Abstract: OBJECTIVE: The study investigated toxic effects of sub-chronic oral exposures for 90 days in rats to genetically modified (GM) corn with insect-resistant gene cry1Ab and cry3Bb, herbicide-resistant gene cp4epsps, high vitamin gene ZmHPT and ZmTMT. METHODS: 6-week-old Westar rats, half males and half females, were randomly divided into 7 groups with 20 per group according to weight:basic feed control group,non-GM corn groups (low-,medium- and high-doses),GM corn experimental groups (low-, medium- and high-doses). Rats were fed the different corns for 90 consecutive days. Then,they were observed for changes in body weight, food intake, blood biochemical indicators, organ coefficients and pathological features. RESULTS: Rats in each dose group grew normally during the test cycle. The body weight, food intake, blood biochemical indexes, organ coefficients of some GM corn and non-GM corn groups were significantly different from those in the control animals (P < 0.05). In addition, the differences were also significantly different between the GM corn compared with the non-GM corn groups (P < 0.05). However, no significant abnormalities were found in the pathology examinations of some main organ tissues. CONCLUSION: The experimental results show that sub-chronic exposure to the genetically modified corns did not lead to obvious pathological changes in rats.

Key words: genetically modified corn, subchronic toxicity, rats, feeding 90 days test