TONY FERNANDEZ
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s world trade issues surrounding biotech foods heat up, there is an increasing need to distinguish crops containing genetically modified organisms (GMOs) from non-GMO crops. Worldwide, the major crops affected include corn (maize), soybeans, canola, and cotton. In some countries, specific
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GMO food-labeling requirements, but also in those wanting to export food products into countries with restrictions. There isn’t just one method for determining GMO levels in food, however, and variability among test results is high. The two most common approaches to GMO detection are polymerase chain reaction (PCR)-based methods, which
Variability in methods creates a strong need for international standardization of GMO testing. GMOs, or “events”, are unapproved for food use. In such cases, even trace amounts of a particular GMO are unacceptable in products intended for human consumption. But it’s no longer just a question of whether a food contains a specific GMO. Several countries, including Japan and members of the European Union (EU), have food-labeling laws that incorporate threshold levels. Foods containing soy or maize ingredients with GMO material above the threshold level must be labeled “genetically modified”. To comply with these food-labeling requirements, accurate methods for determining the amount of genetically modified material in food are needed. In the EU, foods containing soy or maize ingredients with >1% GMO content must be labeled “genetically modified”. Japan has set the level at 5% for soybeans, but it has not set a level for corn because of the potential for crosspollination. Australia and South Korea have also indicated that they will include threshold levels in their GMO foodlabeling laws. In the United States, there is no mandatory requirement for labeling foods that contain GMOs. Despite pressure from consumer advocacy groups and Congress, the U.S. Food and Drug Administration (FDA) maintains that genetically modified foods are “substantially equivalent” to conventional foods and therefore do not require labeling, unless the nutritional content has been altered or the product contains known allergens. The need to verify GMO levels in food has created a new demand for analytical testing, not only in countries with
detect genetically modified DNA sequences, and immunoassays, which measure levels of proteins expressed by transgenic genes. Laboratories around the world are developing new methods for detecting GMOs in food, but there is no agreement regarding the validity of tests. Currently, there are no internationally recognized methods or standards for quantifying GMO levels in food. It’s another case of science trying to catch up with policy. Standards and measurement agencies around the globe, however, are working to change that.
Toward standardization To support European legislation, the Institute of Health and Consumer Protection (IHCP), which is part of the European Commission’s Joint Research Centre (JRC), in Ispra, Italy, has been heavily involved in validating methods for GMO detection through its Food Products Unit. One of its first efforts in this area was to establish a collaborative study for the qualitative detection of genetically modified soybeans and maize. The study involved 41 laboratories, 29 of which actually submitted results, from EU member states, Switzerland, and the United States. Participating laboratories were instructed to follow standard PCR protocols but were allowed to choose any DNA-extraction and PCR procedures that were compatible with the given protocols. The participants, however, were not allowed to alter the primers (35S promoter and NOS terminator) that determine the DNA target sequence. Results from this ring
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Ready soy and Bt-11, Bt-176, and MON-810 in maize with less degradation using dry mixing techniques,” says Pauwels. The new CRMs are expected to be available by the end of 2000. The U.S. National Institute of Standards and Technology (NIST) has also put standard reference materials for GMOs high on its list of priorities for the next fiscal year, says Willie May, chief of NIST’s Analytical Chemistry Division. Although specifics of the project have not yet been established, NIST says it will not duplicate ongoing efforts by other national standards laboratories, such as IRMM. “First, we need to see if the IRMM standards meet U.S. needs. In cases where there are already standards that could serve the purpose, we would confirm the accuracy of the certified values and then direct
customers to them,” says May. Meanwhile, the U.S. Department of Agriculture (USDA), through its Grain Inspection, Packers, and Stockyards Administration (GIPSA), is taking the task of standardizing methods for the detection of genetically modified grains into its own hands. According to Steve Tanner, director of GIPSA’s Technical Services Division, GIPSA is planning to open a biotech reference laboratory in Kansas City, MO, later this summer to assist in the standardization efforts. Once the laboratory is set up, GIPSA is going to start a program for accrediting private, independent
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study, which was completed in June 1998, showed that GMOs can be consistently detected in soybean and corn flour, provided the sample contains at least 2% genetically modified material (J. AOAC Int. 1999, 82, 923–928). In addition to establishing a validation program for PCR-based methods, IHCP also organized a collaborative study in which 38 laboratories performed qualitative GMO tests using a commercially available diagnostic kit manufactured by Strategic Diagnostics, Inc., (SDI). The test kit uses an enzyme-linked immunosorbent assay (ELISA) to detect the protein in Roundup Ready soybeans that makes the plants resistant to the herbicide Roundup. All but one laboratory submitted results, suggesting the kit is relatively easy to use, and, according to IHCP, the results were promising. For samples containing
