As with other environmental issues, the advantages of using genetically modified organisms, or GMOs, must be weighed against their disadvantages. The conclusion may differ in different regions of the world, depending on available resources and the needs of the people.
We'll consider two types of traits in crops: herbicide tolerance and pest resistance. Herbicide tolerant plants are genetically modified organisms that can tolerate and survive a particular herbicide. Spraying the herbicide on the crop kills the surrounding weeds, but not the GMOs.
What are the disadvantages of growing this GMO crop? For one, more herbicides are used on fields, because the herbicides do not harm this particular plant. Herbicides are potential water pollutants. Also, consider that the farmer growing these crops is locked into buying the particular herbicide. The company producing the seed and herbicide has an unchallenged market (with no competitors), so prices can be high.
Another type of genetically modified plant is one that has been engineered to be pest resistant. A toxin, called Bt-toxin, kills many types of insect pests. The bacterial gene that codes for this toxin can be put into plants, allowing the plants themselves to ward off the pests. A big advantage of these plants is that they require much less pesticide, because crops can defend themselves.
One disadvantage of this GMO is that while the crop kills insects considered pests, it may also repel beneficial insects like pollinators. Also, over time, pest populations evolve, such that pesticide-resistant pest populations may increase. To control these pests, farmers may need to use larger doses of a pesticide. Additionally, secondary pests that are unaffected by the pesticide may increase if their insect competitors are killed by the pest-resistant plants.
A problem for both types of GMOs is the transfer of the trait to weeds. For example, in the US, many weed species have already acquired a gene for herbicide-tolerance. These so-called super weeds, including giant ragweed and pigweed, can tolerate all the herbicide a farmer can spray. They take over entire fields, stop combines, and are tough to clear by hand.
Who pays for these high-tech crops? It can be seen as an advantage that corporations have absorbed the tremendous cost and time of developing useful GMO products, because this saves taxpayers money.
However, several disadvantages can also be identified. First, the price of GMO seeds is higher, reflecting the corporation's time and financial investment. Also, corporations require farmers to purchase new seeds every year, instead of allowing farmers to harvest seeds for future use.
Now consider farmers who use non-GMO seeds and grow them organically. Sometimes the pollen from one field will fertilize the plants in another. In this way, the organic farm becomes contaminated and produces seeds that carry the GMO trait. Because the seeds are patented, the corporation can sue farmers whose fields are accidently pollinated by GMO plants. Also, if cross-pollination accidently contaminates fields of organic produce, the contaminated crop no longer qualifies as organic.