Gilles-Éric Séralini’s latest study on GMOs–“Laboratory Rodent Diets Contain Toxic Levels of Environmental Contaminants: Implications for Regulatory Tests”–was published on PLOS ONE on July 2, 2015 more than two weeks after its originally scheduled release.

GLP has an analysis of the latest Séralini study here.

GLP has a profile of Séralini and his research here.

Journalists had been supplied with an embargoed version of the original paper in mid June. The final version contains two significant changes.

Séralini had not disclosed that his laboratory and the professor himself has received significant funding from Sevene Pharma, a French company that promotes “cures” using homeopathy, which mainstream scientists consider pseudo-science. Sevene sells homeopathic remedies but is also paying Séralini to research atrazine and glyphosate risks. Sevene markets “detoxification” homeopathy products to treat the alleged toxic effects of glyphosate and atrazine “contamination”, which is the focus of Séralini’s research, a clear conflict of interest the professor has apparently been forced by PLOS to now acknowledge.

Séralini has been a long time consultant for Sevene. According to an article on the French professor (published in French here, but translated and excerpted here by geneticist David Tribe), he also spends a significant part of his time promoting so-called detoxification products, for example at a training seminar organised by Corinne Lepage’s CRIIGEN, with lectures organized by Sevene and at symposiums on alternative medicine, some sponsored by Sevene. Séralini’s research team includes a former director from Sevene. A translation of the French article–“The “dark side” of Professor Séralini–is available here.

The final PLOS version of the study also eliminated a section from the abstract:

The high background rate of pathologies in laboratory rodents could be due to die- tary contaminants. This invalidates the use of external controls (historical data) in regulatory tests, consisting of comparisons of toxicological effects to control rats from other experi- ments, because these control rats are fed different mixtures of pollutants. This also ques- tions the use of 50 rats per group in carcinogenicity studies to increase the statistical power lost due to the elevated pathological background.

Scientists react

Two organizations, the Science Media Centre in the UK and Washington, DC based GENeS–Genetic Expert News Service–an independent, foundation funded NGO–solicit expert opinions from independent researchers on breaking genetics stories. Both organizations have posted analyses on their respective websites. The GLP summarize a few key reactions here, but we urge readers to visit those websites directly for extended comments.

GENeS

Dr. Richard E. Goodman, Research Professor in the Food Allergy Research and Resource Program, University of Nebraska (webpage):

The authors are using a controversial method of estimating cumulative risks (Hazard Quotients) of minor contaminants in animal feeds that have not been validated to demonstrate realistic risks, with biological proof of harm at levels of contamination that the authors found in this PLoS ONE study. As far as I know, there have not been publications demonstrating that the method of cumulative hazard assessment, even though referenced by a paper by the US EPA and one in the EFSA Journal (11:3313), have suggested this approach might be useful for understanding risks of mixtures of chemical toxicants including pesticides, dioxins and heavy metals have accurately predicted risks or outcomes. The fact is that no studies I am aware of, other than the authors’ previous retracted study in Food and Chemical Toxicology in 2012 on NK603 maize and glyphosate, has shown high levels of tumors, cancers or other deleterious effects in control animals fed normal commercial rodent diets. The authors have not cited published studies that have shown high levels of adverse effects in control animals fed commercial rodent diets. It seems the authors are trying to prove that their earlier reported tests with high tumor incidence in the 2012 study was due to “incidental contamination of control diets” rather than the genetic strain of rats used in their 2 year study. Or that they want to invalidate the safety tests on many GM crops. Yet the same tests and lab chow has been used safely to demonstrate convincing risk or safety of a number of pharmaceuticals, pesticides and other compounds.

Dr. Frédéric Y. Bois, Professor at Sorbonne UTC, and Research Director at L’Institut National de l’Environnement Industriel et des Risques (INERIS)(webpage):

Not too surprisingly, rat diet, like most of ours by the way, is contaminated with those chemicals. It would actually be interesting to compare those results with the producers’ records. Whether the exposed rats are likely to suffer serious damage from such exposures is not clear though. The hazard indexes computed by the authors use acceptable daily intakes (ADI) calculated for humans. Those do not really apply to rats, because safety factors are used in their derivations to specifically protect humans (assumed to be more susceptible than animals), and among humans infants etc. Furthermore the hazard indexes for various chemicals were summed to get an estimate of the effect of the multiple exposures. Using hazard indexes and summing them maybe a reasonable conservative procedure for protecting human public health. However, when assessing the actual impact of food contaminants on the health of lab animals (which is a matter of scientific precision, not of rat health protection) they are likely to overestimate the risks. The question also of the number of chemicals whose safety evaluation has been biased by the presence of food contaminants in lab animal diets needs to be addressed with precaution, without jumping too fast to conclusions. At least the authors should be congratulated for tackling an interesting question, which, by the way, also extends to the analysis of epidemiological cohorts.

Dr. Carl Winter, Cooperative Extension Food Toxicologist, University of California, Davis (webpage):

The authors contend that since the maximum dietary intake of the pesticide pirimiphos-methyl in seven of the diets exceeds the Acceptable Daily Intake, that animals fed such diets are being fed toxic levels of pirimiphos-methyl. This conclusion is not supported for two reasons 1) The maximum dietary intake represents an exaggeration of the true dietary intake. 2) (More important) Comparing maximum dietary intake with the Acceptable Daily Intake is not appropriate to demonstrate risk. A more appropriate comparison would be the No Observed Effect Level (NOEL) from long-term animal toxicology studies, which represents the maximum amount given to laboratory animals on a daily basis that does NOT cause any noticeable toxicity. For all of the other seven pesticides detected, exposure at the exaggerated maximum dietary intake level was still below the ADI levels, (commonly 100 times lower than NOEL levels from animal studies), so it is difficult to make a valid case as to how such exposures would cause effects in the animals consuming feed containing pesticide residues.

Science Media Centre