Laboratory rodent diets contain broad range of environmental contaminants as well as genetically engineered plants

Scientists from France examine 13 samples from 9 countries

3 July 2015 / An investigation led by the French scientist Gilles-Eric Seralini has found a broad range of environmental contaminants such as pesticides, heavy metals and PCBs in feed used for laboratory animals such as rats and mice. The contaminants were detected in standard diets used for purposes such as raising the animals and feeding the control groups in toxicological studies. Some of the concentrations that were measured were above existing limits and the mixtures of contaminants could be said to be a health risk. Further, some of the diets were found to contain up to 50 percent of genetically engineered plants.

The samples were received from suppliers in nine countries representing five continents. The feed was analysed for traces of several hundred contaminants, some of which would only rarely be investigated for in the usual process of quality controls. Feed with a high level of contaminants can mask relevant effects in feeding studies when given to control groups, which means that potentially hazardous effects can remain undetected.

Laboratory rats in particular frequently suffer from so-called spontaneous tumours. The French scientists are warning that if the contaminants they found in the feed are ingested on a permanent basis they can influence the incidence of such tumours, and may lead to systematic errors in in the outcome of animal feeding studies.

The new publication also raises doubts in regard to the risk assessment of genetically engineered plants. These doubts have been added to by data presented by industry-based applicants for market authorisation in the EU. Testbiotech has often found remarks in the dossiers that the feed used for control group was contaminated with genetically engineered plants. Further, it has to be assumed that most laboratory animals are raised on diets containing genetically engineered plants even before the actual feeding study is started. Consequently, it can be expected that in many cases the health effects of genetically engineered plants will remain undetected.

After the first announcement of this study in the middle of June, several reactions were seen that show that the work of the team of Gilles-Eric Seralini is much more scrutinized than other scientists publishing in this area. Testbiotech is concerned that some of the criticism seems not to be interested in in the discussion of the scientific findings. Instead they seem to primarily target the credibility of the French scientists who are working independently from Agrochemical companies. These kind of reactions can substantially hamper meaningful scientific debates.