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PRI's Environmental News Magazine

ARSENIC IN WOOD

Air Date: Week of July 25, 1997

Pressure-treated wood used to make patio decks and picnic tables contains chemicals that may pose health risks. Even arsenic is sometimes used in the pressure treatment process according to Alex Wilson, editor of Environmental Building News, who spoke with Laura Knoy.

Transcript

KNOY: Summer time, for many people, is the time to get out the grill and have the neighbors over for a barbecue on that great new wooden deck you had built this spring. But before you break out the burgers, check to see what type of wood your patio's made of. A steady stream of research shows that some types of pressure-treated wood often used in outdoor settings can be dangerous to human health. Alex Wilson is editor and publisher of Environmental Building News, a newsletter on environmentally responsible design and construction. He's written about pressure- treated wood, and he joins us now. And Alex, thanks for coming in.

WILSON: Glad to be here, Laura.

KNOY: Why treat wood in the first place? What's the advantage?

WILSON: Well, there are a lot of advantages of treating wood. The preservative in wood keeps insects from damaging it, keeps bacteria from coming in, keeps mold from causing rot and degradation.

KNOY: Alex, how does somebody know if they have a deck or a patio that's made out of pressure-treated wood?

WILSON: Well, when the deck is new, it will have a greenish tint to it. Unfortunately, as it ages, and particularly with a 20-year-old deck, that wood will naturally gray and it will become difficult to determine exactly what it's made of. The rule of thumb would be to always assume that it is made of treated wood.

KNOY: What are some of the products that people would be familiar with that are made out of pressure-treated wood?

WILSON: Well, the most common would be decks. The typical back yard wooden deck is made of a treated wood called CCA, or chromated copper arsenate. Some picnic tables are made of treated wood that's used quite a bit in playground construction.

KNOY: Lots of wood is treated with what you called chromated copper arsenate or CCA, and in a recent article that you wrote in Environmental Building News you said not only is this the most common type of treated wood, it's also the one that's the biggest cause for concern.

WILSON: Some 5 billion board feet per year of wood are using this preservative treatment. And our concern is looking down the road at what is going to happen when this wood begins coming out of service. CCA-treated wood went into widespread use beginning in the early 70s. Fairly soon, very large quantities are going to begin entering our waste stream.

KNOY: If people burn it, there's a concern.

WILSON: Burning it is always a problem. Homeowners should never burn any type of pressure- treated wood or preservative-treated wood under any circumstances. The chemicals that are in the most common pressure-treated wood are heavy metals: chromium, copper, and arsenic. Those 3 chemicals may become airborne. Most of the heavy metal will end up in the ash, and in that form in the ash it is highly leachable and can easily get into groundwater and cause all kinds of environmental concerns.

KNOY: So if I've got a deck made out of CCA-treated wood and it's time for me to get rid of it, what should I do?

WILSON: The only thing that can be done with it is landfilling it. So you should check with your municipal solid waste authority and find out what happens with wood that gets sent out with the trash. If the municipal trash goes to an incinerator, my recommendation would be to talk to your solid waste agency and say look, I've got pressure-treated wood in here. From what I understand that should not be incinerated. What are the alternative disposal options?

KNOY: If the wood is still in good condition and you're using your deck or your patio or whatever, should you be concerned about people spending time on it? About your kids spending time on it?

WILSON: Well, that's a big issue of contention. Some recent studies, one in particular in Connecticut, looked at the arsenic and chromium concentrations beneath a number of decks that had been built out of pressure-treated wood, and found significantly elevated levels. I've also read some counters to that study by the American Wood Preservers Institute. But even they will admit that there will be some leaching of the chemicals from that.

KNOY: Where do you see it going? Where do you see the wood products industry going with treated wood, given the concerns that you've talked about today?

WILSON: I don't know. In our newsletter we actually took the unusual step of calling for a gradual phase-out of CCA-treated wood. We're not an advocacy-type publication, but we did feel that this was significant enough an issue that we needed to take a stand on it. I should note, however, that there are some new products coming along that are quite attractive from an environmental standpoint, and highly durable. There are 2 products on the market that are a composite of recycled polyethylene and wood fiber. One is called TREX; it used to be made by Mobil Chemical, it's been spun off as a separate company. The other product is made by AERT in Texas, and that's a quite interesting product called Choice Deck. It's distributed by Weyerhaeuser now. But it's a 50-50 mixture of recycled polyethylene and waste wood fiber that's left over after perfume manufacturing in Texas.

KNOY: So in terms of the future, it sounds like some alternatives are being developed.

WILSON: Very much so. As concerns become more publicized about CCA and particularly the long-term disposal of CCA, we will begin to see a shift toward safer products.

KNOY: Well Alex, I want to thank you very much for joining us.

WILSON: I’m glad to be here.

KNOY: Alex Wilson is editor of Environmental Building News and author of the Consumer Guide to Home Energy Savings. He lives in Brattleboro, Vermont.

 

 

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