Thursday, November 29, 2007

Genetic Engineering Part 3

Virtually every genetically engineered organism released into the environment poses a potential threat to the ecosystem. To appreciate why this is so, we need to understand why the pollution generated by genetically modified organisms is so different from the pollution resulting from the release of petrochemical products into the environment.

Because they are alive, genetically engineered organisms are inherently more unpredictable than petrochemicals in the way they interact with other living things in the environment. Consequently, it is much more difficult to assess all of the potential impacts that a genetically engineered organism might have on the Earth's ecosystems.

Genetically engineered products also reproduce. They grow and they migrate. Unlike petrochemical products, it is difficult to constrain them within a given geographical locale. Finally, once released, it is virtually impossible to recall genetically engineered organisms back to the laboratory, especially those organisms that are microscopic in nature.

The risks in releasing novel, genetically engineered organisms into the biosphere are similar to those we've encountered in introducing exotic organisms into the North American habitat. Over the past several hundred years, thousands of non-native organisms have been brought to America from other regions of the world. While many of these creatures have adapted to the North American ecosystems without severe dislocations, a small percentage of them have run wild, wreaking havoc on the flora and fauna of the continent. Gypsy moth, Kudzu vine, Dutch elm disease, chestnut blight, starlings and Mediterranean fruit flies come easily to mind.

Whenever a genetically engineered organism is released, there is always a small chance that it, too, will run amok because, like non-indigenous species, it has been artificially introduced into a complex environment that has developed a web of highly integrated relationships over long periods of evolutionary history. Each new synthetic introduction is tantamount to playing ecological roulette. That is, while there is only a small chance of it triggering an environmental explosion, if it does, the consequences could be significant and irreversible.

Spreading Genetic Pollution

Nowhere are the alarm bells going off faster than in agricultural biotechnology. The life-science companies are introducing biotech crops

containing novel genetic traits from other plants, viruses, bacteria and animals. The new genetically engineered crops are designed to perform in ways that have eluded scientists working with classical breeding techniques. Many of the new gene-spliced crops emanating from laboratories seem more like creations from the world of science fiction. Scientists have inserted "antifreeze" protein genes from flounder into the genetic code of tomatoes to protect the fruit from frost damage. Chicken genes have been inserted into potatoes to increase disease resistance. Firefly genes have been injected into the biological code of corn plants. Chinese hamster genes have been inserted into the genome of tobacco plants to increase sterol production.

Ecologists are unsure of the impacts of bypassing natural species boundaries by introducing genes into crops from wholly unrelated plant and animal species. The fact is, there is no precedent in history for this kind of "shotgun" experimentation. For more than 10,000 years, classical breeding techniques have been limited to the transference of genes between closely related plants or animals that can sexually interbreed, limiting the number of possible genetic combinations. Natural evolution appears to be similarly circumscribed. By contrast, the new gene-splicing technologies allow us to bypass all previous biological boundaries in nature, creating life forms that have never before existed. For example, consider the ambitious plans to engineer transgenic plants to serve as pharmaceutical factories for the production of chemicals and drugs. Foraging animals, seed-eating birds and soil insects will be exposed to a range of genetically engineered drugs, vaccines, industrial enzymes, plastics and hundreds of other foreign substances for the first time, with untold consequences. The notion of large numbers of species consuming plants and plant debris containing a wide assortment of chemicals that they would normally never be exposed to is an unsettling prospect.

Much of the current effort in agricultural biotechnology is centered on the creation of herbicide-tolerant, pest-resistant and virus-resistant plants. Herbicide-tolerant crops are a favorite of companies like Monsanto and Novartis that are anxious to corner the lucrative worldwide market for their herbicide products

To increase their share of the growing global market for herbicides, life-science companies have created transgenic crops that tolerate their own herbicides (see "Say It Ain't Soy," In Brief, March/April,1997). The idea is to sell farmers patented seeds that are resistant to a particular brand of herbicide in the hope of increasing a company's share of both the seed and herbicide markets. Monsanto's new "Roundup Ready" patented seeds, for example, are resistant to its best-selling chemical herbicide, Roundup.

The effects of toxic chemicals in the environment is a huge topic best covered in a book title Our Stolen Future by Colborn,Dumanoski and Myers. The point of their argument being that toxic chemicals released into the environment find their way through the water supply and food chain into our bodies where they accumulate over time. Toxic effects only surface when levels in our bodies reach critical mass. The effects of the endocrine system are also too vast to list here. This is a subject for another discussion.

The chemical companies hope to convince farmers that the new herbicide-tolerant crops will allow for a more efficient eradication of weeds. Farmers will be able to spray at any time during the growing season, killing weeds without killing their crops. Critics warn that with new herbicide-tolerant crops planted in the fields, farmers are likely to use even greater quantities of herbicides to control weeds, as there will be less fear of damaging their crops in the process of spraying. The increased use of herbicides, in turn, raises the possibility of weeds developing resistance, forcing an even greater use of herbicides to control the more resistant strains.

The potential deleterious impacts on soil fertility, water quality and beneficial insects that result from the increased use of poisonous herbicides, like Monsanto's Roundup, are a disquieting reminder of the escalating environmental bill that is likely to accompany the introduction of herbicide-tolerant crops.

The new pest-resistant transgenic crops pose similar environmental problems. Life-science companies are readying transgenic crops that produce insecticide in every cell of each plant. Several crops, including Ciba Geigy's pest-resistant "maximizer corn" and Rohm and Haas's pest-resistant tobacco are already available on the commercial market. A growing body of scientific evidence points to the likelihood of creating "super bugs" resistant to the effects of the new pesticide-producing genetic crops.

The new generation of virus-resistant transgenic crops pose the equally dangerous possibility of creating new viruses that have never before existed in nature. Concerns are surfacing among scientists and in scientific literature over the possibility that the protein genes could recombine with genes in related viruses that find their way naturally into the transgenic plant, creating a recombinant virus with novel features.

A growing number of ecologists warn that the biggest danger might lie in what is called "gene flow"--the transfer of genes from altered crops to weedy relatives by way of cross-pollination. Researchers are concerned that manufactured genes for herbicide tolerance, and pest and viral resistance, might escape and, through cross pollination, insert themselves into the genetic makeup of weedy relatives, creating weeds that are resistant to herbicides, pests and viruses. Fears over the possibility of transgenic genes jumping to wild weedy relatives heightened in 1996 when a Danish research team, working under the auspices of Denmark's Environmental Science and Technology Department, observed the transfer of a gene from a transgenic crop to a wild weedy relative--something critics of deliberate-release experiments have warned of for years and biotech companies have dismissed as a remote or nonexistent possibility.

This article is from Jeremy Rifkin's new book The Biotech Century: Harnessing the Gene and Remaking the World (Tarcher/Putnam).

1 comment:

Jeannie said...

All the scientists are mad.