The first study that generally assessed the long-term effect of GM feed on rat health was in 2002 (Wang et al., 2002). It investigated a GM rice (KMD1) that is approved for commercial use only in China. This approval was granted seven Selleckchem LY294002 years after the Wang et al. (2002) study was published (Chen et al., 2011). Two other studies also investigated this crop (Kroghsbo et al., 2008 and Schrøder et al., 2007), both of which were published prior to the approval. The

remaining 16 (76%) published studies found in this review were published after the crops had been approved for human and/or animal consumption. Half of these were performed at least nine years after the approval was granted. Five studies based their methodology on the Organisation for Economic Cooperation and Development (OECD) guidelines for the testing of chemicals — OECD Guideline 408: repeated dose 90 day oral toxicity Selleck Epigenetics Compound Library study (OECD (Organisation for Economic Co-operation and Development), 1981 and OECD (Organisation for Economic Co-operation and Development), 1998). Fourteen studies indicated that the digestive tract was investigated histopathologically,

but no details were given as to what analyses were performed. The only details most often provided were that tissue samples were processed, paraffin embedded, and sections were cut and stained with haematoxylin and eosin (H&E). Sections were then assessed using light microscopy (LM). Seralini et al. (2012) indicated that sections were stained with HES, but failed to specify whether this abbreviation meant haematoxylin and eosin, haematoxylin eosin safran/saffron or haematoxylin erythrosine saffron stain. Seralini et al. (2012) also indicated that

if any tumours were observed, they were processed for transmission electron microscopy (TEM). There was no mention if tumours were observed in the GI tract. Six of the studies indicate that a pathologist or veterinary pathologist performed the histopathological analysis. Five studies provided Phenylethanolamine N-methyltransferase some form of results of their analyses, whilst most limited their results section to a statement that overall there were no treatment-related or diagnostically-significant observations. Overall, all the studies examining the GI tract concluded that there were no toxicological or pathological changes observed that could be related to feeding GM crops to rats. The digestive tract is the first site of contact with the body of any ingested food. Therefore, if a novel food is toxic to the body, signs of toxicity may be present in the GI tract. Often these changes may only be detectable by histopathological analysis and not macroscopic observations (Morini and Grandi, 2010). Whilst 14 out of the 21 studies reviewed (67%) indicated that organs of the digestive tract were collected for histopathological examination, none of the methods sections in these publications included any details as to the nature of the histopathological examination.