permaculture

[gardenbetty@earthlink.net]

>From Organic Gardening magazine, who is fighting EPA on their safety 
>standards
re: CCA wood:

Tests performed in 1997 by chemists at the Connecticut Ag Experiment Station
found confirmed early studies that showed that samples taken from beneath CCA
wood decks contained up to 80 times more arsenic than the surrounding soil and
as much as 35 times the legal limit for arsenic in soil.  The chemists took 85
soil samples from beneath seven different decks and found that srsenic leaches
quickly from treated wood; soil samples beneath a 4-month old deck already
contained an average of 4 times more arsenic than ordinary soil. They also
found that leaching continues as a deck ages-- soil samples beneath an 8 year
old deck average 138 ppm and one sample contained 350 ppm--35 times the 10ppm
legal limit for arsenic in residential soils. 

The manufacturers of pressure treated wood have been ignoring scientific
findings like these for decades. (Although one company spokesperson admitted
off the record to Organic Gardening that he expected CCA wood would eventually
be banned)

Furthermore, there is mounting evidence that consuming even very small amounts
of arsenic is harmful to our health.  The US Toxicological Profile revelas
that the minimal risk level for arsenic is 18 micrograms per day, and that the
average American adult already currently consumes three times that much in our
food and water.

A 1990 US Consumer Product Safety Commission study of CCA wood playground
equipment revealed that simply touching CCA wood can easily get arsenic onto
your skin. The Commission study estimated that 2 year old children can ingest
as much as 2,016 micrograms of arsenic per day by playing on CCA treated wood
and then putting their hands in their mouths. The maximum safe limit for a 25
pound toddler is 3.4 micrograms a day.

Every state is somewhat different in what they consider acceptable for organic
certification. Check with Maryland extension to get their list of prohibited
materials. I doubt CCA wood is permitted to be used around food crops.

"Contamination of Soil with Copper, Chromium and Arsenic Under Decks Built
from Pressure Treated Wood" Bulletin of Environmental Contamination and
Toxicology, volume 58, pps 22-28, 1997.

For further studies, contact Organic Gardening magazine, Treated Wood Woes c/o
Cheryl Long, 33 E Minor St., Emmaus, PA 18098.

Alternatives: black locust (fast-growing, naturally rot resistant (80 yrs or
longer), nitrogen fixing tree), cedar, cypress, redwood, post trees as
previously mentioned, living fences or hedgerows, recycled plastic lumber.

hope this helps

dawn

Charland, Stacy (NIGMS) wrote:
> 
> Hi folks;
> 
> We are currently purchasing some land, and we will need to install some 
> fencing.
> I have been looking for non-pressure treated fence posts, but most folks 
> selling
> fence posts seem to think I am crazy for wanting them, and don't carry them
> (black locust, cedar, osage orange).  I thought that you couldn't use 
> treated
> posts if you plan to be certified organic, but a number of folks on another 
> list
> (grazing list) seem to think treated fence posts are not a problem for 
> organic
> certification.
> 
> Anybody on this list know the story?  Any assistance is appreciated!
> 
> Stacy Charland
> Stacy_Charland@nih.gov
> Bethesda, Maryland  USA