What's wrong with GMOs?
What is genetic modification?
Genes consist of DNA which occurs in each cell of the plant or animal and organizes the production of protein. The DNA is modified naturally in sexual reproduction and has been artificially controlled by man over the centuries through selective breeding. It also occurs through external influences such as radiation, viruses or faults in replication, and reveals itself in changes in the proteins occurring in the organism.
Why do it artificially?
Artificial gene manipulation is quicker and more reliable than any of the above. Work is being done to modify plants for a number of reasons, including:
- To improve crop yields
- To develop crops that make more effective use of soil fertility
- To improve keeping properties, e.g. tomato puree
- To reduce post-harvest losses from pest, disease and fungal attack
- To improve the nutritional value of crops
- To make drought-resistant plants
- To produce saline tolerant plants
- To improve tolerance of plants to heat or cold
- To produce plants with in-built pest resistance
- To produce herbicide resistant plants
- To reduce allergic effects, e.g. low-allergy GM rice in Japan
- To develop alternative resources for such things as starches, fuels, plastics and medicines.
Synthetic rennet used in cheese manufacture and insulin are produced by genetically modified organisms.
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What are the dangers of GM food?
As changes in DNA affect the production of protein, provided the new protein is safe to eat, there is no problem. The modified DNA cannot affect the consumer, only the protein it produces in the plant or animal. Once this is properly investigated and passed as safe by the UK Advisory Committee on Novel Foods and Processes, we can be confident there is no other danger.
So far, tomato paste, maize and soya have been approved. Modified material is used for the production of rennet to make some ("vegetarian") cheeses but it is not present in the cheese itself.
What about the potato fed rats?
Some plants have a natural resistance to pests because they contain proteins called lectins. Some of these are poisons found naturally in some kinds of bean. Of the potatoes fed to the rats, some had been modified to produce lectins and others were injected with snowdrop lectin. It was these poisons that damaged the animals.
There were differences between the two sets of results but it is important to note that the two types of potato did not satisfy the "substantial equivalence" test which is applied to any GM food before it is approved for human consumption.
Dr Pusztai's methods and conclusions have since been discredited by the Royal Society.
By the way, the level of alkaloids found in conventional potatoes would make them unacceptable under present regulations. If Sir Walter were to try to introduce them into our diet today, they would not be permitted!
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What about effects on the environment?
Indiscriminate use of weedkillers is having a damaging effect on biodiversity. Tests so far suggest that GM crops need less herbicide for weed control. Glyfossate and glufossinate herbicides are used with gm crops are bred to be ubaffectedby them. These are biodegradable alternatives to the persistent weedkillers which are used with conventional crops.
The european corn borer is currently controlled by the application of indiscriminate pesticides which would not be necessary with crops incorporating the Bt modified gene.
Escapes of pollen from modified plants would only create the possibility of extending the range of plants with resistance to disease, pests or herbicides. Spread to other kinds of plant could only happen if they were botanically similar plants with which it could hybridize. There are none of these in the case of maize and GM potatoes grown in the UK. (See below)
What about the Monarch Butterflies?
There are many plants occurring naturally that already have inbuilt resistance to pests, fungal attack and herbicide, and they have not become "superweeds." There are already superweeds with conventional pedigrees growing in the UK, e.g. Japanese knotweed.
We should make sure that plants modified to resist pests are not harmful to beneficial insect life, including the pests' natural predators.
It is worth noting that the Monarch butterfly caterpillars killed in the laboratory experiments were deliberately treated with pollen from plants modified to resist attacks by pests. Conventionally bred plants, in this case maize, are regularly spayed with wide spectrum insecticides that kill all insect life indiscriminately, including any Monarch butterfly caterpillars that happen to get in the way.
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[Concern has been that eradication of weeds will have an adverse effect on the wildlife that depends on them.]
Later News
Golden Rice has been genetically modified to contain carotinoids, precursors of vitamin A, which is lacking in diets of the poor in countries where rice is a staple diet. The inventors, plant scientist Ingo Potrykus and biochemist Peter Beyer, have given up their rights and commercial firms have waived their licence fees, so that subsistence farmers in any developing country will eventually be able to cultivate Golden Rice varieties licence-free.
[Nature 01.02.01
"Superweed" Fears Groundless
There has been concern that GM plants could persist in the wild in the event of dispersal from their cultivated habitat. A long-term study has been carried out into the performance of transgenic crops in natural habitats. Four different crops (oilseed rape, potato, maize and sugar beet) were grown in 12 different habitats and monitored over a period of 10 years. In no case were the genetically modified plants found to be more invasive or more persistent than their conventional counterparts.
[Nature 08.02.01
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"But People Don't Want Them"
The fact is that the Greens have run a very successful campaign, based on emotion, not logic. The idea of Frankenstein foods has taken popular imagination and closed minds to potential benefits.
Africans refused to grow gm cereals becausse this woukd reduce their abikity to sell produce in Europe.
Organic darmers refused to use (some chemicals on their crops or feed antibiotics to their animals and good for them on that score. But to worry that giving traces of gm maize to their cows wikk damage the cheese?
The BBC has links to recent stories >>
See also
New Scientist >>
What do you think?
