On Sun, 03 Aug 2003 09:13:56 +1000, Terry Collins wrote:

Apparently not the case. There have been posts for a few years from the
USA that this stuff leaches the chemicals all the times. I vaguly
remeber some enquiry in Australia into these claims being announced.

Quote from this CSIRO document here, Read the crops & mulch part
http://www.ffp.csiro.au/wft/wpc/ccafact1.html

Leaching

Nearly all the CCA fixed within timber remains there over its lifetime of
service; if it did not, the wood would rot and fail in much less than the 30-50
year period for which it is often guaranteed. However, a small amount of
leaching inevitably occurs. This can show up in small rises in arsenic levels in
the soil close to posts and poles; studies have found levels return to normal
within about 100 mm of posts and 100-200 mm of poles. Simple precautions, such
as those described below, can be taken to minimise any perceived risks from the
leaching.

Crops
A number of studies have shown that CCA is not absorbed into above-ground food
crops such as grapes, tomatoes and cucumber. There are, however, some reports of
a slight increase in arsenic content in root crops such as carrots and beets
grown against treated timber, although the arsenic is in a safe organic form and
most of it is removed with peeling. Any possible concern can be eliminated by
growing these vegetables more than 100 mm from treated-timber garden edgings, or
by lining the edgings with plastic. This has the additional useful effect of
reducing soil contact with the wood, which could further extend the wood's life.

Mulch
Use of treated timber - sawdust or chips - as mulch is not recommended because
of uncertainty about where the CCA will end up in the long term. Also,
Australian Standards have low tolerances for heavy metals in mulch, and these
may be exceeded with the addition of CCA-treated residues. However, small
amounts in the soil appear to be of minor concern. Interestingly, one study
found soil with CCA-treated sawdust mixed in as an amendment gave higher yields
of lettuce and beetroot than soil without sawdust or with untreated sawdust.
Sawdust increased the soil's water-holding capacity, and this effect lasted
longer with treated sawdust because of its slower degradation.



Quote from this CSIRO document here
http://www.ffp.csiro.au/wft/wpc/ccafact2.html#13

Disposal of treated wood

Currently, small volumes of CCA-treated timber wastes or off-cuts from domestic
or residential uses should be disposed of through normal waste collection
services. Trade or industrial users with large quantities of treated wood waste
(more than 0.5 tonnes per month) may require additional approvals; check with
local and state authorities in these cases. Sometimes it will be possible to
reuse treated wood in another application.

CCA-treated timber must not be burned in barbeques, fireplaces or wood-burning
stoves, or in any confined space, as toxic fumes and residues may be produced.



Quote from this CSIRO document here
http://www.ffp.csiro.au/wft/wpc/ccafact2.html#12

Some safety tips

Painting sawn CCA-treated timber has long been recommended as a way of reducing
warping and checking. The US Environmental Protection Agency has suggested that
it may also reduce the risk of exposure to any arsenic that may be present on
the wood surface.

When constructing playground equipment, the treated timber, especially the ends,
should be hosed and gently scrubbed. The sawdust and solid wastes produced
during construction must be collected for disposal.

None of the elements of CCA should move from the logs into the dry indoor
environment of a CCA-treated log house. However, some wood fibres may dislodge
over time. These can be swept up or vacuumed, but if this sends dust into the
air a dust mask should be worn. Indoor painting will seal and bind most loose
surface fibres.

Particular caution is needed if fighting a fire in CCA-treated timber, because
of the arsine gas liberated. Breathing apparatus may be required. CCA-treated
timber tends to smoulder longer than untreated timber, a feature called
'afterglow'.

Healthy sanding

Red :-)