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I read that GMO crops gain market approval as "substantive equivalents" to standard food crops with a 90 day scientific trials, feeding rats a diet that includes a percentage of the GMO. Is this the duration of the testing cycle--three months--for GMO crops enter the market as foodstuff?

Submitted by: T.Brown


Expert response from GMOAnswers Admin_1

Friday, 13/12/2013 13:13

You are correct that a feeding study is part of the safety assessment process for new biotech products. However, it is just one part of a comprehensive process. From initial concept to commercialization—which can take up to 13 years—numerous studies are conducted to support development and registration of new biotech products. During the regulatory science phase alone, more than 50 studies on food, feed and environmental safety are conducted.


The overall goal of the biotech safety assessment process is to determine whether the GM plant is, in essence, no different from a non-GM plant, with the knowledge that the non-GM plant has an established history of safe consumption. As you indicated, this was originally called “substantial equivalence” when it was proposed by international scientific authorities, including the World Health Organization, but today is more commonly referred to as the comparative approach. 


One of the most important parts of the biotech safety assessment is composition testing. In these types of studies, a GM corn plant will be grown in the field along with non-GM plants and the grain will be harvested. The grain is then subjected to analytical chemistry testing to determine the concentration of the individual components—components that we know are there. The concentrations of the different components are then compared between the GM and the non-GM corn plants. There is usually some variability in the concentrations of some of the different components, but that is nearly always observed in crops bred with traditional methods, too. Therefore, the historic concentrations from non-GM crops are available at an open-access website for further comparison. These methods have been very effective in demonstrating that GM technology does not introduce composition variability and that the grains obtained from these plants are “substantially equivalent” to those obtained from non-GM crops.


Ninety-day feeding studies in rats are common practice across many industries, including human pharmaceuticals, chemicals, etc. The 90-day rat-feeding studies for biotech safety assessment have been conducted to assess the possibility that unintended changes could have occurred during the development process that may not have been detected in the chemical analysis. To date, no adverse effects associated with consuming diets containing GM grain have been observed in any of these studies.