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E-M:/ New Information on Wood Preservatives Containing Arsenic and/orChromium

Enviro-Mich message from Lowell Prag <lprag@mail.msen.com>


Below is a recent post to the U.S Composting Council newsgroup which
should be of general interest. For those wanting more technicial info
on this and other matters relating to both small scale and large scale
composting as a solution to many of our problems, I urge you to subcribe
to the newsgroup: http://mailman.cloudnet.com/mailman/listinfo/compost

Lowell Prag

---------- Forwarded message ----------
Date: Fri, 19 Mar 2004 10:32:17 -0500
From: Rufus Chaney <chaneyr@ba.ars.usda.gov>
Reply-To: compost@compostingcouncil.org
To: compost@compostingcouncil.org
Subject: [USCC] New Information on Wood Preservatives Containing Arsenic
    and/orChromium (CCA, etc.)

Dear Composters:

I got this message from an EPA colleague. I suspect the issues about CCA contaminated wood will continue to grow in public concern, and complexity. There will be law suits about play structures, raised bed garden containers, composting boxes, and anything else made from CCA to which the public has contact. And even accidental mixing of shredded CCA wood products being admixed with other compostables will be problems across the US rather than mostly in Florida. Composters in FL have had trouble for several years because some FL officials have set unrealistically low As limits for compost products, at or below soil background for FL sandy soils. But no matter how extreme  the standard being enforced in FL, it has stopped marketing of composted woody wastes. I am simply commenting that people in the business of composting organic debris and marketing compost products or chipped woody materials, should be paying more attention to the details of regulatory attention and research about CCA treated wood.

1.  The Federal Register Notice published March 17, 2004, and this notice opened the 60-day public comment period, which will close May 17, 2004. The Federal Register Notice for this risk assessment can be found at  http://www.epa.gov/fedrgstr/EPA-PEST/2004/March/Day-17/p6007.htm.

      EPA is releasing for public comment its preliminary risk assessment that evaluates potential exposure and risk to workers from exposure to wood preservatives containing arsenic and/or chromium and its assessment of ecological effects.  This preliminary risk assessment was developed as part of EPA's six-phase Public Participation Reregistration Process for wood preservatives containing arsenic and/or chromium,  and includes Chromium Copper Arsenate (CCA), Ammoniacal Copper Zinc Arsenate (ACZA), and Ammoniacal Copper Arsenate (ACA).  Acid Copper Chromate (ACC) is also a wood preservative containing arsenic and/or chromium; however, it is subject to a voluntary cancellation action and is not part of this risk assessment.

     These preservatives are used for specialized applications or in cases where wood penetration by CCA chemicals cannot be achieved (e.g., ACC used for cooling tower applications, ACA and ACZA used on large dimension wood products made from hard-to-treat wood species such as Douglas Fir).   The occupational exposure chapter addresses potential exposures and risks of chromium (Cr) and arsenic (As) to humans who may be exposed to CCA and related arsenicals and chromated wood preservatives in "occupational settings" including:  (1) handlers (mixers, loaders, applicators) of CCA and related pesticide products; and (2) individuals who are exposed to CCA and related pesticides through postapplication or reentry activities. The full preliminary risk assessment is available in the EPA docket, OPP-2003-0250.  Later today, questions are answers will be posted on OPP's web site at www.epa.gov/pesticides, under wood preservatives.

EPA Contact
Susan Laing, Ph.D., Division Communications Officer
Antimicrobials Division, Office of Pesticide Programs (7510C)
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
phone: 703 308 0152
fax: 703 308 6467


2.  A new paper on migration of CCA components into soil within raised planting beds was recently published in Journal of Environmental Quality. Besides sampling, they did a test of Cr, Cu and Arsenic uptake by 4 vegetable crops from the "near wood" soil and found enough uptake to cause concern compared to previous publications on uptake of CCA wood treatment residues leached from products in use. That Citation and Abstract are:

Rahman, F.A., D.L. Allan, C.J. Rosen and M.J. Sadowsky. 2004. Arsenic availability from chromated copper arsenate (CCA)-treated wood. J. Environ. Qual. 33:173-180.
	"Lumber used to construct raised garden beds is often treated with chromated copper arsenate (CCA). This project aimed to determine (i) how far As, Cu, and Cr had diffused away from CCA-treated wood surfaces in raised garden beds under realistic conditions, (ii) the uptake of these elements by crops, and (iii) the effect of CCA solution on soil bacteria. This study showed that As, Cu, and Cr diffuse into soil from CCA-treated wood used to construct raised garden beds. To determine crop uptake of these elements, contaminated soil 0 to 2 cm from the treated wood was obtained from two different beds (40–50 mg kg-1 As); control soil was collected 1.5 m away from the treated wood (<3–10 mg kg-1 As). Four replicates of carrot (Daucus carota var. sativus Hoffm. cv. Thumbelina), spinach (Spinacia oleracea L. cv. Indian Summer), bush bean (Phaseolus vulgaris L. cv. Provider), and buckwheat (Fagopyrum esculentum Moench cv. Common) were grown in pots containing these soils in a greenhouse. After harvest, plant materials were dried, ground, digested, and analyzed for As by inductively coupled plasma–hydride generation (ICP–HG). Concentrations of As in all crops grown in contaminated soils were higher than those from control soils. The levels of As in the crops remained well below the recommended limit for As set by the United States Public Health Service (2.6 mg kg-1 fresh wt.). To determine if bacteria in soils 0 to 2 cm from the treated wood had higher resistance to Type C chromated copper arsenate (CCA-C) solution than those from reference soils, dilution plates were set up using quarter-strength tryptic soy agar (TSA) media and 0 to 22.94 g L-1 (0–1.25% v/v) CCA-C working solution. The microorganisms from soils adjacent to treated wood had greater growth on the CCA-amended media than those from reference soils outside the bed."


Rufus Chaney
Beltsville, MD
Compost maillist  -  Compost@compostingcouncil.org

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