Pressurized timbers

**C* H* <c*@sentex.net>**

Apologies for jumping in late on this, but I wanted to check some
references and discovered my filing was even further behind than I
thought. I've been following the pressure-treat question for years. The
best places to get accurate, scientific information on the subject that
I've found are the websites of the Environmental Protection Agency (EPA) in
the U.S. and the Pest Management Regulatory Agency (PMRA) of Health Canada
in Canada. The two agencies are cooperating on a reevaluation of Chromated
Copper Arsenate (CCA) treated wood. It is a long, painfully slow process
and they have missed all their previously-announced completion dates. You
will have to wade through a lot of bureaucratese and chemical terms to get
the facts. The whole thing cries out for executive summaries. Here's a
short history of the recent events:
2001: Health Canada fact sheet says PMRA and EPA are cooperating to
reevaluate CCA. Target completion date: 2002.

CCA wood cannot be used in contact with drinking water, cannot be
burned. CCA solutions are not available to the general public, only
trained commercial or industrial users. Enhanced consumer information will
be implemented ASAP, target spring of 2002.
A Globe & Mail article says CCA has been banned in Switzerland, Vietnam and
Indonesia, and restricted in Japan, Denmark, Sweden, Germany, Australia and
New Zealand.
There are reports of a family burning CCA wood for heat who suffered
blackouts, seizures, hair loss, dead plants and fish. Also 22 cows killed
in Minnesota when a farmer spread ashes on a field where they grazed. Also
a scientist in California who says arsenic from CCA wood stunts plant
growth and turns leaves yellow.
2002: EPA announces on Feb. 12 a voluntary decision by industry to phase
out pressure treat containing arsenic in favour of new alternatives by Dec.
31, 2003. EPA will not allow CCA for residential use by Jan. 2004. New
labels will be required on all CCA products during 2003, specifying that no
use is allowed for residential uses after Dec. 31, 2003.
2003: In January there is a report in the Globe & Mail that an
environmental group has tested playgrounds across Canada and found they are
severely contaminated with arsenic leaching from play equipment made from
treated wood. More than half of 60 playgrounds in 7 major Canadian cities
had arsenic concentrations exceeding federal guidelines, some by huge
amounts. There is a general hue and cry by parents, and many
municipalities replace old wooden playground equipment with plastic or
metal. Remediation also involves replacing contaminated sand or soil under
equipment.
In June the PMRA releases a new fact sheet on CCA wood. Target date for
completion of reevaluation: late 2003. The fact sheet announces the
voluntary withdrawal of CCA wood for residential applications by the end of
2003. It is still available for industrial use. There is a list of
alternative products still registered, which don't sound much better. The
amount and rate of leaching from CCA wood depends on the wood species,
amount of rain, pH of rain, soil type, age of structure. The reevaluation
includes an assessment of the risks to children. The PMRA says you don't
need to remove CCA wood but you may want to coat it with a penetrating
stain, which slows down the leaching. You shouldn't use deck wash or
bleach on CCA wood because it speeds up the leaching.
2004: Received a PMRA update yesterday (Mar.17/04) stating EPA has
released preliminary occupational and environmental risk assessments for
CCA , directing people to US website
http://cascade.epa.gov/RightSite/dk_public_home.htm. It took me a couple
of tries to make that work, and I have not yet waded through all the
documents there. There is a 60 day comment period, at least in
Canada. The update also says a preliminary risk assessment on children's
exposure was released in November 2003 and is in the process of being
finalized.
If you've stayed with me this far, here's my understanding of the practical
advice on CCA wood:
It's water soluble, and it leaches. It should never be used in a marine
environment (they're evaluating the hazards to freshwater and marine
ecosystems, too). It should never be used in contact with human or animal
food (don't put food on that pressure-treat picnic table). Don't build
raised beds for edible plants out of it. Don't plant crops next to your
pressure-treat fence. Arsenic supposedly does not travel far in the soil,
but I haven't found a definition of "far" in this context, and it obviously
varies with site conditions. I remember seeing something years ago that
said the toxins accumulated mostly in root crops, including carrots, less
so in leaves, less in fruit.
There are a lot of concerns regarding children, because their bodies are
smaller, immune systems less developed, and they put their hands in their
mouths. The green coating can rub off the wood.
The worst thing you can do is to burn pressure-treated wood, because the
smoke and the ash are highly toxic, and can travel. If you must handle CCA
wood, you must wear goggles, gloves, and a dust mask. Don't inhale the
sawdust. Wash your hands before you eat, smoke or drink. Wash your
clothes before you wear them again, and wash them separately from other
clothes. Clean up all the sawdust. As far as I know, municipal dumps are
still accepting old pressure treated wood, although I was taught in my
landscape construction classes years ago that it is toxic waste and should
be disposed of separately. It shouldn't need saying, but don't compost
sawdust or wood scraps.
That's my summary of where it stands now. Hope this helps. I have put my
new kitchen garden in the middle of my backyard to keep it away from my
neighbours' pressure treat structures. The existing deck in our yard is
painted with penetrating stain, and will eventually be removed. (I'm
planning to do it soon, while I can still get rid of the thing.) All of
you that built your garden structures from cedar can rest easy.
Oh, one more thing: creosote and pentachlorophenol are also being reevaluated.
Carol Hughes 

_______________________________________________
gardenwriters mailing list
gardenwriters@lists.ibiblio.org
http://lists.ibiblio.org/mailman/listinfo/gardenwriters
GWL has searchable archives at:
http://www.hort.net/lists/gardenwriters
Send photos for GWL to gwlphotos@hort.net to be posted
at: http://www.hort.net/lists/gwlphotos
Post gardening questions/threads to
"Organic-Gardening" <organic-gardening@lists.ibiblio.org>
For GWL website and Wiki, go to
http://www.ibiblio.org/gardenwriters