Monsanto’s efforts to dismiss new evidence linking its genetically modified (GM) corn to tumors has been thoroughly debunked in a public briefing by the food sustainability nonprofit Earth Open Source.
“NK603 must be immediately withdrawn from the market and all GMOs must be subjected to long-term testing,” the briefing concludes.
In a two-year study, a team of French researchers led by Professor Gilles-Eric Seralini found that rats fed Monsanto’s “Roundup Ready” corn developed significantly more tumors than a control group not fed GM corn. The rats fed a GM diet also developed tumors that appeared earlier and behaved more aggressively, and died sooner than rats in the control group.
The study found similar effects in rats exposed to Roundup herbicide at levels currently considered safe by most regulators.
“Roundup Ready” crops have been engineered for resistance to Monsanto’s top-selling herbicide glyphosate, marketed under the trade name Roundup. In the scientific literature, Roundup Ready corn is also known as NK603.
Monsanto’s faulty defenses
Responding to the study, Monsanto claimed that the findings were not significant because tumor rates in the rats fed GM corn were “within historical norms for this strain of laboratory rats, which is known for a high incidence of tumors.” In other words, the company has claimed that the rats developed tumors simply because of their genetics, and that the tumor rates seen in the rats fed GM corn were similar to tumor rates in rats not fed GM corn in other studies.
In response to Monsanto’s “tumor prone rats” argument, the briefing notes that while tumors did in fact occur in both groups of rats, they were both more common and more aggressive in the experimental group – and it is the difference between the two groups that is relevant for scientific study.
“This is a basic principle of science and it is worrying that attempts are being made by pro-GM lobbyists to override it in the interests of keeping the products of powerful multinational biotechnology companies on the market,” the briefing reads.
The briefing also debunks Monsanto’s “historical data” argument. First of all, the historical tumor data cited by Monsanto actually comes from a completely different strain of rats (Charles River Labs SD rats) than those used in the study (Harlan SD rats). In fact, the researchers did compare their findings to historical tumor rates in Harlan SD rats, and found that all their results remained statistically significant. For example, the rate of tumors in rats fed GM corn was three times higher than the historical average tumor rates for the same strain of rats.
The briefing further notes that the very idea of using “historical data” to dismiss statistically significant findings is shoddy science, and the technique is rejected by serious scientists. Any legitimate scientific study includes a control group that is tested at the same time as the experimental group, because this is the best way to actually control as many variables as possible and make sure any differences observed are due to the variable being tested (in this case, consumption of GM corn). Rats in other studies may have been fed different diets, been at different phases of their life cycles, been exposed to other environmental pollutants, had a different genetic background, or been exposed to any number of other potentially relevant factors.
“The use of historical control data is an unscientific strategy used by industry and some regulators to dismiss statistically significant findings of toxicity in … studies intended to evaluate safety of pesticides, chemicals, and GMOs,” the briefing notes.