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International Debate on Biosafety of Genetically Modified Crops:
Scientific Review on Several Cases of Debate |
| Jia Shirong Jin Wujun |
| (Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China) |
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Abstract Abstract: There were several cases of international debates on genetically modified crops: (1) Dr. Pusztai in 1998 claimed that genetically modified potato with snowdrop gna gene inserted had an adverse effect on the health of rat after feeding test. In the following year the Royal Society of UK conducted a thorough pure review on this issue. The conclusion indicated that the Pusztai's results were incorrect in many aspects, such as the experiment design, the execution and the statistics analysis etc. And no such an adverse effect should be drawn from it. (2) In 1999, 《Nature》 published a paper by one group from Cornell University in which they reported that the larvae of monarch butterfly were killed by the pollen of Bt corn on milkweeds. Subsequent laboratory and field studies have concluded that the larvae are not likely to be harmed by pollen of Bt corn in natural conditions. The fact is that the majority of pollens move only a short distance away from cornfield and cornfield typically contains a lower density of weeds, including milkweeds. The decline of population density of monarch butterfly is mainly caused by the over use of pesticides and the environmental changes occurred in Mexico. (3) In 1998, volunteer canola resistant to three herbicides was documented in a producer's field in Northern Alberta, Canada, which was then so called "super weeds" by activists. In fact, "super weeds" is not a scientific term and there is no such a thing existed in the nature as volunteer resistant to three herbicides can be killed by spray of herbicide 2,4-D. (4) In November 2001, Quist and Chapela published a paper on 《Nature》 claimed that DNA sequences similar to CaMV35S promoter and adh1 gene used in Bt 11 were found in the samples of maize landraces collected from Oaxaca, Mexico. It was then so called "gene pollution or gene contamination" by Green Peace. However, subsequent scientific analysis demonstrated that the sequence of 35S promoter was artifacts and the sequence of adh1 was the adh1-F that was a native gene in maize but not the transgenic gene of adh1-S used in Bt 11. CIMMYT has tested samples recently collected in Mexico fields and in their gene bank. The results showed that none of them contained 35S promoter sequence. (5) In June 2002, the Green Peace published a report saying that "Bt cotton damaged environment in China", which was totally flawed and misinterpreted. The positive consequences of Bt cotton grown in China have not been cited in Green Peace's report. The fact is, as a result of application of Bt cotton, the amount of pesticides used for control of cotton bollworm has been dramatically reduced by 70~80 percent. The population size of predators and the diversity of arthropods in Bt cotton field have increased. Because of less pesticides were used in the early stage of cotton growing season, the natural enemies of cotton aphids were significantly increased that resulted in a dramatic reduction of aphid population by 443~1546 folds in Bt cotton field comparing with that of in non-Bt cotton field. Monitoring bollworm population nationwide in cotton growing area has shownthat none of them have developed resistance to Bt powder or Bt cotton to date. The migration behavior of bollworm, the inheritance of insect resistance to Bt controlled by an incomplete recessive gene, the existing of "natural refugees" by multiple cropping systems in Northern China and the application of transgenic cotton with double genes (Bt/CpTI ), all of these have the functions in delay the development of resistance in bollworm population to Bt cotton. In conclusion, basically the nature of international debate on biosafety of genetically modified crops is not a pure scientific issue rather it is related to the economic and trade considerations.
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Received: 01 January 1900
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