explains why genetically engineered crops have become controversial and describes how, with a change of focus, they could help achieve a new Green Revolution
The debate over genetically engineered crops has generated much heat, and very little light or wisdom. It has been particularly impassioned in Europe. That is not surprising. The Europeans are very wary of governments and scientists telling them not to worry. They remember the Mad Cow experience all too well.
European, and for that matter American, consumers have seen few benefits from genetically engineered crops. American farmers (and the biotechnology companies) have been the primary beneficiaries. Bt corn (which produces a bacterial-based insecticide) is very effective against the European cornborer that caused a billion dollars worth of damage in 1997. And herbicide resistant soybean is profitable in weed control, especially for farmers following no-till rotations to improve soil conservation.
Many farmers have made significant profits. That is why they have been so keen to buy the new seeds. Worldwide, over 40 million hectares were planted to genetically engineered crops in 1999. In the
United States of America these varieties accounted for half the
soybean and cotton and a third of the corn (maize) hectarage.
The transferred genes may escape from cultivated crops into wild relatives (or to organic varieties on nearby farms). This is a justified concern. Genes from existing commercial crops can and do pass to organic crops, and vice versa, and genes from both transfer to wild relatives. Even self-pollinated crops, such as rice, will cross with wild rices. Such risks may be higher in developing countries, since wild relatives are often common. But the key question is whether genes remain in the wild relatives and whether this results in adverse ecological effects, such as the production of super-weeds. Only extensive, well-designed and monitored field tests will give us the answers.
Another significant risk the potential for pests to evolve resistance to the toxins produced by Bt genes is well known. Setting aside non-Bt areas as refuges is one answer. Nevertheless we will need to anticipate the eventual breakdown of control.
Bt is regarded as a safe insecticide, since it mostly kills pest caterpillars, leaving beneficial insects unharmed (and for this reason is often used as a key pesticide by organic farmers). Recently, in a much publicized experiment, pollen from Bt corn was shown to kill caterpillars of the Monarch butterfly. It was not a surprising result. The Bt toxin kills most caterpillars, not just the European cornborer. But in the field, concentrations of corn pollen fall away very rapidly from the edge of the crop. Beyond 3 metres the pollen load on neighbouring milkweed plants the natural food of the Monarch caterpillar will be safe for the caterpillars.
Wherever Bt cotton has been grown in the United States of America and China there has been a significant reduction in insecticide use. Pesticide poisoning has become less common and butterflies and birds have returned to the environment.
The most serious health risk is that transferred genes may increase allergies, through the introduction of new proteins to foodstuffs. Allergies can be tested for, where known, but there may be surprises.
Other fears have less scientific basis. There is no reason to suppose that the process of gene transfer confers a health risk. Neither is there any a priori reason why ingesting pieces of transgenic DNA is likely to be hazardous, any more than the large quantities of DNA from numerous sources ingested every day in normal diets.
But, on balance, many European and some American consumers feel the risks outweigh the benefits.
For the developing countries the balance may turn out to be rather different. It is clear that they urgently need more food some 800 million people in the world are chronically undernourished and some 180 million children are severely underweight for their age. Many die as a result.
By the year 2020 there will be an extra 1.5 billion to feed. That is a tall order; a challenge as great as that which faced the Green Revolution 30 years ago. Some argue it is simply a problem of unequal distribution. If poor people were not poor they could buy the food they need. This is true, but oversimplistic and not very helpful. There are no signs that the world is about to engage in a massive redistribution of wealth.
That is not going to be easy. In the early years of the Green Revolution the yields of the major cereals (rice, maize and wheat) were increasing at about 40 kilograms (kg) per hectare per year. At the peak, the rate was 60-80 kg, but in the recent decade it has gone down again, to about 40 kg.
I believe we need a new revolution a Doubly Green Revolution that repeats the successes of the old but in a manner that is environmentally friendly and much more equitable. This means applying modern ecology to the development of sustainable agricultural systems. But it is also going to need the application of modern biotechnology to help raise the yield ceiling, to produce crops resistant to drought, salinity, pests and diseases, and to produce new crop products of greater nutritional value.
Significant progress is being made. Chinese scientists, with funding from the Rockefeller Foundation, have produced a new rice variety using tissue culture, called La Fen Rockefeller, that is providing farmers in the Shanghai region with 15 to 25 per cent increases in yield. Scientists in West Africa have also used this technique to cross the high yielding Asian rices with the traditional African rices. The result is a new plant type that looks like African rice during its early stages of growth (in particular, it is able to shade out weeds) but becomes more like Asian rice as it reaches maturity, resulting in higher yields with few inputs.
But, the most significant achievement has been the introduction of genes that produce beta-carotene the precursor of vitamin A in the rice grain. Beta-carotene is present in the leaves of the rice plant, but conventional plant breeding has been unable to put it into the grain. Dr. Ingo Potrykus of the Swiss Institute of Plant Sciences in Zurich, who carried out the work with Rockefeller and Swiss Government funding, transferred one bacterial gene and two daffodil genes. The transgenic rice grain has a light golden-yellow colour and contains sufficient beta-carotene to meet human vitamin A requirements from rice alone. Over 100 million children suffer from vitamin A deficiency and 2 million die each year indirectly as a result.
Dr. Potrykuss team has also added a gene from the French bean to rice that increases its iron content over threefold. The number of women of childbearing age who are iron-deficient is over 400 million and anaemia is a major cause of death at childbirth.
Of course, before the new rices are released there have to be extensive trials. We have to examine potential risks. Are there any health hazards? In particular could allergies have been transferred? We need to know what effects the beta-carotene might have on insects that suck the grain.
There may be other concerns. Some may feel it is better, despite the cost and logistics, to provide children with vitamin A tablets. Others may believe it is desirable for children to get their vitamin A from homegrown leafy vegetables. I tend to agree with them, but realistically it is going to be many years before the poor farmers in the seasonally arid regions can grow vegetables throughout the year.
Realistically, the public sector cannot and should not compete with the biotechnology companies. Somehow we have to build partnerships between them. One answer is for the private sector to market seeds for the commercial farmers, at the same time making genomic information and technologies available to the public sector for poor farmers. An important test of such an approach will be to persuade the various patent holders to donate to plant breeders in the developing countries the technologies used in producing vitamin A rice
Professor Gordon Conway is President of the Rockefeller Foundation. His book, The Doubly Green Revolution: Food for All in the 21st Century, is published in paperback by Cornell University Press.
PHOTOGRAPH: Chan Yajiang/UNEP/Topham
Contents | Editorial K. Toepfer | Critical crossroads | Genetically engineered crops... | Sustainable solutions | Protect elephants | Getting it together | CITES: 2000 and beyond | At a glance | Competition | Interpol alert | Deep waters, high stakes | Tall trees and bottom lines | Globalizing solutions | Global Biodiversity... | Walking on the wild side... | Voices of the Earth | Millennium massacre