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Pressure-Treated Lumber - Should You Be Concerned?

Blood poisoning. Cancer. Infection.

These have all been linked to pressure-treated (P/T) lumber in recent years. How real are these risks, and what, if anything, should you do about them?

P/T lumber has been used for many years to resist rot, decay and insect infestation. It has become common in the construction of porches, decks and areas where wood is likely to come in contact with moisture or earth, such as sill plates on foundations. P/T lumber typically has a greenish tint. In addition, you should be able to find a stamp on the material that identifies it as pressure-treated and/or rot- and insect-resistant. P/T lumber is sold under many different brand names.

Although P/T lumber does its job well, in recent years it has come under increasing attack by environmental and safety-conscious consumer groups for its alleged risks. How significant this is for you, as a homeowner, is still unclear. So far, no one has been willing to say just how much of a risk P/T lumber represents. However, apparently it is enough to cause a major change in the industry.

More specifically, the wood preservative industry has entered into a voluntary agreement with the EPA to stop producing pressure-treated wood products treated with CCA (chromated copper arsenate) for the residential building market and consumer-related products by December 2003. This is not expected to affect industrial and commercial products or those used in saltwater marine applications.

What is CCA? CCA is a chemical compound that works to preserve wood. It is made up of copper, chromium and arsenic. The copper is the major preservative, protecting against fungi and insects. The arsenic is a second line of defense, and the chromium acts to fix the treatment, so it doesn’t easily leach out of the wood. CCA is controversial. Arsenic, however, is a known carcinogen. Many believe that it is a health threat for those who touch it. However, in negotiating with the timber industry, the Environmental Protection Agency (EPA) stopped short of calling it dangerous. Instead, they said that any reduction in the amount of arsenic in the environment is desirable. We are not aware of any credible studies that quantify the actual safety risk.

EPA has also said, in a somewhat contradictory statement, that there is no reason to remove or replace CCA-treated structures. On the one hand, CCA-treated lumber is dangerous enough to be phased out of use, while on the other hand, there is no need to remove or replace existing structures!?!

Instead of recommending removal, EPA says that applying an oil-based, semitransparent stain once a year may reduce the levels of arsenic on the surface and, thus, reduce the risk. In addition, children playing on CCA-treated wood should wash their hands before eating and never place food directly on the wood. Children should also avoid getting splinters from the wood. Ever try telling your child not to get a splinter?! If you remove CCA-treated wood, use gloves and handle it as construction debris. Do not burn it.

So what should you do? The older the structure and the more it has been exposed to weather, the less likely it is a significant hazard. How it is used (i.e. frequent and/or prolonged contact with bare skin) will help determine the degree of risk.

It is for you to judge, ultimately. In most cases, however, the risk seems manageable, and the guidelines noted above are adequate for most situations. In high traffic areas, especially where children are present, replacement or, at a minimum, regular treatment with a sealant or stain is recommended.

What will we do in the future? Rot and insect resistance will continue to be an important quality for some of our building materials. Replacements are available, but generally more expensive. They include alkaline copper quaternary (ACQ), sold under the trade name Preserve, copper boron azole (CBA) and Tanalith E, another copper-based product with an organic fungicide. Composite or vinyl building components may also see more use. Cedar and redwood are alternatives with natural rot/insect-resistant characteristics. These woods are, however, more expensive.

For more information about CCA-treated wood, go to and do a search (top right of first screen) using CCA as a search criterion. You will find several documents about current standards and commonly asked questions.

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