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Outdoor wood, used widely in home landscape projects, is protected from moisture, rot and insect damage with chemical preservatives (pesticides) to inhibit fungal decay and extend the life of the wood. The wood treating industry estimates that treated wood will last 20 to 30 times longer than untreated wood in challenging outdoor environments. The benefits of treated wood include longer useful life and conservation of trees. However, the chemicals used to preserve it are toxic which present environmental problems especially when the wood is taken out of service requiring disposal. To prevent treated wood from causing adverse health and environmental impacts, it makes good sense to select, use and dispose of treated wood products appropriately. There are three broad categories of preservative treatments for wood currently in use:
Creosote is a highly complex mixture of chemicals distilled from coal tar, which is a by-product of producing coke from bituminnous coal in coking ovens. Creosote is essentially an oil-based compound. The most common oilborne preservative is pentachlorophenol, generally known as penta. Penta has been shown to cause birth defects and fetal damage, among other health problems. Both creosote and penta have been a restricted-use pesticide since 1986. Copper naphthenate is the other fairly common oilborne preservative. Today, waterborne preservatives are widely used in building applications. These waterborne chemicals are used in pressure-treating only and include chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA), ammoniacal copper quaternary compound (ACQ), and several others. CCA accounted for 94% of the waterborne chemicals used in 1995. By themselves, the primary CCA chemicals are highly toxic and are regulated as pesticides by the EPA. However, in treated wood, they become tightly bonded to the wood during fixing, so leaching from the wood is minimal under normal usage conditions. ACQ is the most popular copper based alternative to CCA. This alternative eliminates the toxic components of arsenic and chromium. Using Treated Lumber. A number of factors should be considered before using treated lumber. For instance, where will it be used; indoors or outdoors? Will people or animals come into direct contact with the wood? Will the wood come into contact with any drinking water source, any water body (such as a lake or stream), or with ground water? Is there a less toxic or nontoxic option to using treated lumber? Never inhale the sawdust when cutting treated wood. Always wear a dusk mask. Consumer Information Sheets are published as federal guidelines by the U.S. Environmental Protection Agency and the wood-treating industry. Sellers of treated lumber will have these sheets available to the consumer. Some of the important federal guidelines for using treated lumber include:
Follow these additional precautions:
Disposal Options for Treated Lumber The first priority in keeping treated wood out of the waste stream should be salvage and reuse. If such wood does not enter the waste stream, it will not be considered waste. Therefore, whenever possible, try to reuse treated wood that has been taken out of service, as long as it still meets the design requirements. If you must dispose treated wood, follow these recommendations:
As much as possible, avoid specifying or using CCA-treated wood. Use construction details that minimize use of wood in locations where rot or insect infestation is likely. If wood must be used, go with one of the newer, copper-based products, such as ACQ Preserve. Naturally rot-resistant species such as cedar are an option, especially if available from certified, well-managed forests. Avoid rot-resistant species from domestic old-growth or tropical rain forests. Additional Information
This information is provided as a service to those professionals in the construction industry. This information does not include all available references and does not constitute an endorsement by DEEP. Use of this information does not in any way lessen your responsibilities for compliance with applicable federal, state, and local laws. For more information contact Frank Gagliardo at (860) 424-3130. Content Last Updated May 22, 2013 |
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