Genetically Modified Foods: Its Uses, Environmental and Health Concerns- By Oghaghare Ese Freeman

Biotechnology, genetic modification, transgenic crops, are words and phrases being tossed around in the debate on genetically manipulated food, but what does this all mean? The language of genetic manipulation can be one of the greatest barriers to many persons understanding of the technology. For the purpose of this paper, genetic modification could simply be described as, “the manipulation of an organism’s genetic make-up in order to create or enhance desirable characteristics from the same or another species.

Although biotechnology and genetic modification (GM) commonly are used interchangeably, GM is a special set of technologies that alter the genetic makeup of organisms such as animals, plants, or microbes. 

Biotechnology, a more general term, refers to using organisms or their components, such as enzymes, to make products that include wine, cheese, beer, and yoghurt.

Combining genes from different organisms is known as recombinant DNA technology, and the resulting organism is said to be “genetically modified,” “genetically engineered,” or “transgenic.”

GM products include medicines and vaccines, foods and food ingredients, feeds, and fibers.

The unit of heredity is the gene, segment of DNA (deoxyribonucleic acid) that carries in its nucleotide sequence information for a specific biochemical or physiologic property.

 

Genetic information is stored as a sequence of bases in deoxyribonucleic acid (DNA). Most DNA molecules are double stranded with complementary bases (A-T; G-C) paired by hydrogen bonding in the center of the molecule.

The genome is the totality of genetic information in an organism. Almost all of the eukaryotic genome is carried on two or more linear chromosomes separated from the cytoplasm within the membrane of the nucleus.

Eukaryotic cells contain mitochondria and in some cases, chloroplasts. Within each of these organelles is a circular molecule of DNA that contains a few genes whose function relates to that particular organelle. Most genes associated with organelle function, however, are carried on eukaryotic chromosomes. Many yeasts contain an additional genetic element, an independently replicating 2-um circle containing about 6.3kbp of DNA. Such small circles of DNA termed plasmids are frequently encountered in the genetics of prokaryotes. The small size of plasmids renders them amenable to genetic manipulation and, after their alterations, may allow their introduction into cells. Therefore, plasmids are frequently called upon in genetic engineering.

Genes essential for bacterial growth are carried on the chromosome, and plasmids carry genes associated with specialized function. Many plasmids carry genes that mediate their transfer from one organism to another as well as other genes associated with acquisition or rearrangement of DNA.

A genetically engineered plant always starts with a single genetically engineered plant cell. Genes are introduced into plant cells in tissue culture and these modified cells are then grown up into a plant. This will carry the ‘foreign’ gene in its cell, and can also pass it on to its offspring in its cell.

Having set-out a clear definition of the subject matter, its important I don’t bore readers with the biochemistry of the gene organization, transfer of DNA and the mechanisms involved in Gene Recombination and Gene Transfer. It would be nice I run through some history on the subject matter – GENETICALLY MODIFIED FOODS.

The history of genetically modified food can be traced back to the mid 19^th century, when Gregor Mendel- an Austrian monk and botanist, carried out an experiment where he crossbred tall pea species with short pea species to show that certain traits in one species were inherited by other in this process. Even though Mendel is considered to be the founder of science of genetics today, his efforts were not acknowledged until 20^th century. Mendel’s observations paved way for the development of first genetically modified plant- an antibiotic resistant tobacco plant, in 1983.

  
While genetic manipulation of foods can be traced throughout history, the modern marvels of GMOs and transgenic plants have come to light in just the last few decades. The 1980’s marked the scientific discovery that specific pieces of DNA could be transferred from one organism to another. This became the basis of the genetic modification process. In 1983, the first transgenic plant, a tobacco plant resistant to antibiotics was created.

After the breakthrough, it took the scientists another ten years to grow the first genetically modified food for commercial use. This transgenic crop was a tomato created by a California based company – Calgene. The new species of tomato - which was named Flavrsavr by the company, was made available commercially in 1994. It was genetically modified in such a manner that its shelf-life increased i.e it took longer for this variety of tomato to decompose after picked as compared to a normal tomato.

Even though consumers showed keen interest in the same, the company stopped its production in 1997 owing to the fact that its characteristic shelf-life made it less profitable for the company.

Some sources also cite that the actual reason for stopping the production of this crop was the competition it had to face from its conventional counterpart as well as some production problems that the company was subjected to.  

A European company manufactured a tomato paste from a genetically modified tomato species and made it available in the market in 1996.the controversies surrounding genetically modified food began with some scientists claiming that these genetically modified products were harmful for animals and human alike. One such scientist was Arpad Pusztai- a Hungarian-born biochemist and nutritionist, who revealed that he observed some harmful effects of these foods on the stomach lining and immune system of rats that he fed genetically modified potatoes in 1998. Five years later, Monsanto the leading biotechnology company, introduced herbicide-immune soybeans otherwise known as “Round-Up-Ready”.

Today, biotechnology and the process of genetic modification is emerging and advancing throughout the planet. As of 2004, genetically modified crops were being grown by 8.25million farmers in 17 countries. 

Commercially, four genetically modified crops dominate global biotechnology agriculture with soybeans accounting for 60% of GM crop area, maize accounting for 23% of GM crop area, cotton accounting for 11% of GM crop area, and canola accounting for 6% of GM crop area. The United States is among the leading proponents for the advancement of biotechnology. In terms of global land area planted in varieties of engineered crops, the United States far surpasses global competition accounting for 59% of all GM crop. In terms of actual land area, the United States utilizes 47.6 million hectares for biotech agriculture as of 2004. 

Perhaps the best illustration of the extent to which the United States dominates this technology can be found through comparisons with other countries. Again in terms of percentage of land area planted in biotech varieties as of 2004, the nation of Argentina comes in a distant second to the United States accounting for 20% or 16.2 million hectares of GM crop agriculture.

Some Applications of genetic modification are hereby highlighted below:

WEED CONTROL

Weeds control is the current commercial terminology for using genetic engineering to make crops resistant to herbicides, allowing farmers to spray growing crops to kill weeds but not their crops.

An alternative to engineering in herbicide tolerance would be to engineer plants to contain natural weed killers (Little is known about mechanisms involved).

Meanwhile, Monsanto, which among other agrochemical companies has developed herbicide tolerance genes, claims that its commercial strategy is to gain market share for its herbicides, and not to increase the overall use of herbicides, popularly held. Sensitive to the fears and criticisms from the environmental movement, Monsanto Scientists claim that their research has concentrated on herbicides which needs to be applied only in small amounts, have a low toxicity, degrade quickly, and stick to the soil rather than washing easily into streams or groundwater.

However, herbicides use may well increase because farmers will be able to spray them more liberally and often, without fear of damaging their crops. Exactly how much they spray will depend on farm economics, such as the cost of the herbicides and engineered crops, the wages saved through reduced weeding and price for which farmers can sell any increased yield.

INSECTS CONTROL

Insect resistance has already been achieved in tomatoes, tobacco and cotton by the transfer of genes from a common soil bacterium (Bacillus thuringiensis or Bt ). The genes direct the production of protein toxins, or poisons, that kill certain insects.

Tomatoes with Bt genes where completely protected from attack of caterpillars that stripped other unprotected plants in the same field down to their stalks, scientists reported in a Monsanto experiment. Tobacco has also been successfully protected from the tobacco hornworms with a Bt gene.

Such plants should offer the farmer many advantages;

(a.)  Labour-free insect protection in every season, from seedling to maturity;

( b.) Protection of every part of the plant, even parts difficult to reach with sprays.

(c.)  Protection from crop-eating insects without damaging beneficial insects; and confinement of the pesticide to the plant, so leaving soil and ground water unaffected.

Different Bt toxin genes are lethal to different insects. So in principles, a Bt gene can be selected to kill a particular pest, but leave beneficial insects alone. But although many different toxins genes and the corresponding proteins have been isolated, often scientists have no knowledge of what insects they infect.

Although the Bt proteins are highly toxic to insects, they are claimed to be harmless to people and animals; which digest them like any protein.

Rice may also be given Bt protection. Plant genetic Systems, a private university-linked Biotechnology research company in Ghent, Belgium, with an access has linked up with insect scientist at the International 
Rice Research Institute in Manila. This collaboration aims to transfer Bt genes into rice to kill rice pests. The target pests are stem borers, leaf borers and caseworms.

However, the Ghent scientists say that ‘there is evidence that insects can evolve around these toxins. So they should only be added to varieties already selected to be resistant by ordinary breeding.

There are other applications of genetic modification which includes Maintenance of plants health, Blocking of other genes, Improvement of crop quality, Production of special chemicals and so on.

The importance and novelty of genetically modified foods cannot be overemphasized; It however comes with some fears and concerns most especially its associated environmental and health concerns.

In one sense, genetic engineering is only an amplification of what farmers have long done- to shuffle genes through breeding to create useful plants and animals, or to move a useful plant or animal from one continent to another.

But some groups, oppose most, if not all, aspects of biotechnology. They do so partly on the moral ground that it represents an unwarranted and unnatural tampering with the genetic make-up of living things, tending to reduce animal and plant life to the status of commodities for human consumption. They contend that there are many ways in which biological systems can benefit us without tampering with the genetic code, and that we need to develop ways of working with nature rather than controlling it if we are to avoid threatening the viability of the planet.

Other scientists, especially ecologists, as well  as environmentalists, while not condemning biotechnology and genetic engineering out of hand, urge extreme caution, especially over the release of novel organisms into the environment.

The ecological Risks of Engineered Crops, genetically modified crops pose six kinds of potentials risks;

(a.)  First, the engineered crops themselves could become weeds, a broad term that covers plants with undesirable effects.

(b.) Second, the crops might serve as conduits through which new genes move to wild plants, which could then become weeds.

(c.)  Third, crops engineered to produce viruses could facilitate the creation of new, more virulent or more widely spread viruses.

(d.) Fourth, plants engineered to express potentially toxic substances could present risks to other organisms like birds or deer.

(  (e.)  Fifth, crops may initiate a perturbation that may have effects that ripple through an ecosystem in ways that are difficult to predict

Finally, the crops might threaten centers of crop diversity.

Although no major human health problems have emerged in connection with genetically modified food crops, which have been consumed by significant numbers of consumers. As with environmental effects, only dramatic effects easily connected to engineered foods would likely have been detected. Because genetically modified are not labeled, people suffering ill effects would have difficulty relating them to consumption of such products.

Over the past decade, food safety experts have identified several potential problems that might arise as a result of engineering food crops, including the possibilities of introducing new toxins or allergens into previously safe foods, increasing toxins to dangerous levels in foods that typically produce harmless amounts, or diminishing a food’s nutritional value. Problems like these would have to occur at very high levels within the US population to attract the attention of regulators.

Among these potential impacts, scientists and regulators have been most worried about new allergens, and indeed, two events within the last decade legitimate that concern. First, paper published in the New England Journal of Medicine (NEJM) in 1996 confirmed predictions that genetic engineering could transfer an allergen from a known allergenic food to another food. A few years earlier, scientists are pioneer Hi-Bred seed company had successfully transferred a gene from Brazil nut soybean to improve the gain from Brazil nut into soybean to improve the grain crop’s nutritional quality. Subsequent experiments showed that people allergic to Brazil nuts were similarly allergic to the transgenic soybean.

In assessing the risks and benefits of GM foods it is important to make a list of risks and benefits which provides a framework that makes it easier to screen for the possible combinations of technology, crop, and ecological context that are likely to be relatively benign or hazardous. However, constructing such lists is only the first step in a risk assessment. These risks need to be quantitatively assessed for specific organisms in different contexts on a case-by-case basis.

It is recommended by ecologist for an incremental, tiered approach to risk assessment that moves from the laboratory to greenhouse and field trials and finally to gradually increased monitored use.

While field trials are a necessary step in evaluating GM crops, on their own they are insufficient. A more comprehensive analysis is required that includes an assessment of the relative benefits and risks of GM crops for other ecosystems and for people.

 

The constellation of paradoxes surrounding genetically modified foods should not, of course blind us to the fact that potential hazards may accompany this technology, like any other. One obvious possibility is the transfer of genes from genetically modified crops to non-modified crops, where they may have foreseen consequences.

Due to uncertainties in the risks and benefits of genetically modified foods on consumption by humans, the following recommendations are proposed in the report, “Recombinant DNA safety considerations”, published by the Organization for Economic Co-operation and development. It proposes that;

•  An independent review of the potential risks of any proposed release should be conducted, prior to release.

• The development of engineered organisms for release should move “step-wise” from laboratory, to growth chamber, to limited field testing and finally to a large-scale field testing and finally to large-scale field testing.

•   Risks research should be encouraged.

•   Meanwhile, the considerable existing data on the health and environmental effects of non-engineered organisms should be used to guide assessments of the effects of the release of engineered organisms.
  
  
  This piece was written in response to some experts and technocrats who are calling on the National Assembly to sign into law a bill on GM foods on the table before them. I want to urge the National Assembly to bring to the fur a holistic approach by having a public interactive session with Scientists, Environmentalists, Multinational Food industries and the general public, where all would have their interest taken into consideration.
  
  
  (An excerpt from a seminar presented by – Oghaghare Freeman Ese.)