Less-Toxic Alternative to CCA Treated Wood

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Summary

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Although the Environmental Protection Agency (EPA) has concluded that Chromated Copper Arsenate (CCA), the chemical most commonly used to preservative wood, does not pose a significant health risk when used properly; there is a potentially less-toxic alternative available for softwoods. This alternative provides similar resistance to decay as traditional pressure-treated wood without any risk of exposure to chromium or arsenic.

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Details

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A less-toxic preservative chemical, Ammoniacal Copper Quat (ACQ) combines the effectiveness of copper with a low-toxicity co-biocide to achieve a high degree of preservation and durability in various softwoods. Tests of ACQ-treated wood have shown retention levels equivalent to traditional copper-based preservatives. Similar to traditional pressure-treated woods, ACQ-treated wood has a predicted service life of 30 to 40 years or more. Its color can vary from light tan to a deep olive and it weathers to a brown rather than gray. The non-toxic compound does not have any impact on the mechanical properties of wood.

ACQ-treated wood is as easy to work with as untreated wood of the same species, but when sawing and machining, eye protection and a dust mask is advised to protect against flying particles. Because ACQ-treated wood will probably be used in environments where corrosion is likely to occur, corrosion-resistant, hot-dipped, galvanized and stainless steel fasteners are recommended. When finishing, wood should be dry, oil-based semi-transparent stains should be used, and low-quality latex products should be avoided. Different retention rates of ACQ-treated wood are specified for applications above ground and with ground contact, as well as for permanent wood foundations, poles, and pilings.

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Installation

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n/a

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Benefits/Costs

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ACQ-treated wood has the same preservative benefits as conventional preservative-treated wood, and has low leaching and depletion rates that compare favorably with other copper-based preservatives. The ACQ biodegradable co-biocide may be easier to dispose than the potentially hazardous arsenic and chromium metals in conventional pressure-treated woods. ACQ-treated wood is available in a variety of wood species.

The cost of ACQ-treated lumber is typically about 10 percent higher than conventional CCA-treated lumber.

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Limitations

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ACQ-treated lumber is more expensive than conventional CCA-treated lumber.

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Code/Regulatory

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ACQ-treated wood contains no chemicals that fall under regulation of the Superfund Amendments and Reauthorization Act (SARA), the Toxic Substances Control Act (TSCA), and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Dust from any wood source, treated and untreated, is considered a carcinogen by the International Agency for Research on Cancer. Therefore, carcinogenicity warnings are required on treated wood products shipped into California, including ACQ-treated wood. When cutting or sawing wood, it is recommended that a mask and goggles are worn for personal protection. This practice is also recommended for ACQ-treated wood, The EPA also recommends cutting outdoors, washing hands, and laundering clothes separately after use. ACQ-treated wood can be disposed of in the normal waste stream or as advised by your local waste regulatory authority.

The chemical components of ACQ are EPA-registered, general-use pesticides that are less toxic than chemicals in conventional wood preservative systems. Unlike traditional preservative systems, none of its components are listed under toxicity characteristics of rule 40 C.F.R. 261.24 (55 Federal register 11862). ACQ is accepted by the American Wood Preserver's Association (AWPA) and the International Conference of Building Officials (ICBO).

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Availability

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The preservative compound is sold by one manufacturer under the trade name "ACQ Preserve." Wood treated with ACQ is not available in all states.

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Contact(s)

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Do you have a specific question about this technology and/or its 'real life' applications? Try the contacts listed below:

American Wood-Preservers Association
3426 Fall Creek Highway, Suite 190
Granbury TX 76049-7979
Phone: 817-326-6300.

B. B. & S. of New England
PO Box 982
Davisville, RI 02854
401/295-3200

Chemical Specialties, Inc.
One Woodlawn Green, Suite 250
Charlotte, NC 28217
800/421-8661

Chicago Flameproof
PO Box 318
Montgomery, IL 60538
630/859-0009

Conrad Wood Preserving
3998 Wildwood Drive
North Bend, OR 97459
541/756-2595

J. H. Baxter & Co.
P. O. Box 5902
San Mateo, CA 94402
650/349-0201

McArthur Lumber and Post
313140 State Route 93
McArthur, OH 45651
740/596-2551

National Pesticide Telecommunications Network
Agricultural Chemistry Extension
Oregon State University
333 Weneger Hall
Corvallis, OR 97331-6502
800/858-7378

Northern Crossarm Co., Inc
PO Box 34
Chippewa Falls, WI 54729
715/723-0861

Quality Forest Products
Route 1 Box 406 QF
Enfield, NC 27823
252/445-2113

Superior Wood Treating
13702 8th Street East
Sumner, WA 98390
253/863-4495

NeemGreen, Inc.
P.O. Box 1966
Melrose, FL 32666
352-475-5245