Dick Taverne's article was disappointingly shallow, not just because he regurgitated every half-truth and misleading mix of selected "benefits" attributed to GM foods by the PR and marketing gurus, but because he failed to think through the true balance of risks and benefits involved in specific GM applications.
Only two GM applications have achieved any significant market penetration: herbicide resistance and insect resistance. The supposed benefits of these applications need careful dissection.
Take herbicide resistance. Historically, weed killers have not been approved for use on food crops—conventional crops would be destroyed. Yet the farmer's need for weed control is understandable—weeds compete with crops for soil moisture and nutrients, reducing crop yields. Weeding is timely and costly, but necessary. GM herbicide-resistant crops allow for easy and effective application of weed killer without fear of crop damage. But this has an unexpected consequence: it means that weed killers can be sprayed directly on to food crops. GM crops therefore contain higher residues of herbicides than conventional crops. This is the true cost to the consumer, ignored by the biotech industry.
Some herbicides have been developed as "agricultural control agents"; a class of application where the herbicide is used to kickstart certain cereals and pulses, like soya, into the "desiccation (drying) stage," allowing for more economical harvesting. Obviously the herbicide used as this desiccation agent cannot be the same herbicide to which the crop has been genetically engineered to be resistant. So a GM crop that is resistant to Glyphosate will require a separate herbicide as a desiccant, such as Glufosinate. So some GM crops can get a double dose of pesticide residues. Exactly what benefit to the consumer is provided by this?
The food industry is obliged to conduct regular analysis of herbicide residues. The cost of this testing is rarely introduced into the GM debate. Glyphosate, the active agent involved with the main herbicide-resistant GM soya product, may well be at the lower end of the toxicity spectrum of herbicides, but that is not likely to change the average consumer's perception of this issue: the unpalatable principle of applying weedkiller to foods.
As for pesticides, surveillance data confirms that in Britain, most conventional food crops have minimal incidences of pesticide residue. Farmers generally manage their crops well, with established integrated crop management systems and effective adherence to pre-harvest intervals (PHI—the period between the last pesticide application and harvesting). Organic growers are similarly diligent, with approved organic pesticides.
GM insect resistance has been given a spurious validity by association with traditional organic growing practices. The bacterium Bacillus thuringiensis (Bt) has naturally evolved as pathogenic to many insects. Organic growers have long produced slurries of Bt and used it as a "natural insecticide" spray. Bt acts by producing a toxin poisonous to insects. But when sprayed upon crops, this Bt toxin is a surface toxin only. Organic growers apply a PHI just as carefully as conventional growers do with synthetic insecticides. Assuming organic crops are washed before preparation and consumption, the amount of Bt toxin absorbed by consumers is negligible.
Biotechnologists have created GM crops with Bt toxin throughout crop tissue fluids, by introducing the Bt gene into food crops. The claim that the Bt toxin is "natural" is therefore highly contentious, as there is nothing natural about Bt toxin existing as such a "systemic" pesticide. Additionally, there can be no PHI with GM insect-resistant crops. Genes cannot be programmed to switch off a set number of days before an unpredictable harvest date. GM insect-resistant crops will be therefore harvested and consumed with the maximum biologically active concentration of Bt toxin present within their tissues. Not a comforting thought to the consumer.
To make matters worse, there is no established MRL for the Bt toxin, because it has traditionally been classified as natural. The food industry has not asked why this systemic use of Bt toxin should not trigger the introduction of MRLs for Bt toxin.
The biotechnology companies are not likely to focus on the potential disadvantages of their products. Had the industry's leading scientists done so, instead of being blinded by the elegance of the GM technology, we might have been spared the stresses of the last few years. Regrettably, Dick Taverne's article adds nothing to this debate. Nor does he provide any support to the potential benefits of GM technology in the field of medicine by associating it with the tawdry experiences of the food industry over the last decade.
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