THE argument over the safety of genetically modified food was stoked up this
week as an OECD conference on the topic in Edinburgh heard conflicting evidence
on whether it harms rats. A big unpublished study from China says it does not,
while newly unearthed American findings from 1993 raise some fresh doubts.
Controversy arose in 1998 after claims by Arpad Pusztai, then at the Rowett
Research Institute in Aberdeen, that rats fed potatoes engineered to produce a
snowdrop protein suffered damage to their immune systems and changes in the size
of internal organs. Other scientists said his results were flawed and he was
suspended from the institute
(快猫短视频, 20 February 1999, p 4).
Now Zhang-Liang Chen of Beijing University has unveiled the results of over
40 government-funded experiments on hundreds of rats. He fed the rats raw sweet
peppers and tomatoes containing a gene from the cucumber mosaic virus, then
compared their internal organs, blood and sperm with controls. In no instance
did he find any significant differences in the GM-fed animals.
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鈥淲e did not see any problem,鈥� Chen told the Edinburgh conference. He
stresses, however, that his results do not prove or disprove Pusztai鈥檚 claims
because his experiments involved different genes in different vegetables.
The American evidence is buried within 40 000 pages of internal documents
released by the Food and Drug Administration (FDA) in response to a legal
challenge from groups campaigning against GM foods. Memos from 1993 reveal an
experiment in which 4 out of 20 female rats fed the first GM tomato, called
Flavr Savr, suffered 鈥済ross stomach lesions鈥�.
The company that produces Flavr Savr, Calgene of Davis, California, concluded
that the lesions were 鈥渋ncidental鈥� because they also occurred in rats not fed
Flavr Savr. The memos show, however, that some FDA scientists thought that there
was not enough information to come to this conclusion. It is not clear from the
documents whether later experiments resolved the issue.
James Maryanski of the FDA argued in Edinburgh that the memos show that
scientists were asking the right questions. 鈥淭heir views were taken into account
in our final policy,鈥� he says.