>
> "Imidacloprid is considered to have a low toxicity to fish. Because
> imidacloprid breaks down rapidly in water and sunlight (3 hour half-life),
> there is little chance, even if a large amount was applied directly to
> water, that it would impact fish. Imidacloprid, unlike toxins such as
> mercury, does not bioaccumulate and thus is rapidly excreted."
>

You have the above in quotes, Randy, but do not state the source.  The
three hour half life (Wamhoff, Moza) and quoted in a document you might be
using from California:

 http://www.cdpr.ca.gov/docs/emon/pubs/fatememo/imid.pdf

is NOT suitable to the Darling River that Peter is writing about.  The
Darling River is a big shallow muddy river when there is a flooding event,
such as when the fish kills happened.  The 3 hour sunlight aqueous half
life is only at the surface where sunlight can penetrate the muddy water.
The majority of the volume of the river is not at this surface.  And
although imidacloprid is not highly toxic to fish, it has a LC50 to some
crustacean and mollusc larva that is much lower than that for bees.

By the way, the document from your California dept of Pest Management gives
a range of soil half life for Imidacloprid up to a max figure of 229 days
in the link above.  But that was posted in 1995, five years after the
emergency registration of imidacloprid in PEI, and the soil study done for
that registration on PEI showed a half life up to 455 days.  That is twice
the max figure in that document, a substantial error.  And there is the
trust issue that Peter D and Juanse are posting about.  (I am talking from
the point of view of someone who HAS sat at the table with people from
Bayer and the regulatory agencies and the university scientists doing the
studies, several times).  The 455 days is a real figure.  You will not get
anyone from Bayer to dispute that.   They paid an independent company to do
the soil study and submitted it to our pest management regulatory agency.
But it does not show up in published literature (Bayer naturally does not
want it to) and when I submitted an access to information request to the
Canadian government for the soil study report I was told that because Bayer
had paid for it that it was not in the public domain, despite it being
necessary for registration.  That is not the sort of thing that inspires
trust in the system.  If I had not seen the figure by accident at one of
those meetings I would never have been able to know about it.  And
apparently your Calif. dept of pest management does not know about it.  So
how trustworthy is the system?

Stan

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