Possible environmental hazards

        A concern about whether transgenic crops cause damage to the natural environment. One example includes pollen from transgenic corn, which has been suggested to kill the Monarch butterfly larvae. It has been shown that hybrid corn expresses a bacterial toxin in its pollen, which is then dispersed over 60 meters by wind. In this range, the corn pollen is deposited on other plants near cornfields where it can be ingested by non-target organisms including the monarch butterfly. These butterflies have been found to eat less, have a slower growth rate and higher death rate . A second example is the hybridization of crops with nearby weeds. This could cause these weeds to attain resistance to herbicides or other things that we have been trying to avoid for many years. Genes that provide resistance to viral disease or other traits allowing them to survive in their environment could end up benefiting weed populations around a crop field. This trait could make that population more difficult to control. To date, there has been little evidence to support this theory.

        On other side of the coin are the notions that support the use of transgenic crops. The potential benefits of which are quite obvious, including such things as increased yields (to feed a growing population), decreasing the use of pesticides (to save the environment and the cost of pesticides), and the production of novel crops (such as providing crops with increased nutritional value) . Being able to retrofit any crop to our desires is a powerful concept, especially with the changing climates of today.

        The potential for reduction in pesticide use or the substitution of less environmentally hazardous pesticides for those currently used on conventional crops has been proposed as a benefit of certain genetically engineered (GE) crops. This was certainly the case for genetically engineered corn and cotton varieties incorporating Bt genes for resistance to certain classes of insects, where the insecticidal compounds produced by the plants were expected to negate the need for additional insecticide applications to control the targeted pests. GE herbicide-tolerant crops are designed to be used with specific herbicides, so reductions in pesticide use might be realized if switching to a new herbicide application program compatible with a particular GE crop requires less pesticide than the pesticide applications it replaces. Unfortunately, it is difficult to directly compare the impact of these substitutions because application rates, as well as toxicity and environmental hazards, vary for different herbicides. Pesticide use patterns also change for reasons unrelated to the switch to GE crops, and this can complicate comparisons made over time.