Health concerns of pressure-treated deck
Q: Myhusband and I installed a pressure-treated deck about 15 years ago. We did notknow then what we know now about the chemicals and carcinogens that were usedin the manufacturing process. We installed a second redwood deck on a backportion of the house about eight years ago. We’re now interested in tearing outthe pressure-treated deck and replacing it with redwood for one consistent lookand maintenance plan. Our questions are:
1. Isthere any risk involved to people removing a pressure-treated deck? Shouldworkers wear protective gloves or masks?
2. Becausepressure-treated lumber is toxic and non-biodegradable, where is an appropriateplace to dump the deck pieces once they are removed?
3. Haveyou heard any studies or read any anecdotes about anyone (pets included)getting sick from living with a pressure-treated deck? I ask because our dogsoften chew and lick toys and bones on that deck.
A: Morethan 70 years ago, Karl Wolman invented a system to infuse wood withpreservatives. Wood is placed in a large cylindrical tank, and the tank isdepressurized to remove the air. Then chemical preservatives are pumped intothe tank under high pressure, forcing the liquid preservative deep into thewood. Incisions are often cut in the wood to allow the preservative topenetrate deeper.
The resultis a wood product that will not rot or decay for more than 20 years, even underthe most extreme conditions.
The mostcommon preservative used to treat wood was chromated copper arsenate, or CCA.The arsenate part of the formula refers to arsenic, an extremely toxicchemical. Concerns over safety have led to the voluntary discontinuation of themanufacture of CCA-treated wood for residential use by the industry, althoughCCA will continue to be used in some industrial applications.
In 2004the use of CCA for residential use began to be stopped. Two alternativepreservatives will take the place of CCA over the next several years. They areamine copper quat (ACQ) and copper azole (CA).
As withCCA, copper is the dominant ingredient in these preservatives. According to theForest Products Laboratory of the Department of Agriculture, there is littlepractical difference between CCA and these alternatives.
However,ACQ and CA are more expensive, so the amount of preservative infused into woodwill differ between “in-ground” and “above-ground”applications. Lumber will be marked for each application. Use it according tothese guidelines.
Foradditional information visit the Forest Service’s Forest Products Web site, www.fpl.fs.fed.us.
Here areour answers to your questions, but before we begin, let us calm what might be aconcern. Existing decks made of pressure-treated lumber pose no danger. Likeasbestos, if you leave them alone, no problem.
To bedoubly safe, though, be advised that CCA contained in the surface residue oftreated boards is water soluble. Some of thepreservative can leach from the wood when it gets wet. Application of apenetrating oil stain or sealer can encapsulate the residue and alleviate thisproblem.
Now toyour questions. Workers who remove your deck should wear gloves, long-sleevedshirts and long pants. Wear a dust mask to avoid inhalation of any of thepreservative-laden particulates. Wear safety glasses or goggles. Finally, washwork clothes separately from other laundry to avoid cross contamination.
As todisposal, do not burn the wood or mulch it. Also, try to capture any sawdustand debris resulting from the demolition and dispose of that also.
In 2004the California Legislature passed Assembly Bill 1343 governing disposal oftreated wood waste. Under this law, pressure-treated lumber may be disposed ofin a hazardous-material landfill or in a composite-lined portion of a municipallandfill that meets specific requirements. Contact your local landfill todetermine whether there are any restrictions to dumping your deck there.
Finally,we haven’t heard of any toxic effects on pets from playing on pressure-treateddecks. However, CCA residue on the surface of treated boards is water soluble,so excessive licking of the wood itself could transfer the toxins to your pet.
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Copyright 2007 Bill and Kevin Burnett
