Although May 2014 will mark the 20th anniversary of the U.S. FDA’s approval for and Calgene’s market launch of the world’s first commercially available genetically engineered (GE) whole food, the Flavr SavrTM tomato, it’s amazing how relevant that GE tomato remains in today’s ongoing debate over use of the powerful technology used to create it. Take the recent case of the long-term study by Séralini and colleagues of rats fed Monsanto’s NK603 GE corn, for example.
Just as Séralini’s “inconclusive” (preliminary?) results suggest that an unintended change might have occurred in NK603 corn, one particular variety of Flavr Savr tomato tested for unintended changes back in early 1992 initially appeared to have one as well: variety CR3-623 apparently caused lesions to form in the stomachs of rats while rats fed other Flavr Savr tomato varieties or control tomatoes did not.
It was Calgene’s response to those unexpected, unintended results that is relevant to today’s ongoing debate over GE foods.
Calgene immediately initiated additional experiments on the offending tomato variety. The subsequent studies replicated the original experiment, tested for a dosage effect (the hypothesis being that if the lesions were really related to variety CR3-623, then feeding rats twice the original amount of fruit should cause a corresponding increase in the number of stomach lesions formed), and carefully analyzed levels of toxins normally found in green tomatoes to determine whether elevated glycoalkaloid levels could have been responsible for the lesions. Basically, the scientists at Calgene responded to the unexpected results with more science in an effort to get to the bottom of the issue.
Similarly, a scientific response was launched after publication in 1999 of “Transgenic Pollen Harms Monarch Larvae” in the journal Nature. Stakeholders from the biotech industry, academia and various non-profit organizations gathered together and planned the scientific investigations to determine whether the lab results published in Nature could be relevant to monarch larvae in and around the hundreds of thousands of acres in the United States where GE corn plants engineered to express proteins like the one that harmed monarch larvae in the lab were already growing.
A scientific study, “Investigation of Human Health Effects Associated with Potential Exposure to Genetically Modified Corn,” was also conducted by the U.S. Centers for Disease Control and Prevention (CDC) in the wake of the discovery in 2000 of contamination of human food products in U.S. grocery stores with StarLinkTM corn, a GE corn variety which had been EPA-approved only for animal consumption.
And more science is also the proper response to the results obtained by Séralini and his colleagues.
Séralini’s manuscript and raw data were scrutinized by the Editor-in-Chief of Food and Chemical Toxicology who “unequivocally…found no evidence of fraud or intentional misrepresentation of the data.” The journal deemed Séralini’s results “not incorrect” but “inconclusive” because “the number of animals in each study group and the particular strain” of rat used posed “cause for concern;” the paper was subsequently retracted.
Regardless of whether retraction was warranted…the proper scientific response to this scientific controversy is clear: Séralini’s experiments should be repeated using a different strain of rat and more animals in each study group.
And since the FDA informed Monsanto, after the company completed a voluntary consultation with the agency prior to its marketing of NK603 corn, that “it is Monsanto’s continued responsibility to ensure that foods marketed by the firm are safe [and] wholesome…”, it appears that it is Monsanto’s responsibility to make sure that conclusive evidence related to safety and wholesomeness is available in this matter related to NK603 corn.
What kind of results have follow-up studies of GE crops produced over the last two decades?
The field studies of Bt-expressing corn pollen, comprising four papers in Proceedings of the National Academy of Sciences U.S.A., largely exonerated the GE corn varieties that were commercially available at the time of posing risks to monarch butterfly larvae out in the real world. According to the USDA’s interpretation of these results, “monarch caterpillars have to be exposed to pollen levels greater than 1,000 grains/cm2 to show toxic effects” and “corn pollen levels on milkweed leaves were found to average only about 170 pollen grains/cm2 in corn fields.” However, one GE corn variety, Bt176, “was found to have some negative effects on monarch caterpillars with pollen concentrations of only 10 grains/cm2.” On a web page last modified 10/26/2017, USDA indicated that Bt176 “likely will be phased out by 2003.”
The CDC study of StarLink corn’s potential to cause allergies in humans did not “provide any evidence that the reactions that the affected people experienced [in 2000] were associated with hypersensitivity to the [GE] protein” produced in the StarLink corn. The study concluded, however, that “difficulties of this investigation highlight the importance of evaluating the allergic potential of genetically modified foods before they become available for human consumption.” And enough concern remained that, at the recommendation of the FDA, more than 4 million tests for the presence of the infamous GE StarLink protein were performed on 4 billion bushels of yellow corn at grain mills throughout the U.S. between 2000 and 2007.
After repeating our rat-feeding study at Calgene, lesions were again identified in the stomachs of rats fed tomato variety CR3-623; but stomach lesions were found in rats fed non-GE tomatoes too (see Table 1 in the FDA Agency Summary Memorandum on the Flavr Savr tomato) and FDA deemed the Flavr Savr tomato, including variety CR3-623, “as safe as other commonly consumed tomatoes.” My recollection is that Calgene did not commercialize Flavr Savr tomato variety CR3-623, but the company certainly could have if it had wanted to.
Whether long-term studies of rats fed NK603 will conclusively reveal any unintended, unexpected consequences of the genetic engineering process on that GE corn variety remains to be seen. But follow-up experiments to address this controversy should definitely be undertaken.
Hopefully, the appropriate experiments are already underway. If not, perhaps the FDA should ensure that those experiments are carried out. After all, if the regulatory system for GE crops in the U.S. is truly “science-based” as is often stated, conducting more science in order to get to the bottom of the NK603 corn controversy should be an automatic response.