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Re(2): creosote
austin@mail.biddeford.com wrote:
>The following is from THE UNDERGROUND HOUSE BOOK, by Stu Campbell,
>copyright 1980 by Garden Way, Inc.:
>>"Traditional wood preservatives such as creosote and pentachlorophenol ARE
>toxic and may not be used legally in underground walls that inclose living
>space. But newer chromated copper arsenate salt preservatives are
>non-toxic, odor free, virtually unleachable and permanent. In other words,
>they're sound and safe."
Yeah, right. Please note that this was written in 1980.
There have been a number of findings since then that they do indeed leach.
One that I read about last summer in a New Jersey newspaper was a study of the
soil around 10-15 year old bulkheads in some affluent communities on the
Jersey shore. Levels of arsenic were quite elevated. I can't remember the
exact figures, but I know it worried me enough that I have completely stopped
using it since then.
I haven't put this on the web site yet, but this is an excerpt from the Wood
Treatment section of the Sustainable Building Sourcebook:
CONSIDERATIONS:
Three primary methods of wood treatment currently prevail: creosote
pressure-treated wood, pentachlorophenol pressure-treated wood, and inorganic
arsenical pressure-treated wood. The pressure-treating process is done by
commercial facilities and made available to users in the final wood product.
Copper napthenate, zinc napthenate, and tributyltin oxide are other wood
treatment options that can be site applied. All of these treatment processes
involve dangerous chemicals .
Chromated copper arsenate (CCA) is the most popular wood treatment product
available today. The chemicals are inert within the material and offer
protection from moisture and decay fungi. The chemicals do not penetrate into
the heartwood effectively so a sealer is advisable on cut ends of CCA treated
wood. Although CCA treated wood is sawn on jobsites, hardly anyone seals the
cuts. All pressure treated products require adherence to safety precautions
approved by the EPA. The safety precautions are listed in the Guidelines
section.
EPA regulations govern the manufacture of pressure-treated materials and
require extensive environmental safety precautions. Wood treatment does offer
a method to extend the usable life of our wood resources.
The toxicity of the chemicals used in wood treatment has led to research into
less toxic methods such as the use of borates derived from the natural element
boron (borax). Borates (from boron) are used in wood in New Zealand and
Australia and offer insect protection and fire retarding benefits to wood.
Full-scale commercial introduction of borates in the U.S. awaits resolution of
the leaching problem of borates. Since borates are water soluble, water
dilutes them and leaves the wood unprotected from decay after a period of
time. In a location unexposed to water, they are effective in preserving
wood; site applied borate products are available.
Borate pressure-treated wood is being offered by one company in the U.S.
(primarily for the Caribbean market). They are promoting the concept of using
borates for all the wood in a house. This eliminates the need for termite
protection by any other means and prevents decay fungi.
Ammoniacal copper quatenary (ACQ) is a new wood preservative currently being
introduced. This material employs preservative components that are listed in
EPA's
classification as "General Use" pesticides. This is a less toxic material
than CCA and it performs similarly.
**************
Please note that this section has not been revised in several years, and new
information may have come to light since it was written. The City of Austin's
Green Builder Program, which put together the Sourcebook, is currently
revising many sections of it. Paper versions are available for about $25 from
the City of Austin. Call 512-499-3500. The Web version is available at
http://www.greenbuilder.com/
--
Bill Christensen
billc@versa.com
Sustainable Building Sourcebook at http://www.greenbuider.com/sourcebook/
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