Trevor wrote:
"The Invalid" wrote in message
...
On Sun, 10 Sep 2006 21:01:46 +0100, "Trevor"
wrote:

As my spinach is growing away nicely in the poly tunnel with it's roots
touching the tannalised timber sides of the bed , it occured to me - is
this
safe?


I have a deep bed for some veg which uses Tannalised timber for the
sides with no problems

Any idea what chemicals they use in the process? I don't think they use
ARSENIC any more!

Unless I'm out of date, they still do. Tanalised timber is treated with
copper, chromium, and arsenic compounds. It's meant to be done in such
a way as to minimise leaching: it seems the main thing, assuming the
correct proprietary solution is used, is a long enough period of
drying, which fixes the compounds. One study, from New Zealand,
available on the Net reports some uptake of arsenic by spinach grown in
the kind of bed you describe, but according to that study it was below
the recommended level -- you can make up your own mind about that! I
don't think I'd be worried, but the paper's at:
http://72.14.221.104/search?q=cache:...&cd=8&ie=UTF-8
or:
http://tinyurl.com/hgka8

I think we've suggested before that, if one's worried, it would be a
good idea to line raised beds with plastic sheeting of some kind to
stop any soil contact with treated timber.

--
Mike.