81% of approved GMOs not studied for detailed health effects
A group of researchers set out to see how much evidence there is for the safety of crops containing the most common GM genes – for insect resistance and herbicide tolerance – for animals that eat them. They focused on histopathological investigations of the digestive tract in rats, since this would be the main target organ of any new toxic proteins produced by the GM process.
The researchers found that of 47 crop varieties approved by government regulators for animal or human consumption, there were peer-reviewed published studies for only 9. They could find no studies whatsoever for the other 38 approved varieties. This means that they could not find any published histopathology studies for 81% of approved GM crop varieties. What is more, the studies that were carried out were poorly conducted or reported.
The researchers concluded, "There is a lack of evidence to prove that these crop varieties are safe to eat."
1. Does eating GM crops harm the digestive tracts of rats? – Clear English summary
2. GM crops and the rat digestive tract: A critical review – Study abstract
1. Does eating GM crops harm the digestive tracts of rats?
This is a briefing about a new, peer-reviewed scientific paper titled: GM crops and the rat digestive tract: A critical review, by Irena Zdziarski, Dr John Edwards, Dr Judy Carman and Dr Julie Haynes*. The paper is a review done by researchers at the University of Adelaide, Flinders University and the Institute of Health and Environmental Research, all based in South Australia. The paper reviewed published studies where the health of rats was assessed after the rats were fed certain GM crops.
2. GM crops and the rat digestive tract: A critical review
The aim of this review is to examine the relationship between genetically modified (GM) crops and health, based on histopathological investigations of the digestive tract in rats. We reviewed published long-term feeding studies of crops containing one or more of three specific traits: herbicide tolerance via the EPSPS gene and insect resistance via cry1Ab or cry3Bb1 genes. These genes are commonly found in commercialised GM crops. Our search found 21 studies for nine (19%) out of the 47 crops approved for human and/or animal consumption. We could find no studies on the other 38 (81%) approved crops. Fourteen out of the 21 studies (67%) were general health assessments of the GM crop on rat health. Most of these studies (76%) were performed after the crop had been approved for human and/or animal consumption, with half of these being published at least nine years after approval. Our review also discovered an inconsistency in methodology and a lack of defined criteria for outcomes that would be considered toxicologically or pathologically significant. In addition, there was a lack of transparency in the methods and results, which made comparisons between the studies difficult. The evidence reviewed here demonstrates an incomplete picture regarding the toxicity (and safety) of GM products consumed by humans and animals. Therefore, each GM product should be assessed on merit, with appropriate studies performed to indicate the level of safety associated with them. Detailed guidelines should be developed which will allow for the generation of comparable and reproducible studies. This will establish a foundation for evidence-based guidelines, to better determine if GM food is safe for human and animal consumption.