| VICUS.COM (14 March 2000) — The practice of mixing genes to improve crop quality and yield is not new. Prior to the development of recombinant DNA technology, success in this field was achieved with very little understanding of the biochemical mechanisms that determined the selected traits.
Every time a cross was made, tens of thousands of genes were mixed and reorganized, largely at random. Breeders then kept the preferred offspring, while discarding the descendents that lacked desirable traits or exhibited undesirable properties.
The advent of recombinant DNA technology for genetic manipulation provides biologists with a more powerful and selective tool. It extends the range of biological materials from which genes can be accessed. It also permits scientists to be very specific in altering the genetic makeup of new crop varieties. If done correctly, the promise of greater crop yields and an end to world hunger is possible. Done, incorrectly, it could be the incarnation of your worst science fiction movie.
Seven desirable outcomes from altering the genetic makeup of new crop varieties
- Altered plant fats and oils to improve health
- Environmentally benign herbicides
- Longer shelf life of foods at full ripeness
- Methionine- and lysine-enhanced grain and legume proteins
- Plant foods that deliver immunizing antigens
- Reduced world hunger
- Resistance to pests, and diseases
| Health Risk |
Concerns |
Scientific Support? |
| Toxicity |
Genetic manipulation could enhance natural plant toxins by switching on a gene with toxic effects. |
No scientifically valid study. |
| Allergies |
People with allergies could be exposed to proteins they react to without knowing it (eg, if a peanut, wheat, or shellfish gene, was transplanted into corn. |
A few years ago, a Brazil nut gene spliced into soybeans induced allergies in people sensitive to the nuts. |
| Bad nutrition |
Foreign genes might alter the nutritional value of food in unpredictable ways. |
The Journal of Medicinal Food reported that concentrations of phytoestrogens (thought to protect against heart disease and perhaps cancer) were lower in genetically modified soybeans vs traditional strains. |
| Antibiotic resistance |
When a foreign gene is spliced into a plant or microbe, a marker gene helps determine if the first gene was successfully taken up. Most markers code for resistance to antibiotics and might be passed on to disease-causing microbes in the intestines of people who eat altered food. This could contribute to the public-health problem of antibiotic resistance. |
No scientifically valid study. |
| Environmental risks |
|
| Losing a safe natural pesticide |
Among genetically modified products are crops with a gene from the soil bacterium Bacillus thuringiensis (Bt) that produces a protein toxic to insects. Overexposure to Bt will help insects become resistant. |
No scientifically valid study. |
| Harm to innocents |
In lab studies, monarch butterfly caterpillars that ate milkweed dusted with pollen from Bt corn died or developed abnormally. Ecologists worry that other “nontarget species” could be harmed. |
Letter to the editor, Nature. |
| Superweeds |
Insect resistance and herbicide tolerance—may be passed on to wild plants, particularly weeds an then an advantage over competing plant species |
One report of herbicide-tolerant canola cross- pollinated with a related weed species, producing a herbicide-tolerant descendant. |
John Russo, Jr. PharmD, is senior vice president of medical communications at Vicus.com. He is a pharmacist and medical writer with more than 20 years of experience in medical education.
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References:
Day PR. Genetic modification of proteins in food. Crit Rev Food Sci Nutr. 1996; 36 Suppl:S49-67. Losey JE; Rayor LS; Carter ME. Transgenic pollen harms monarch larvae [letter]. Nature, 1999; 399(6733):214.Tangley L. How safe is genetically modified food? (transgenic foods could trigger allergies, antibiotic resistance, and other health problems). U.S. News & World Report, July 26, 1999 v127 i4 p40. |
