ARSENIC WOOD: HAZARDS AND ALTERNATIVES
Where is arsenic used?
Arsenic is widely used as a preservative in pressure treated wood in the United States. Pressure treated wood is often found in:
- building foundations
- boat docks
- playground equipment
- picnic tables
- or wherever wood must be protected from decay
The most common arsenic formulation used in the United States is Chromated Copper Arsenate (CCA). CCA consists of chromium (a bactericide), copper (a fungicide) and arsenic (an insecticide) and is often sold under the trade name "Wolmanized" wood. Ammoniacal Copper Zinc Arsenate (ACZA) is a very similar arsenic formulation sold primarily on the West coast as Chemonite. ACA and ACC are two more less widely used arsenic treatments.
Why is arsenic wood a problem?
- Inorganic arsenic is a known carcinogen. Arsenic has been linked to skin, bladder, liver and lung cancers. Human and animal data suggest that inorganic arsenic is also a reproductive hazard. Released arsenic can find its way into our bodies, the food chain, and groundwater. Arsenic has been identified by the Swedish government as a "sunset" chemical - a chemical whose use should be phased-out due to extreme potential for environmental and human health damage
- Children can ingest it. Although the wood preservation industry argues that the CCA wood preservation process "fixes" the arsenic into the wood and effectively prevents significant quantities of arsenic from being released through contact or leaching into soil and water, recent evidence contradicts this claim. A number of recent studies have confirmed that high levels of arsenic can be released to children's hands by direct contact with arsenic treated wood. A University of Florida study of soil below CCA wood decks found that surface soil arsenic concentrations below the decks were elevated on average by 2000%
- It is poisoning our soil and water. Although arsenic has been virtually banned by the EPA as a pesticide, the wood treatment industry was able to gain an exemption to this rule. Currently, the industry is responsible for the import of more than 30 million pounds of pure arsenic into the U.S. each year. Ultimately, the vast majority of this will end up in local landfills where it can leach into soil and local waterways.
- Burning CCA wood creates a highly toxic ash. One tablespoon of ash from a CCA wood fire contains a lethal does of arsenic. This has serious implications for firefighters and clean-up operations.
What to do with existing wood
- Test it. If you donít know if the wood is arsenic treated you should test it. Test kits are available from the Healthy Building Network web site.
- Replace it. There are many safer alternatives available (see below)
- Seal it. If you canít replace it, thoroughly coat it at least every two years (annually or better in high traffic areas) with a waterproof sealant such as polyurethane or an oil based penetrating sealer. Do not use acid deck wash or brighteners as these are suspected to accelerate the release of arsenic from arsenic treated wood.
- Donít burn it. Never burn treated wood. Arsenic treated wood is hazardous and should be disposed of properly according to local environmental regulations
Safer alternatives for new construction
A wide range of less toxic alternatives are available on the market today. Most of them, including the two alternative pressure treatments, have proven equally effective at protecting against decay as arsenic treatments in tests by the university of Florida. Note also that ACQ and CBA are manufactured by the same companies that make the arsenic treatments.
- ACQ - Ammoniacal Copper Quaternary. An alternate wood pressure treatment widely marketed as ACQ Preserve and ACQ Preserve Plus by Chemical Specialties (distributor locator is available on their web site at www.treatedwood.com. Check off "Preserve"and "Preserve Plus" for product type to search
- CBA - Copper Boron Azole a newer alternate wood pressure treatment just becoming available in the US lumber yards. Sold as Wolmanized Natural Select by Wolman. (www.naturalselect.com)
- Boron Ė Borate based treatments can be field applied to wood. For use where wood is protected from weather and water.
- Pest resistant wood Ė Redwood and cedar are naturally pest resistant. Seek wood that has been certified as sustainably harvested by an FSC certifier, if possible. (www.certifiedwood.com) (www.forestworld.com)
- Plastic Ė A wide range of composites made from recycled polyethylene plastic and wood or other cellulose fibers are on the market.
This list is just a sample of what is available:
Educate your lumberyard
Read the labels and ask questions. Despite a voluntary EPA/manufacturers labeling agreement, pressure treated wood is often unmarked or poorly labeled in stores. If you're not sure or the label is unclear, ask if the lumber has been treated with CCA, ACZA or another arsenic compound. If the store clerks canít tell you exactly what it is, donít buy it. Share this fact sheet with them and explain to them why this is so important.
Ask for healthy alternatives If your lumberyard does not stock ACQ, CBA or another non-arsenic alternative, ask them to order it. They need to hear from you to know you care.