WASHINGTON - Under an agreement with the U.S. EPA, manufacturers of pressure-treated wood will voluntarily discontinue the use of treatment products containing arsenic by Dec. 31, 2003, the EPA announced.

The EPA said the agreement affects "virtually all residential uses of wood treated with chromated copper arsenate," or CCA, including treatment of wood used in play structures, decks, picnic tables, landscaping timbers, residential fencing, patios, and walkways.

EPA Administrator Christine Whitman said the agreement "greatly accelerates the transition to new alternatives" to CCA, and said the phaseout "will substantially reduce the time it could have taken to go through the traditional regulatory process."

Suppliers of CCA wood-treatment products quickly announced that they are marketing alternative products and expect use of those materials to expand rapidly following the EPA agreement.

The EPA said arsenic is a known human carcinogen and "any reduction in the levels of potential exposure to arsenic is desirable." But the agency said it has not concluded that CCA-treated wood poses "unreasonable risks to the public" where it currently is in use. CCA-treated wood that continues to be available for sale also is not stated to pose such risks.

The EPA recently began an evaluation of CCA-treated wood under provisions of the Federal Insecticide, Fungicide, and Rodenticide Act, which direct the agency to periodically reevaluate older pesticides to ensure that they meet current safety standards. The agency said it is continuing to proceed with a risk assessment of CCA-treated wood.

Arch Chemicals Inc.'s Arch Wood Protection Inc. subsidiary, a major supplier of CCA products for wood treatment, is marketing alternative products used on wood sold under the trade name "Wolmanized Natural Select." The company said the preservative used in the product line has been approved for use by the EPA, and is described as a copper azole that employs copper and an organic fungicide as co-biocides.

An Arch Chemicals spokesman said approximately 10 U.S. companies that pressure-treat lumber began using the preservative last year, with significantly expanded use anticipated.

Arch Wood Protection said it will continue to produce CCA for industrial end-use applications such as highway construction, utility poles and pilings. The company said it "stands by the safety of wood products treated with CCA and continues to support sound scientific research, which has consistently upheld the safety of CCA-treated wood when used as recommended."

Other major suppliers of CCA wood-treatment products, including Chemical Specialties Inc. of Charlotte, NC, and Osmose Inc., Buffalo, NY, also are offering alternative products and are participating in the EPA-announced phaseout program for CCA in residential applications. Those alternative products include co-biocide treatments incorporating copper and quaternary compounds.

New wood-preservative products based on different technologies are also appearing, such as a polyurea-based coating from Innovative Coatings Corp. that is designed to encapsulate the wood with a tough, non-toxic shield to prevent water and insect penetration.

Innovative Coatings, based in Atlanta, said the wood-preservative product also can be applied to lumber previously treated with CCA to prevent leaching of arsenic compounds - and thus protect people from coming into contact with arsenic.

Innovative Coatings is a producer of polyurea-based coatings for a variety of applications, including pipelines, rail cars, truck-bed liners, concrete protection and waterproofing, roofing, and others.