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Re: E-M:/ Fw: PESTICIDES LINKED TO LYMPHOMA



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Enviro-Mich message from Rane Curl <ranecurl@engin.umich.edu>
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On Fri, 18 May 2001, David Zaber wrote:

> Perhaps Dr. Curl didn't catch the rest of the press release which
> discussed the peer review process for this study.  Complaining that
> the anecdotal portion of the press release does not support the
> findings of the study is a bit, well, off the mark.  I strongly
> suggest that folks read the report before making conclusions regarding
> the suitability of the studies reviewed, etc.  

My point was that the snippet posted to this list was meaningless, so one
can well ask why it was posted. I reached and stated no conclusion about
the study itself, only about what was presented. Unbalanced reporting
does, of course, often present a biased interpretation, and not always
unintentionally.

> However, when it comes
> to cancer, if a chemical causes cancer in test animals, its a good bet
> that humans may be at risk.

It is not a "good bet", but it is at least suggestive. The proposition is
the basis for using the well known Ames test for mutagenicity, but the
best one can say is that "there is a good correlation between mutagen
strength and carcinogen strength in rodent studies"
(http://www.ilpi.com/msds/ref/amestest.html). It is quite inappropriate to
"ban" some very useful chemical from use solely on the basis of the Ames
test or even on the basis of tests on animal models. It is well known that
animals and humans respond differently to many chemicals, in regard to
carcinogenicity. (The saccharin controversy is still with us, even though
it does not give a positive Ames test result -
http://www.ultranet.com/~jkimball/BiologyPages/A/AmesTest.html).

I do agree that it is better to "err on the side of caution" (though the
people that reversed the EPA recommended 10 ppb limit on arsenic
apparently do not hold to that), but not to make categorical statements on
the basis of caution.

--Rane L. Curl



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