The terms "GMO" -- short for genetically modified organism -- and "organic" describe two types of food production methods used in modern agriculture. According to the U.N. Food and Agriculture Organization, between the years 2001 and 2005 the planting of GMO crops more than tripled worldwide, with 75 percent of the plantings concentrated in industrialized nations (see References 1).

Definitions "GMO" technically has a broad definition that has come to be understood in a much narrower sense since the introduction of genetically engineered plants into the food system. Broadly, genetic modification occurs whenever a plant breeder selects to cross two plants in hopes of producing offspring with a desired trait. Since the advent of genetic engineering, however, the term "GMO" typically describes plants that have been genetically engineered. Genetic engineering describes the introduction of a gene from a different species than the host so that the plant expresses a trait not genetically normal for its species, such as the production of pesticides. (See References 2)

Organic Regulations U.S. National Organic Program Regulations expressly forbid the use of GMOs in the production of organic food. The use of genetic engineering falls under the "excluded methods" described in the Terms Defined section of the regulation. Traditional breeding methods -- including tissue culture and in vitro fertilization -- are permitted, however. (See References 3)

Environmental Issues and GMOs Farmers and horticulturalists have been practicing plant breeding for thousands of years, but the relatively recent arrival of GMOs makes it difficult to assess their long-term environmental impact. Nonetheless, concerns exist over the potentially negative environmental impact of GMOs. Because they introduce genes not native to a particular species, the impact these genes will have if they enter wild plant populations is yet unknown. GMO crops are often engineered to produce pesticides or resist herbicides, so the potential for GMO crops to induce pesticide resistance in pest and weed populations could result in high pest populations that cause agricultural and environmental damage. The potential of these pesticides to harm nontarget organisms also raises concern. (See References 4)

Environmental Issues and Organic Systems Organic agriculture is also tied in to the green movement, but for different reasons. The stated goal of organic agriculture, according to the U.S. Department of Agriculture, is to produce food in harmony with the larger ecosystem. Organic systems avoid synthetic materials to control pests and boost soil fertility, instead enhancing natural processes that sustain plant and animal life in nature -- such as biological activity in the soil, crop rotation to control pests and diseases, and the use of natural predators to keep pest populations in check. (See References 5)