The Lumber Industry has many different ways of treating wood so that the wood
will not rot / be eaten by insects / fall apart. Some of the different ways
that wood is treated are:
1) Creosote
2) CCA (Chromated copper arsenate)
3) ACZA (Ammoniacal copper zinc arsenate)
4) Borate Preservatives
5) Copper naphthenate
6) ACQ (Ammoniacal Copper Quat)
7) CC (Ammoniacal copper citrate)
8) CDDC (Copper dimethyldithiocarbamate)
9) CBA (Copper Boron Azole)
See
http://www.fpl.fs.fed.us/documnts/techline/III-1.pdf for a full description.
There are some fact
sheets about CCA on the Internet but you have to critically read each to make sure
that the authors perspective (or monetary interests) doesn't taint the article.
While some of these treatments of wood were thought to be safe in the past for use
in residential areas and playgrounds, it has recently been found that some of the
chemicals leach out of the wood and may pose a hazard to humans. Children are
especially susceptible because of their size.
While CCA is
being phased out, it is still in many residential structures. When working with
this wood, BE SURE to follow standard safety precautions as described in the web site
http://www.preservedwood.com/ and
specifically in the FAQ:
Q. What additional safety equipment do I need while working with CCA-treated wood?
A. Use standard safety equipment and common sense when working with all types of
building materials. Eye protection and dust masks should be used when sawing or machining
any wood product, treated or untreated. Inhalation of sawdust can cause nose and throat
irritation. Protecting your eyes from any foreign matter while sawing or machining is good
safety practice. Wearing gloves provides extra protection against splinters. Practicing
good housekeeping hygiene at the completion of any construction project is always advisable.
This includes washing hands and cleaning up sawdust in the work area. Any other
recommendations by the EPA are based on OSHA requirements for all wood products.
Here is some additional information that I found while looking around the Internet for
more information on this kind of wood. Please read the material on this page with a
skeptical eye as some of the sites have their own bias.
Search for leaching of CCA and Creosote:
http://www.google.com/search?q=Creosote+treated+wood+leach+rate
http://www.google.com/search?q=Arsenic+treated+wood+leech+rate
Leach rate of CCA:
http://www.fpl.fs.fed.us/documnts/pdf2002/lebow02a.pdf
http://www.dph.state.ct.us/Publications/ BCH/EEOH/pressurtr.pdf
Can Garden Plants Take Up Enough Arsenic to be a Concern?
There is very little need to test soils for leached arsenic. Rather, the key precaution is
that soils beneath and directly adjacent to CCA-treated wood structures not be used for play
or gardening activities.
Should Soils be Tested for Arsenic Contamination?
http://ipcm.wisc.edu/wcm/pdfs/1999/99-5soils1.html
Is Treated Lumber a Risk in the Home Garden?
http://environment.alachua-county.org/Pollution_Prevention/ hazmat/CCA%20REPORT.PDF
Safety working with CCA wood:
However, according to news reports, essentially all documented human health impacts have
been to individuals who have been working with CCA wood; primarily sawing and sanding. These
activities resulted in exposure to CCA wood dust with subsequently identified health effects.
Unlike children on playgrounds, workers can adequately protect themselves from these impacts
through being informed about the potential hazards (material safety data sheets and similar
information sources), the proper use of personal protective equipment (dust masks, gloves, etc.),
and sensible work practices (ventilation, washing hands and clothing after work, and not eating
or drinking in the work area). The key issue that has been lacking for workers (including
do-it-yourselfers) on a nation-wide basis is the lack of available information about the health
hazards of CCA wood.
Does Pressure-Treated Wood Belong in Your Garden?
http://www.taunton.com/finegardening/pages/g00028.asp
Intensive Vegetable Gardening:
http://www.ces.ncsu.edu/depts/hort/consumer/quickref/vegetable/intensive_veg_gardening.html
Remove arsenic from your soil:
http://www.checnet.org/healthehouse/EDUCATION/ARTICLES-DETAIL.ASP?MAIN_ID=593
Web site: http://www.altpest.org
Page on the history:
http://www.sptimes.com/News/070201/State/Treated_wood_industry.shtml
http://www.environmentalhealth.ca/w99wood.html
Copper, chromium and arsenic leaching from new and weathered wood were found at all pH levels,
with higher metal concentrations in acidic conditions. At pH 5.5, for instance, 92% of the
copper, 12% of the chromium and 32% of the arsenic leached out. This raises concern for the
amount of leaching caused by acid rainfall along eastern areas of Canada and the U.S. It also
means that the rate of leaching is accelerated in acid environments such as bogs, silage and compost.
http://www.neia.org/policies/wat9301.htm
Leaching of Chromated copper arsenate (CCA):
http://clir.buffalo.edu/nycap/htm/pdf/Arsenic_WNY.pdf
Additional Resources:
http://www.cpsc.gov/phth/cca.html
http://www.epa.gov/pesticides/factsheets/chemicals/cca_qa.htm
http://www.atsdr.cdc.gov/toxprofiles/tp2.html
http://www.beyondpesticide.org
http://www.ewg.org/issues/home.php?i=7
http://assembly.state.ny.us/leg/?cl=37&a=153
http://www.dec.state.ny.us/website/dshm/sldwaste/cca.htm
http://www.cleanwateraction.org/pdf/fact_cca.pdf
Creosote is a distillate of coal tar produced by high temperature carbonization of bituminous coal.
Creosote Leaching:
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn286.pdf
http://www.metrokc.gov/health/hazard/treatedwood.htm
And why Creosote doesn't get into plants (
but is carcinogenic), however
it does retard the plant growth:
Creosote can volatilize into the air, especially during hot weather, and plant foliage in the
vicinity of the ties may be damage by the vapors. It can also leach into the soil near the ties,
but it will not be absorbed by the roots and will therefore not get into the plants' tissues.
http://www.dti.gov.uk/ccp/topics1/facts/creosote.htm
My raised garden bed consists of creosote-treated railway sleepers. Should I be digging these up?
No. Wood treated with creosote prior to the coming into force date of the Creosote Directive, may be
used in gardens, providing there is no risk of frequent skin contact. Furthermore, the prohibition
on the use of treated wood does not apply where the treated wood was in such use before 30 June 2003,
the date these Regulations came into force.