Genetically Modified Organisms (GMO)


Fate and Transport in the Environment

Exposure Pathway

Methods for Measuring Exposure

Strategies for Preventing Exposure

Methods for Monitoring in the Environment

Harmful Effects

Dose Response

Absorption, Distribution and Metabolism

Sites of Toxicity

Biomarkers of Disease

Risk Assessment


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Strategies for Preventing Exposure

Genetically modified foods currently sold internationally have passed risk assessments and are not likely to present risks for human health (WHO website). However, food safety experts have identified several possible human health hazards associated with GMOs. The hazards include the possibility of introducing a new allergen or new toxins to a food, a decrease in nutritional quality, and antibiotic resistance (Mellon, 2003).

In order to prevent potential hazards from entering the food supply, an extensive pre-market approval assessment is recommended. A pre-market safety assessment includes an investigation to determine the benefits and risks of each individual GMO. Due to the difficulties of applying traditional risk assessment procedures to whole foods, the concept of substantial equivalence was introduced to consider the intended and unintended changes that may occur in a food containing a GMO ingredient (CODEX). Substantial equivalence is considered the most appropriate strategy to date for the safety assessment of foods derived from biotechnology (WHO/EURO, 2000).

Substantial equivalence helps in the identification of potential safety and nutritional issues in a GM food. The structure of the safety assessment is determined by comparing the new food relative to its conventional counterpart. If a new food can be demonstrated to be substantially equivalent to an existing counterpart, the new food can be regarded as being as safe as that counterpart and no further safety considerations other than for the counterpart are necessary. A product may also be substantially equivalent to an existing counterpart except for defined differences and further safety assessments should focus only on those defined differences. There have been no examples to date of foods produced using genetic modification which could be considered to be not substantially equivalent to existing foods or food components (FAO website).

Currently, there are no standard protocols for testing GMOs before they are released into the environment (WHO website). Government regulations can vary from a company notifying authorities they are selling a biotech crop to strict government regulations around the testing, traceabiltity and labeling of GMOs. The Codex Alimentarius Commission is currently developing principles for human health risk analysis and the WHO Food Safety Program assists national authorities in the identification of foods that should be subject to risk assessment and recommends the correct assessments.

Example: U.S. Pre-Market Consultation
In the pre-market phase, manufacturers work in voluntary consultation with the FDA, USDA, or EPA, depending on the type of product being developed, to test the safety of new genetically modified products (Cockburn, 2002). The concept of “Substantial Equivalence” is used to determine if there are any differences between the genetically modified crop and its traditional counterpart, which is generally regarded as safe. Any differences identified are then tested by the developer using a variety of in vitro and in vivo studies to evaluate their safety. Once the manufacturer has completed the consultation process with the government agency the product is considered safe for consumption and approved for the market. No exposure limits are set by regulators and no attempts are made to monitor consumer exposures, although regulators do monitor for GMO’s that are not approved for human consumption (Taylor, 2003).

Consumer Strategies to Limit Exposures

For consumers who wish to limit their exposure to genetically modified foods, the best strategy is to eat fresh, unprocessed food, as most of these are not genetically modified (Greenpeace, GEO-PIE). Advocacy groups such as Greenpeace provide information for consumers on what types of genetically modified foods are on the market and how to avoid them. Consuming organic foods is another option. Processed foods labeled 100% organic are prohibited from containing GMO’s under the USDA’s National Organic Program regulations (USDA website). The possibility of gene flow between GM crops and organic crops, although very small, exists nonetheless and makes it difficult to be absolutely certain that organic products do not contain any traces of GMO’s.


20 Questions on Genetically Modified Foods. (n.d.). Retrieved September 26, 2003

Cockburn, A. (2002). Assuring the safety of genetically modified (GM) foods: The importance of an holistic, integrative approach. Journal of Biotechnology, 98, 79-106.

Codex Alimentarius Commission. Codex principles and guidelines on foods derived from biotechnology: prepublication. Food and Agriculture Organization of the United Nations.

Cornell University’s Genetically Engineered Organisms Public Issues Education Project (GEO-PIE). August 8, 2003.

Food and Agricultural Organization of the United Nations: Safety assessment of GM foods. (n.d.). Retrieved October 1, 2003

Green Peace True Food Guide. (n.d.). Retrieved September 25, 2003

Mellon, M. and Rissler, J. Environmental Effects of Genetically Modified Food Crops. Union of Concerned Scientists. June 2003.

Release of GMOs in the environment: is it a human health hazard?. A joint WHO/EURO - ANPA Seminar, September 2000.

Taylor, M., and Tick, J. Post-market oversight of biotech foods. The Pew Initiative on Food and Biotechnology. April, 2003.
USDA’s organic production and handling standards. October 2002.