This is a common question topic and has been discussed a number of times on GMO Answers. We would like to share a couple of those responses with you.
You might be interested in a response from Dr. Denneal Jamison-McClung, associate director for the UC Davis Biotechnology Program, in which she addresses the question “How can you be sure that GMO foods won’t affect human health long-term?” While an excerpt is below, her full response is available here.
“…Currently approved GM crops developed through specific genetic additions or subtractions are as safe as conventional and organic crops developed via random genetic shuffling. Most people do not realize that plant breeders have been randomly altering and admixing plant genomes for centuries. Techniques using chemicals and radiation to break plant DNA and induce mutations have been used to develop many conventional and organic crops. Whether using traditional approaches or genetic engineering, the goal of plant scientists is to develop crops with new and agriculturally useful traits. Humans have been changing plant genomes for generations—we just have new, more precise, tools…Given that we’ve been genetically modifying plants for millennia, using one approach or another, we should frame this question in terms of relative risks: How ‘sure’ can we expect to be when it comes to long-term health impacts of GMO foods? Like most things in life (except death and taxes, as the saying goes…), 100% certainty is not possible or reasonable to require. However, safe use of GMO foods since 1996, coupled with our knowledge of human and plant physiology, points to long-term safe use of genetic engineering as a plant breeding tool set in agriculture.”
Also, Dr. Bruce Chassy, professor emeritus of Food Safety and Nutritional Sciences at the University of Illinois at Urbana-Champaign, answered a question about long-term health studies—specifically, if any studies were available that were 30-plus years in duration. An excerpt of his insight to the question is below, and the full response is available here:
“The short answer to this question is NO, there are no 30+ year studies done on GM crops. The first plant transformation was to produce a GM plant was reported in 1982, which was only 31 years ago. Before a GM plant can be approved by the USDA, its potential ecological impact must be fully evaluated. The question appears to be asking if full-spectrum ecological studies are done for every organism, and, by inference, every conceivable situation. It is simply impossible to test all organisms in all situations. Accordingly, scientists select key nontarget species and indicator organisms that serve as surrogates for different classes of environmental organisms, from microbes to whole animals, and typically at a minimum evaluate ecological effects in at least three agro-ecosystems on three continents for at least three growing seasons—sometimes more. Field tests are always performed with and without the normally used pesticides and herbicides since that’s just good experimental design. Scientists and regulators have concluded that this provides a clear enough view of how a crop will impact the environment. As an additional safeguard, a plan for post-market agro-ecological monitoring is also put in place to ensure that any unexpected adverse effects are detected. If any post-market adverse effect is detected, systems for management and mitigation can be put in place, or the crop can be withdrawn from the market. Fearmongers who are opposed to GM crops always forecast ecological doom from some unforeseen impact, when in fact crops are grown season by season and if an adverse impact occurs, the use of the crop can be discontinued. This is a peculiar concern, since irreversible ecological disasters caused by domesticated crops have not to date been scientifically documented. The resilience of natural ecosystems would most likely allow affected ecosystems to quickly return to their prior state. That said, GM crops have been planted on more than 2 billion hectares by more than 17 million farmers over 17 years in about 30 countries, with no adverse ecological impacts observed. Fair to say, that’s a pretty robust long-term study!”
Please let us know if this answers your question.