The Environmental Impact of Genetic Engineering

Since the genetic engineering of plants is a very new science, many of its long-term effects are not known. Plants are living, mutating, reproducing organisms, so it is impossible to predict with precision the effects of altering a plant's genetic make-up, releasing new plant forms into the environment, or introducing new plants to the food chain. As Stilwell states, "the interaction of GMOs with other complex biological systems, such as the human body or natural ecosystems, cannot, in many cases, be anticipated or fully tested before commercial release" (1999). Therefore, we can only hypothesize as to the probable effects that genetically engineered crops will have on our environment. Although there are some overall risks involved with genetic engineering, the particular varieties of genetically engineered plants have, in addition to the more general risks, their own distinct probable environmental consequences and side effects. Competition and cross-pollination between genetically engineered and naturally occurring species, as well as insect- and herbicide-resistant crops, are just some of the anticipated negative consequences of genetic engineering that are now becoming realities.

When more plants are engineered to be grown in any climate or any soil, farmers will have the opportunity to override natural environmental balances, introducing previously unsustainable crops in areas previously unable to support them. However, introducing new plant life into delicate ecosystems carries environmental consequences. "Transgenic [genetically altered] crops [could gain] a competitive advantage over native plants, potentially causing serious ecological disruption" (Anderson 1999). The new organisms upset the symbiotic ecosystem and could also bring viruses or pests that were never before in that area. This could harm native plants that have not formed a natural resistance to these unfamiliar viruses and pests. If native species are endangered or destroyed because of this, their delicate relationships with other organisms-insects, birds and other plant life-are destroyed forever. Like a ripple, a change in balance when one organism is disrupted eventually affects every other organism in the ecosystem.

Another disruption in the ecosystem could occur due to cross-pollination between conventional and genetically engineered crops. Cross-pollination could "transfer advantageous traits to wild plants, which could then become more vigorous" (Anderson 1999). This new generation of "super weeds" may be resistant to the herbicide usually used to control it, or contain pesticides within the plants' cells that could kill or otherwise harm the insects and other animals that feed off them. The United Kingdom's National Institute of Agricultural Botany reported in April that a hybrid "super weed" may have been created after canola pollen was taken up by wild turnips growing nearby. According to Betts, "some of these hybrid plants have proven to be resistant to the herbicide for which the canola was engineered to be resistant" (1999). The complex symbiotic relationships between the different organisms within an ecosystem create mutual dependence and reliance. A change or disruption of one organism affects all of the organisms in the ecosystem.

Many crops have been engineered to produce a pesticide (Bacillus thuringienis, or Bt) in every cell, which kills certain insects that eat the crop. These crops with a built-in pesticide were grown on 7.7 million hectares worldwide in 1998 (Anderson 1999). Three main problems result from genetic engineering involving Bt: increased insect resistance to the pesticide, endangerment of insect populations, and soil damage. With increased and continual exposure to Bt, targeted pests develop resistance to this pesticide. Harmless species of insects that eat the pollen or other parts of the crop also ingest the pesticide and may be killed. In addition, the active forms of Bt in some kinds of genetically engineered crops can bind to soil and stay present even after the crop is gone.

Bt has been used as an occasional topical biological pesticide for many years. Now that it is being engineered into the genes of the crops, "insects are continually exposed to the toxin, and are therefore under constant pressure to develop resistance" (Anderson 1999). With time and evolution, organisms change and adapt to their environment. Since insects are increasingly exposed to the pesticide, even ingesting it on a daily basis, the US Environmental Protection Agency warns that insect resistance to Bt "poses [a threat] to the future use of Bt pesticides"(2000). Continued use of Bt is crucial for environmental health, as Bt is one of the few biological pesticides that can be used on organic crops. With insects becoming increasingly resistant to it, Bt will no longer be an effective method for controlling pests, and we will lose one of the world's most important biological pesticides.

Since Bt is produced in every cell of the genetically engineered plant, organisms (whether insect, human, or other creature) that eat the crop therefore ingest the pesticide. In its naturally occurring form, Bt needs enzymes that are present only in certain insects' digestive system in order to be activated. Anderson notes, though, that in many of the genetically engineered crops, Bt is already in its active form and can therefore harm a wider range of insects, including insects lacking the Bt-activating enzymes (1999).

Many harmless insects are affected by active Bt, such as Monarch caterpillars, lacewings, and bees, as well as other life forms further up the food chain that feed off the insects that have eaten the Bt crops. In laboratory tests, 44 percent of the Monarch caterpillars that ate leaves laced with Bt corn pollen died within four days. No caterpillar deaths were recorded among Monarchs that ate leaves with normal corn pollen or no pollen at all (Woodworth 1999). The lacewings suffered from disruption to their development and increased mortality, while bees had difficulties learning to distinguish the different smells of flowers. Finally, female ladybirds were fed on aphids that had been eating transgenic potatoes, and when compared to ladybirds fed on a normal diet, they laid fewer eggs and lived half as long (Anderson 1999). Even though the detrimental effects of active Bt on living organisms have been demonstrated repeatedly and the long-term effects on humans are not yet known, Bt crops continue to be planted.

When "insect resistant" crops decompose, the active forms of Bt do not disappear from the soil. According to Anderson, "unlike naturally occurring forms of Bt, [its active forms] are not degraded by microbes, nor do they lose their capacity to kill insects"(1999). This seriously disturbs soil ecology and harms the many microorganisms found in fertile soil. "Deviations in the numbers and kinds of soil organisms may influence the fertility considerably by decreasing the [soil's] ability to retain water and nutrients" (Suurkula 1999). Also, soil organisms can mutate and change with the new DNA and create new soil microorganisms, potentially dangerous to other soil organisms, plants, and even humans. According to Suurkula: "Experimental findings confirm that vector genes (the Bt gene introduced to the crop) can promote transfer of genes between soil microorganisms. Other . . . findings show that vector genes can be transferred from GE plants to soil microorganisms. Taken together, this means that there are compelling reasons to consider the possibility that the cultivation of genetically engineered plants may lead to transfer of genetic material between soil microorganisms to a hitherto unprecedented extent" (1999). This means that not only are we releasing new organisms into our environment, but we are setting the stage for transfer and mutation of genes already present.

To date, approximately 50 percent of the United States soybean crop has been genetically engineered to be herbicide resistant. This means that they have had a "code" added to their genetic makeup that keeps them from being harmed by topical herbicides applied to kill surrounding weeds. The most obvious problem with this kind of crop is that larger amounts of herbicides can now be used without harming the crop. This leads to more run-off and ground water pollution as well as increased danger for farm workers due to exposure to greater amounts of poison. This also means that with increased use and cross-pollination, weeds can become resistant to the herbicide. After ten sprayings in 15 years, one weed "survived seven times the herbicide concentration that killed other plants" (Anderson 1999). Researchers in Canada and Australia have "found that the populations of herbicide-resistant wild oat are higher than was documented in 1996 and that fields have more combinations of resistance. For example, more than half the fields in both townships had some herbicide resistance, and many of the fields were resistant to two or more groups of herbicides" (Lutz 2000). With increasingly large numbers and amounts of herbicide being used, current herbicide types and dosage levels lose their effectiveness. This escalates into the production of new herbicides, increased quantities of herbicides unleashed on the environment, and the resultant need to re-engineer GE plants to be resistant to the new herbicides.

Applying large amounts of herbicides also presents a danger to all herbaceous plants, threatening extinction not only of harmful weeds but also beneficial plants, fish, and wildlife. Ho believes "the use of highly toxic . . . non-discriminating herbicides threatens to lead to large scale elimination of indigenous species and cultivated varieties, damaging soil fertility and human health besides" (1996). Plants that are not able to form resistance to the herbicide will be killed off, gradually becoming extinct. The Royal Society for the Protection of Birds and English Nature in the UK believes that "increased use of these herbicides will kill the weeds which support the insects and produce the seeds fed on by birds" (Anderson 1999). Once again, we see that the extinction of a weed has far-reaching effects and can harm other species that have formed symbiotic relationships with the weed. Additional research indicates that glyphosate (the main active ingredient in most herbicides) "can kill fish in concentrations as low as 10 parts per million, that it reduces growth of earthworms and increases their mortality and that it is toxic to many of the beneficial mycorrhizal fungi which help plants to take up nutrients from soils." It is also the third most commonly reported cause of pesticide-related illness among agricultural workers in California (Anderson 1999). Increased use of dangerous poisons affects not only the weeds, but can harm soil, ground water, insects, animals, and humans. Organisms must either adapt to the environment or perish; when humans add to or change elements within it, all organisms are eventually affected.