Enhancement of the Environment for Toxic Fungi
Although for the most part health risks are the result of the genetic material newly added to organisms, it is also possible for the removal of genes and gene products to cause problems. For example, genetic engineering might be used to produce decaffeinated coffee beans by deleting or turning off genes associated with caffeine production. But caffeine helps protect coffee beans against fungi. Beans that are unable to produce caffeine might be coated with fungi, which can produce toxins. Fungal toxins, such as aflatoxin, are potent human toxins that can remain active through processes of food preparation.
No Long-Term Safety Testing
Genetic engineering uses material from organisms that have never been part of the human food supply to change the fundamental nature of the food we eat. Without long-term testing no one knows if these foods are safe.
Decreased Nutritional Value
Transgenic foods may mislead consumers with counterfeit freshness. A luscious-looking, bright red genetically engineered tomato could be several weeks old and of little nutritional worth.
Problems Cannot Be Traced
Without labels, our public health agencies are powerless to trace problems of any kind back to their source. The potential for tragedy is staggering.
Side Effects can Kill
37 people died, 1500 were partially paralyzed, and 5000 more were temporarily disabled by a syndrome that was finally linked to tryptophan made by genetically-engineered bacteria.
Unknown Harms
As with any new technology, the full set of risks associated with genetic engineering have almost certainly not been identified. The ability to imagine what might go wrong with a technology is limited by the currently incomplete understanding of physiology, genetics, and nutrition.
Potential Environmental Harms
Increased Weediness
One way of thinking generally about the environmental harm that genetically engineered plants might do is to consider that they might become weeds. Here, weeds means all plants in places where humans do not want them. The term covers everything from Johnson grass choking crops in fields to kudzu blanketing trees to melaleuca trees invading the Everglades. In each case, the plants are growing unaided by humans in places where they are having unwanted effects. In agriculture, weeds can severely inhibit crop yield. In unmanaged environments, like the Everglades, invading trees can displace natural flora and upset whole ecosystems.
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Some weeds result from the accidental introduction of alien plants, but many were the result of purposeful introductions for agricultural and horticultural purposes. Some of the plants intentionally introduced into the United States that have become serious weeds are Johnson grass, multiflora rose, and kudzu. A new combination of traits produced as a result of genetic engineering might enable crops to thrive unaided in the environment in circumstances where they would then be considered new or worse weeds. One example would be a rice plant engineered to be salt-tolerant that escaped cultivation and invaded nearby marine estuaries.
Gene Transfer to Wild or Weedy Relatives
Novel genes placed in crops will not necessarily stay in agricultural fields. If relatives of the altered crops are growing near the field, the new gene can easily move via pollen into those plants. The new traits might confer on wild or weedy relatives of crop plants the ability to thrive in unwanted places, making them weeds as defined above. For example, a gene changing the oil composition of a crop might move into nearby weedy relatives in which the new oil composition would enable the seeds to survive the winter. Overwintering might allow the plant to become a weed or might intensify weedy properties it already possesses.
Change in Herbicide Use Patterns
Crops genetically engineered to be resistant to chemical herbicides are tightly linked to the use of particular chemical pesticides. Adoption of these crops could therefore lead to changes in the mix of chemical herbicides used across the country. To the extent that chemical herbicides differ in their environmental toxicity, these changing patterns could result in greater levels of environmental harm overall. In addition, widespread use of herbicide-tolerant crops could lead to the rapid evolution of resistance to herbicides in weeds, either as a result of increased exposure to the herbicide or as a result of the transfer of the herbicide trait to weedy relatives of crops. Again, since herbicides differ in their environmental harm, loss of some herbicides may be detrimental to the environment overall.
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