The Internet can be a wonderful source of science information. Unfortunately, it also contains a great deal of false information on genetically engineered (GE) crops. Most people are not aware of the extensive pre-market testing that must be done before any GE crop is allowed to be commercialized. In reality, GE crops are tested 10-50 times the level of non-GE crops. The testing examines potential hazards and the likelihood of exposure to determine the overall risks for GE crops and derived foods.
When testing food for safety international agreed standards from OECD and WHO are the preferred protocols. A good reference that outlines the variety of categories to be tested can be found in the European Food Safety Authority journal article from 2011.
- Principles of Risk Assessment (4 subcategories)
- Molecular Characterization (2 subcategories)
- Comparative Assessment (5 subcategories)
- Toxicological Assessment (5 subcategories)
- Allergenicity Assessment (3 subcategories)
- Nutritional Assessment (2 subcategories)
For molecular, comparative assessments, toxicology and nutritional evaluations the data is straight forward with respect to food safety. However, one of these areas of investigation is very much misunderstood. The general public often reads of potential allergens being created by the process of gene transfer between species.
Determining whether a GE protein has potential to generate an immune reaction in people who consume food containing the GE protein is done with a weight of evidence approach as there is no 100 percent accurate method for determining the possibility of such occurrence.
All proteins are made of long chains of amino acids (20 different amino acids). Whether or not a given protein will generate an immune reaction is based on the exact sequence of amino acids that make up the protein. Each unique protein has a different sequence of amino acids. The average amino acid sequence that generates an immune reaction is 6-8 amino acids in length. There is a global database that contains amino acid sequences for known protein allergens. Every GE protein sequence must be compared against the known allergenic protein sequences in the database as part of the pre-market testing. No commercial GE protein sequence has ever matched any known allergen protein sequences (compared 8 amino acid lengths).
Some allergenic proteins are resistant to acid digestion. For this reason all GE proteins are tested for acid digestion (mimic stomach conditions). All GE proteins must be sensitive to acid digestion or another detailed set of tests must be done before the GE protein is given a passing grade. In rare cases skin prick tests are done with GE proteins on volunteers who have known allergies to specific proteins. Together all three types of analysis give a weight of evidence that a given GE protein will not cause allergenic reactions. Although the validity of these testing procedures have been challenged, there has never been an allergenic reaction documented to any commercial food derived from GE crops.
Until newer validated tests for potential allergenic proteins are developed the present system of weight of evidence testing for potential allergenic in all GE crops will continue to be an important part of the evaluation process for all GE crops
Together with toxicity, nutritional, molecular, compositional and allergy testing there are often whole food/feed animal testing of GE crops. A detailed review by the European Food Safety Authority of how these tests are done can be read here. They concluded:
“Many feeding trials have been reported testing GM maize, potatoes, rice, soybeans and tomatoes on rats or mice for prolonged periods, and parameters such as body weight, feed consumption, blood chemistry, organ weights, histopathology etc. have been measured. The food and feed under investigation were derived from GM plants with improved agronomic characteristics like herbicide tolerance and/or insect resistance. The majority of these experiments did not indicate clinical effects or histopathological abnormalities in organs or tissues of exposed animals. These studies can be used to assist the safety evaluation of GM plant derived food and feed and to reach conclusions on whether they can be considered as safe as their conventional counterpart.”
However, they also state:
“Once compositional equivalence has been established for such plants, feeding studies with livestock species have added little to their safety and nutritional assessment, other than to provide further reassurance that they are as safe and nutritious as their traditional counterparts.”
Recently food safety experts have been calling into question the need for whole food testing. But at present whole food animal testing is still part of the standard GE crop testing.
Many GE crops are grown with the use of the herbicide glyphosate. The Internet is full of scary stories after a recent press release by the IARC committee appointed by the WHO declared glyphosate to be a probable carcinogen. There has been a great deal of discussion about this determination as it goes against decades of research that found glyphosate is not carcinogenic . Further, detailed epidemiology studies found no causal relationship between any disease, or cancer. Until the IARC releases their full report the global toxicology community is left guess how the IARC made such a determination for glyphosate.
The German InterAcademy Panel Initiative on Genetically Modified Organisms report on the safety of consuming food derived from GE plants nicely encapsulated the global science opinion on the safety of food derived from GE crops:
“On the basis of existing scientific literature this report examines the potential risks for people who consume products of genetically modified (GM) plants. Taken into account are toxicity, the potential of causing cancer and food allergies, and the effects of consuming foreign DNA, including the DNA of antibiotic resistance genes. The report reaches the conclusion that in consuming food derived from GM plants approved in the EU and in the USA, the risk is in no way higher than in the consumption of food from conventionally grown plants. On the contrary, in some cases food from GM plants appears to be superior in respect to health.”
In 1987 the US National Academy of Sciences stated:
“There is no evidence that unique hazards exist either in the use of rDNA techniques or in the movement of genes between unrelated organisms.”
Almost three decades of research has confirmed this opinion. There is no doubt that every type of breeding has the potential to develop novel allergens or toxic compounds in food. Fortunately this rarely happens. With respect to GE crops and derived foods, the present pre-market testing protocols for all GE crops is extensive and effective giving the public confidence that food derived from GE crops is as safe, or safer than food from other breeding methods.