I know there is great concern over how genetically modified crops
could affect people. Does any scientific evidence exist that this has
happened?

Hi curlytina, and thanks for your question.

There has been a great deal of debate, as you know, regarding GMOs and
potential adverse health effects.  You can find an excellent
discussion of these issues, as well as numerous specific examples, in
this recent article from George Mason University:

Bakshi, A. Potential Adverse Health Effects of Genetically Modified
Crops. Journal of Toxicology and Environmental Health Part B: Critical
Reviews, Volume 6, Number 3 / May-June 2003, pp. 211-226

http://www.lib.cau.edu.cn/zjy/a141.pdf


This article contains both a general overview of the concerns about
GMOs as well as specific examples of adverse reactions along with some
background on the entities (corporations, etc.) involved.  The article
goes on to discuss the specific mechanisms believed to be responsible
for each specific type of adverse reaction.  Overall, the scientific
community is uncertain about the long term effects of GMOs in the
environment:

"But genetic engineering of crops is a new technology in its embryonic
stages. There are many other risks that have not been identified.
Scientists still have an incomplete understanding of physiology,
genetics, and nutritional value of genetically engineered crops, which
leads to the inability to predict
everything that can go wrong. It is essential to list any and all
concerns about commercializing genetically modified food. Scientists
still do not know enough about the way genes operate and interact in
genetically engineered organisms to be confident of what the outcome
of any modification will be. There is considerable scientific
uncertainty about what the immediate or long-term effects will be of
placing genetically modified foods into the food chain (Union of
Concerned Scientists, 2000)."

There is a long list of references included at the end of the article
for further reading.

___________

You can find a broader overview of the current situation regarding
GMOs in this article, from Drexel:
http://www.pages.drexel.edu/~ls39/peer_review/Myhr.pdf

This article, from Jules Pretty at the University of Essex, examines
the risks and benefits of GMOs:
http://oregonstate.edu/instruct/bi430-fs430/Documents-2004/1B-STATUS/Environ_Conserv_emergence%20of%20GE%20in%20world%20ag.pdf


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I hope this information is helpful.  Please feel free to request any
clarification prior to rating.

Best,

      -welte-ga



============
Search Terms:
(on Google Scholar)
scholar.google.com

genetically modified crops  "health risk" [search limited to 2001 to 2006]
http://scholar.google.com/scholar?q=genetically+modified+crops++%22health+~risk%22&hl=en&lr=&safe=off&as_ylo=2001&as_yhi=2006&start=30&sa=N

I would have appreciated either a few more sources or some summaries
of the particular cases, but this is a good start.  Thank you.