1. Is genetic engineering fundamentally new?

Pro-GM: Genetic modification is nothing new. People have manipulated foods and food crops for millennia, through methods ranging from fermentation to classical selection. Genetic engineering is just the latest form of biotechnology—the most precise method yet.

Anti-GM: Genetic engineering is fundamentally different from traditional methods of plant and animal breeding because it crosses biological barriers, transferring genes from one species to another.

2. Are foods from GM crops safe?

Pro-GM: There are no inherent differences between foods produced from genetically modified (GM) plants and those from non-GM crops. All living things contain DNA, and all DNA consists of the same four building blocks, known as nucleotides. By moving a piece of DNA from one organism into another, scientists are not introducing a "foreign" substance. The new gene merely prompts the modified organism to express a desired trait. Companies that wish to release a GM seed or the product of a GM crop are required to test the safety of that product. If the product is made from an organism containing a known allergen, it must be tested for safety. No one has substantiated a single human death, or even illness, as a result of consuming GM foods.

Anti-GM: There are too few independent (non-industry) studies of the health effects of GM foods to have confidence in their safety. In an experiment in Scotland, rats fed GM potatoes containing a gene for a protein, lectin, fared poorly and suffered internal organ damage. Pro-GM scientists have attacked the study, but at the very least it highlights the need for more research. The mistaken release into the food system of "Starlink" GM corn approved only for animal feed illustrates another danger—that of allergens being introduced into otherwise non-allergenic foods through genetic engineering.

3. What is the impact of GM crops on the environment?

Pro-GM: As it's practiced today, agriculture damages the environment more than any other human activity. Genetically engineered crops will ease that negative impact. Insect resistant GM crops, such as those containing the bacterial Bt gene (which makes the plant itself toxic to key pests), allow farmers to dramatically reduce their use of spray insecticides. Next-generation seeds may allow farmers to maintain high yields while using less water and chemical fertilizer. Potential problems with GM crops, such as the creation of "super weeds" and "super pests," are overblown by opponents, but to the extent those dangers are real they can be managed and prevented. For example, farmers can avoid promoting Bt-resistance in insects by planting non-GM acreage near each GM plot.

Anti-GM: Bioengineered crops will do wide-reaching damage to the environment. Insect-resistant crops may harm species that are not their target, such as monarch butterflies. On the other hand, the insects that GM crops are designed to kill could develop resistance to those crops, ultimately requiring farmers to use more aggressive control measures, such as increased use of chemical sprays.

More research is needed on the potential of GM crops to transfer their genes to other crops or wild relatives. Transfer of pesticide-resistant genes to related weeds may produce "super weeds" —those immune to commonly used control methods. Likewise, viral genes added to a plant to confer resistance may be transferred to other viral pathogens, leading to new, more virulent strains of the viruses. Gene transfer could also cause non-GM crops to be contaminated by GM crops in neighboring fields, threatening the rich crop diversity of many developing countries.

NEXT>>