You might be interested in reading this answer by Bruce Chassy, Professor Emeritus of Food Safety and Nutritional Sciences, Department of Food Science and Human Nutrition at the University of Illinois, Urban-Champaign, about using science to make deductions about the probable future: http://gmoanswers.com/ask/are-there-any-long-term-30-years-studies-done-full-spectrum-ecological-impact-transgenic-gmo. An excerpt is included below.
Science is the best system available for making extrapolations to what is most probable in the future. Climate-change science is a good example. No, the world hasn’t gotten as warm as it is going to get in 50 years, but scientists are confident that if current trends continue, it will get much warmer. That’s using science to predict the future. Can science predict with 100% certainty? Absolutely not! We all have different personalities. To some of us a glass is half full, to other it is half empty. When we think about change, as for example adopting GM crops, some of us see risks, and other of us see benefits. That’s just human nature and we are fortunate that the risk-averse among us help us to look before we leap into a bad situation.
I can’t resist pointing out that long-term tests have never been required for any new seed variety or crop. GM crops are the only crops to be subjected to pre-market safety assessment in spite of the fact that crops produced using other methods of genetic modification having identical new traits are not tested before their use. It makes absolutely no scientific sense to single out GM crops for pre-market testing while ignoring others that are made using older less exact methods. Of course we don’t require pre-market testing of crops because crop breeding has over many years and thousands of new varieties introduced proven to be a safe science. And there’s no scientific reason to believe that GM crops are any different with regard to safety in spite of the well-financed and professionally-orchestrated global campaign aimed at making consumers believe that GM crops are inherently different, inherently unsafe.
Additionally, a response from Peter Davies, Professor of Plant Physiology and International Professor of Plant Biology, Cornell University, Ithaca New York, states:
GM crops are not expected to present any new food risk, as the changes are simply in a molecules (protein and DNA) that have been in our diet for ever, and the small quantity of added material is degraded in our gut in exactly the same way as has always occurred. There has been very extensive safety testing carried out in many countries around the world, and GM-crops have been found to be no different from non GM-crops of the same species in terms of safety as food, or in environmental effects.
The European Union has said: “The main conclusion to be drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of research and involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not per se more risky than conventional plant breeding technologies” ("A decade of EU-funded GMO research," Directorate-General for Research and Innovation, European Union, 2010).
A multitude of studies by academic scientists have been conducted to assess the food safety of GM crops. Summing them up, the American Association for the Advancement of Science recently said: “The science is quite clear: crop improvement by the modern molecular techniques of biotechnology is safe” (http://www.aaas.org/news/releases/2012/media/AAAS_GM_statement.pdf).
After sixteen years of consumption by billions of livestock, pets and humans, there has been no cases of allergy, cancer or death, or indication that the GMOs are of any health concern. Claims of effects have been found to be anecdotal and without merit, and are rejected by the overwhelming majority of scientists worldwide.
Should any new information or studies be discovered indicating adverse information about a GM product on the market, the law requires that such information be brought to the FDA, which regulates the safety of all foods and food products – including from GM plants.