Why All the Fuss Over GMOs Now?

This article appeared in the National Agricultural Biotechnology Council Report "World Food Security and Sustainability: The Impacts of Biotechnology and Industry Consolidation," 1999.

Genetic modification over decades, centuries, and even millennia, has helped agriculture meet the food needs of a world population that has grown from 300 million, in 1000 A.D., to 6 billion, in 2000 A.D. It is probably impossible to identify a food from a domesticated source that has not been genetically modified by humans prior to molecular biotechnology.

Genetic improvement started with selection of organisms with superior traits, followed by breeding for additional genetic improvement. The power of genetic modification, from the 10th millennium B.C. to the present, progressed from selection to hybridization, Mendelian genetics, quantitative genetics, induced mutation, fusion, somaclonal variation, and molecular genetics.

Molecular methods are the basis of modern biotechnology, providing new tools not only for more rapid but also more precise genetic improvement of organisms; these organisms are referred to variously as genetically engineered organisms (GEOs), genetically modified organisms (GMOs), or transgenic organisms.

Highly domesticated organisms - bacterial, plant, and animal - are genetically modified for improved end-use as food, feed, or fiber crops, as a microbe for fermentative production of a processed food (for example, beer, wine, bread, or miso), as an industrial product (for example, fuel ethanol), as an improved dairy animal, or as an egg or meat producer. These genetically modified organisms are more fit for our domesticated use and usually less fit for existence in the unprotected world.

Our quality of life today is already highly dependent on genetically modified microbes, plants, and animals. Genetic modification is an increasingly major contributor to our capability to provide food for twenty times as many humans in 2000 A.D. as in 1000 A.D. Our knowledge, data, and tools are enabling us to achieve more rational and directed genetic changes at the molecular level by transfer of genes and control of their expression. The new molecular approach enables genes (at most, a few in any one case) to be moved within and across species with greater facility than occurs naturally. Genomic sequencing is revealing much commonality in genes of bacteria, plants, and animals.

What do we know about environmental and human health risks from genetically modified organisms? The most important conclusion is that risk from a product is inherent to that product, not to the process by which it is made. If identical products are produced by either molecular or organismal genetic modification, then they pose identical risks.

We have substantial experience with organisms modified at the organismal level. In general, such products have been of low risk, but there are a few examples of problems, such as the introduction of kudzu, an exotic pasture legume that became an aggressive weed, and widespread use of corn with cytoplasmic male sterility that was subsequently found to be susceptible to southern corn blight.

We have less experience (about ten years) with molecularly modified organisms; however, no substantiated examples of significant risk to the environment or human health, relative to the products being replaced, has been documented by rigorous and replicated scientific evaluation. Of course, we must continue to be watchful for negative effects in order to assure improved product safety. Our major focus should be on ‘what is’ rather than on the never-ending and often untestable ‘what if’.

There are some process characteristics that help guide risk assessment, the most important element of which is asking the right questions. The involvement of only a few genes of known structure and function in molecular genetic modification helps focus risk-assessment in contrast to organismal processes that involve, for example, the estimated 30,000 or more different genes of a higher plant. This genetic roulette is much less predictable in organismal than molecular genetic improvement. However, genetically improved products should be evaluated for safety on a case-by-case basis, utilizing all of the available information, including experience, to guide the assessment.

The tools of molecular genetic modification continue to improve, and should reduce further concern over food and environmental safety.

Early use of kanamycin antibiotic resistance, expressed by a marker gene to indicate successful transfer of an accompanying target gene, has been criticized because of a theoretical concern that pathogenic microbes might become resistant to this antibiotic. The FDA reported in 1994 its extensive examination of this risk. Kanamycin is almost never used in human medicine due to its high toxicity and evidence of widespread resistance. Transfer, in the human gut, of the resistance gene to a pathogenic microorganism from a plant cell is extremely unlikely relative to the transfer of resistance from the much more abundant antibiotic-resistant microorganisms.

Products in the research pipelines, for the most part, do not have an antibiotic-resistance marker genes. Improved tools, such as genomic site-specific introduction and tissue and development stage-specific expressions, will make molecular genetic improvement even safer.

Other approaches, such as genetic sterility or organelle location of inserted genes, could diminish greatly the concern over gene escape in those areas where there are weedy relatives. Weedy relatives, of course, are not a concern with most domesticated crops in the U.S., such as corn and soybeans.

Editor’s note: In the next issue, Vegetable, Production and Marketing News will highlight a statement from the NABC on GMO regulations.