where genetically engineered modifications can be
carried out with some precision, unpredictable disturbances in biochemical
functioning with disastrous outcomes can occur. It is therefore not surprising
to find that unexpected toxins and ill effects to the host have now been
documented in the more complex genetically engineered organisms such as
yeast, plants and animals. The only other recorded case of ill health in
humans resulting from a genetically engineered food is from soya containing
a brazil nut protein which, during pre-marketing tests, still gave rise
to reactions in individuals allergic to brazil nuts. Although overt health
problems are potentially rare, it is their unpredictably which causes
the greatest concern. Therefore, the lessons learnt from these incidents
serve as a timely reminder as hundreds of foods derived from genetically
engineered crops or produced using genetically engineered components
are poised for commercialism over the next few years. Generally, these
findings highlight the fact that there are always potential hidden dangers
when artificially manipulating on this finest level of life.
ENVIRONMENTAL IMPACT and BIODIVERSITY
The long term environmental impact of transgenic crops and animals is still
far from clear. Transgenic salmon containing genes from the arctic sea
flounder which grow six times larger and ten times faster are currently
being farmed in Canada and Scotland. Since 20% losses during storms is
the accepted norm on fish farms, this "super salmon" will inevitably
escape into the wild with unknown ecological consequences. The potential
problems with engineered micro-organisms and plants are even greater. There
are a number of ways in which genetically engineered modifications can
inadvertently be spread in the environment. Firstly transgenic crops can
simply cross pollinate with related wild varieties. Secondly many species
of micro-organisms are naturally adapted to pick up on new genetic material
through a number of different mechanisms which can result in the
very rapid spread of engineered traits including antibiotic resistance.
Plant viruses have also been demonstrated to readily incorporate into their
own genetic make up engineered genes in transgenic plants. This can not
only result in the rapid spread of engineered properties to other plants
but also the creation of new strains of disease causing viruses with an
altered host range. It is therefore particularly disconcerting to find
that an engineered insect virus possessing the scorpion toxin gene is currently
under trials in Canada for spraying on crops as a broad spectrum pesticide.
Most transgenic crops that have been produced or are under development,
are engineered to be resistant to herbicides or to generate their own pesticide.
Field trials in Scotland and Denmark using transgenic, herbicide resistant
oilseed rape, have already demonstrated efficient cross pollination with
related, normally weedy wild brassica varieties within a single growing
season generating herbicide resistant "superweeds". Similar findings
have been recorded with potatoes. Transgenic cotton containing the Bt bacterial
pesticide gene grown in the southern USA this year, still resulted in millions
of dollars in losses to the farmers from bollworms. Experiments have shown
that the continued presence of a pesticide on plants, as is the case with
genetically engineered varieties, results in the more rapid appearance
and maintenance of highly tolerant pests which may even have contributed
to the cotton disaster. A number of crops are also being generated for
growth characteristics such as wheat that can fix it's own nitrogen and
therefore require less artificial fertiliser, or rice that can grow in
marginal salty waters. The spreading of these properties to relatives through
cross pollination can result in immeasurable ecological disturbances as
wild plants are displaced by these more hardy varieties possessing engineered
traits. Transgenic crops would therefore appear to have a built in obsolescence.
They may lead to reduced use of herbicides, pesticides and artificial fertilisers
in the short term but an even greater dependence on agrochemicals in the
longer term as resistant weeds and insects rapidly appear in addition to
other ecological disturbances. This clearly results in higher costs to
the farmer and consumer as well as an increase in environmental pollution.
The use of genetic engineering threatens to compound an already existing
problem, namely the reduction in biodiversity of food crops. The global
dissemination of select hybrids for cereals and pulses produced by seed
companies in the more industrially developed nations of the world, has
already replaced most traditional varieties. Earlier this century there
were more than 100 000 varieties of rice grown in the world, each one ideally
adapted to the local conditions where it was propagated. The "green
revolution" has now reduced this to only 10-15 000 varieties. In addition,
a recent report by the National Research Council (NRC, Washington DC, USA)
focused on how indigenous crops in Africa such as fonio, pearl millet and
African rice have been discarded as inferior in favour of Asian rice and
European and American imports of maize and wheat. The wide scale introduction
of a few genetically engineered types will reduce this crop biodiversity
still further. This could have catastrophic consequences on world food
supply if, for example, an engineered pest resistant crop was to be destroyed
by the rapid appearance of tolerant insects. It was a lack of crop diversity
that resulted in the Irish potato famine 150 years ago! Furthermore, it
turns out that the indigenous African grains are far from inferior and
are not only nutritious but also well adapted to the harsher growing conditions
experienced in many parts of this continent. It would therefore appear
to be far more sensible to adopt the NRC's suggestion of developing these
natural varieties to feed Africa's burgeoning population rather than waste
effort producing genetically engineered wheat, maize or rice to withstand
climatic and geographical conditions which they cannot tolerate.
CURRENT SAFETY REGULATIONS: GENERAL TOXICITY TESTING REQUIRED
There are three advisory committees established by the government and which
are responsible for assessing the risks to health and the environment of
genetically engineered organisms (GMOs) and food products in general. All
three report to the Department of the Environment and the Ministry of Agriculture
Fisheries and Food. The release of GMO's be it bacteria, viruses, plants
or animals must be approved by the Advisory Committee on Releases to the
Environment (ACRE) who must be satisfied that no great danger is posed
by it's release. The safety of genetically engineered food and food products
produced using genetically engineered components and processes, is assessed
by the Advisory Committee on Novel Foods and Processes (ACNFP). If a product
receives safety clearance by the ACNFP, it is then referred to the Food
Advisory Committee which makes recommendations on matters regarding the
labelling, composition and chemical safety of these food products.
With regards to health risks, the ACNFP demands a very strict assessment
of the levels of known toxins and allergens. Unfortunately, there is no
requirement for general toxicity testing akin to that used for pharmaceuticals.
This may lead to unexpected, unknown toxins or novel allergens only being
discovered if a health problem arises. Furthermore, food processing which
either destroys or removes the genetic material and it's protein product
is assumed as being safe. Nevertheless, toxins and allergens may be present
in the final product. Interestingly, the tryptophan food supplement disaster
already discussed would occur even under these current rulings due to the
fact that it was caused by an unexpected, new toxic contaminant present
in the final, presumed pure product devoid of DNA and proteinaceous material.
It therefore would require neither toxicity testing nor, as we shall see,
labelling.
FULL DISCLOSURE LABELLING REQUIRED
At present, only products which are, or contain "live" GMOs (e.g.
salad vegetables, fruits, yoghurt), those deemed to be nutritionally "substantially
different" from the parental non-engineered organism and those which
contain genetic material from human or animal sources which may be objectionable
on religious or ethical grounds, need be labelled. Genetically engineered
modifications for "enhanced agricultural performance" (e.g. herbicide
and pest resistance), and processed food products derived from GMOs (e.g.
oil from soya beans or oilseed rape), those which have used GMOs a part
of their production (e.g. yeast in bread baking) or use products derived
from GMOs (e.g. enzymes from bacteria in fruit juice production; calf rennet
from yeast in cheese making, need not be labelled. Food processing which
destroys or removes the genetic material and the proteins derived from
it is assumed to be safe and does not require labelling.
Fortunately for those who have reservations about engineered food, earlier
this year the Codex Alimentarius Committee on Food Labelling which sets
international standards, ruled that genetically engineered food could not
be labelled as "organic" even if grown under organic husbandry
conditions.
It is clear that under this current UK and soon to be introduced EU legislation,
very few genetically engineered foods are required to be labelled. In the
vast majority of cases it is being left to food producers and retailers
as to whether a product should be labelled or not. Most major retailers
have stated that they will label all such products although some discrepancies
have already emerged. Only the Co-op supermarket outlet labels it's cheese
as being derived from genetically engineered rennet. No tinned fruit or
fruit juice is labelled as using enzymes from engineered micro-organisms
as part of it's manufacture.
The greatest concern is that the producers of commodity products such as
cereals, grain, pulses and oilseed rape are not in favour of labelling
and therefore not prepared to segregate engineered from natural varieties.
This in turn makes it very difficult for food processors and retailers
to know what is or is not engineered and to know what to label accordingly.
This includes the engineered herbicide resistant soya beans and pest resistantmaize
harvested this autumn in the USA and the herbicide/pest resistant oilseed
rape in Europe. Products from these crops are extensively used in the food
processing industry. Soya bean ingredients (flour, protein, oil, lecithin)
are added to 60% of all processed foods whereas components derived from
maize (flour, starch, corn syrup) are included in approx. 50% of processed
foods. Rape seed oil is inexpensive and widely used. Therefore, unless
legislation is passed to ensure segregation, it will be virtually impossible
to avoid genetically engineered components in our food even in the very
near future. Arguments concerning the impracticality of segregation are
untenable in the face of public announcements by wholesalers
and exporters in the USA that they are quite happy to provide segregated
soya beans if there was sufficient demand. In addition, simple and extremely
sensitive tests are being offered by a US company to check batches of grain
and pulses for the presence of genetically engineered varieties.
A full disclosure labelling of genetically engineered food is required
for two reasons. Firstly, labelling will protect the consumer's democratic
right to know what they are eating and allow them to make an informed choice
as to whether to buy these products. Secondly, without labelling it would
be difficult if not almost impossible to trace any health problems that
may arise given the diversity of people's diets. The source of the contaminated
tryptophan which caused the EMS tragedy took several months to trace since
the product was not labelled as being derived from a genetically engineered
bacterium. Also, even the presence of small amounts of an allergen in a
food product can cause a severe reaction in a sensitive individual who
clearly needs to avoid it.
CONCLUSIONS AND FUTURE DEVELOPMENTS
Generating new crop hybrids for higher yields has been the dominating factor
in modern agriculture for many years. However, quantity has been in many
cases at the expense of quality. High yielding varieties can not only be
deficient in flavour but also in nutritional value. It is perhaps ironic
that food producers are now relying on genetic engineering to put
the "taste" back into food rather than returning to more traditional
varieties.
When analysed from the viewpoint of the fundamental principles of molecular
genetics, it is evident that the generation of genetically engineered plants
and animals is an imprecise technology with inherent potential dangers.
Foods derived using this technology can therefore quite justifiably still
be called "experimental" especially in the absence of data testing
for the unexpected production of novel toxins and allergens. Clearly, biotechnologists
should not forget the basic principles of genetic functioning or the limitations
of the technology as it stands whilst trying to meet their technical and
commercial objectives. There is sufficient evidence to show that things
can still go drastically wrong. Furthermore in the absence of full mandatory
labelling of engineered foods, the public would appear to unwittingly be
participating in a vast global food experiment whose outcomes are far from
certain.
Although very few genetically engineered crops are currently approved or
already marketed, if current trends go unabated within the next 5-8 years
most food plants of the world will be modified by this technology. This
includes not only major commodity items (cereals and pulses) but also common
fruits and vegetables including apples, strawberries, cantaloupe melons,
grapes, sugar beet and potatoes to name but a few.
Those who do not want to participate, at least for the time being , in
the "experiment", will find it increasingly difficult to avoid
engineered foods. Given the ruling of the Codex committee, eating only
organically grown food would appear to be the easiest way of avoiding them.
The engineered soya beans and maize are due to arrive in Europe from the
USA this November [they are of course already here as this was written
last year] and will find their way, as discussed, into 60% of processed
foods. A boycotting of these processed foods, unless reassurances can be
given about the origin or variety of their soya and/or maize, would appear
to be the only course of action open to the concerned individual.
Last but not least we must also remember that unlike chemical pollutants
and other problems in the food chain such as a BSE epidemic, once genetic
pollution causing toxins/allergens and ecological disturbances is in our
soil, crops, animals and their wild relatives, it cannot be cleaned up
or simply allowed to decay and will be passed on to all future generations
indefinitely. Given that we have viable and safer alternatives is it worth
taking the risk?
POTENTIAL DANGERS OF GENETICALLY ENGINEERED FOOD
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Thanks to the Society for the Promotion of Nutritional Therapy, for the
reproduction of the following article.