New risks in genetically engineered crops (28/10/2003)

This article puts the recent UK findings in a wider context of research on the agronomic and environmental impacts of GM crops.
UK study finds new risks in genetically engineered crops
 By Peter Rosset

A major new study on the environmental impact of genetically engineered crops adds yet another concern to the growing list of ecological risks associated with such crops, writes Peter Rosset, biologist and co-director of the Institute for Food and Development Policy, also known as Food First, based in the United States.

The authors set out to answer a rather narrow question: whether plant and animal biodiversity is affected by the change in herbicide use in fields planted with crops engineered to tolerate proprietary brands of herbicide.

The study was flawed from the start. For one, the authors compared only three GE crops -- beets, canola and maize -- with 'their' herbicides, to conventional, Green Revolution-style non-GE crops, which use other herbicides.

A better experimental design would have also compared the herbicide-guzzling GE crops with ecologically-managed crops that use no herbicides at all. They also failed to ask any questions at all about the transgenic nature of the crops, choosing instead to focus only on a secondary effect, the impact of changing patterns of herbicide use.

Nevertheless, the study found that there were very serious impacts on biodiversity. In two of the three crops studied, herbicide use drastically affected plant biodiversity and consequently also had very negative affects on birds, bees, and butterflies. This raises the spectre of widespread above-ground ecosystem disruption in areas with broad use of herbicide-tolerant crops.

This risk should be added to the long list of other potential risks already found by other researchers. With regard only to the effects of herbicides in GE crops, there are also serious concerns about effects on below-ground biodiversity -- and thus soil fertility -- from the build-up of herbicides in the soil. It also seems that herbicide-tolerant GE crops are in some cases more susceptible to plant diseases and in general may be less vigorous than normal varieties.

The imprecise nature of the insertion of foreign genes into crop varieties also produces completely unexpected problems, like the stem splitting of some herbicide-tolerant soy varieties under high temperature conditions, leading to heavy yield loss for farmers.

This is in addition to the fact that herbicide-tolerant GE crops already yield an average of 5 percent less than normal varieties.

While herbicide-tolerant varieties account for the largest share of GE crops, so-called "Bt crops", which are engineered to contain their own pesticides, are the second most common type. Here a whole range of other ecological risks have been discovered. For example, Swiss researchers have found that the Bt pesticide kills not only 'target' pests but also many other insects which are actually enemies of crop pests because they are predators and parasites that feed on them.

Mathematical simulations at the University of California show that this effect, which amounts to the suppression of natural population control of pests, often cancels out the pest control effect of the Bt gene, even as pests themselves rapidly develop resistance to the Bt. The likely outcome after several years of planting Bt crops is that the farmer will be faced with greater, more uncontrollable pest problems, as the insect biodiversity that once worked in his favour will no longer be present.

Moreover, researchers associated with the US Environmental Protection Agency (EPA), and others, have found that the Bt pesticide persists in the soil long after the crop has been harvested, with major negative impacts on soil biodiversity and possible negative effects on soil fertility.

As if this weren't enough, the GE scandal in Mexico, where local maize varieties developed over millennia by indigenous peoples have been contaminated by GE pollen from illegal plantings of GE varieties, grows worse and worse, with new revelations coming out all the time. The latest study, carried by peasant and indigenous organisations themselves, found not only that the contamination is much more widespread than previously reported but also that there are cases of multiple contaminations where a single plant displays several transgenes that each came from a different patented variety.

The most serious aspect of this contamination of local varieties comes from preliminary evidence that a 'promoter' gene inserted in all GE varieties may introduce genetic instability into these 'creole' varieties, potentially leading to their degradation and eventual loss after having been generated over thousands of years of crossing and selection.

It seems that each new study adds new risks to an already overflowing list. In many cases these are risks --like lower soil fertility, reduced natural population control of pests, and loss of local varieties-- that will effect poor farmers more severely than wealthy farmers. Poor farmers lack cash to buy chemical fertilisers and pesticides and depend on locally-adapted native crop varieties. For them these risks of GE crops clearly threaten their livelihoods.

The question is, when will governments take the precaution seriously and ban international trade and planting of these unnecessary and dangerous crop varieties? (END/COPYRIGHT IPS)

(*) Peter Rosset is a biologist and co-director of the Institute for Food and Development Policy, also known as Food First (http://www.foodfirst.org ), based in the USA.

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