Pressure Treated Wood & Vegetables

Anne Jaeger
“Wood not eat that if I were you.”
I’ve got something important I want to talk to you about. Do you have
raised garden beds for your vegetables? What kind of wood are
they made of? Don’t know? Let me help you figure it out, because you’re
gonna wanna know. Your health may depend on it, someday. If the wood is
marked with little divets in a measured pattern all along the surface
you’ve got pressure-treated wood–once the gold standard for wood used in
contact with soil. Not so, anymore.
Michael Heumann, epidemiologist with the Oregon Department of Human Services, sends out this warning; “Our advice is: get rid of it, TODAY. The problem with treated wood is that it contains arsenic and arsenic is known to cause cancer.” Ninety percent of the arsenic used in this country produces pressure-treated or CCA (Chromated Copper Arsenate) wood. No surprise there. That’s why we bought it; the chemical stops termites and prevents rot. Health experts now believe we’re eating the chemicals. Heumann also recommends you take out “the contaminated soil that’s right in contact with the wood, and replace it with clean soil and safe wood.”  He cites a university study done by the Department of Analytical Chemistry in New Haven, Connecticut which found that lettuce and tomato roots grown in raised beds built with CCA wood contains ten times more arsenic than the same vegetables grown near untreated wood.
The Environmental Protection Agency agrees that scientific studies
suggest that “arsenic, over time, slowly leaches from the CCA-treated wood
products” and will ban its use by 2004. It is still for sale–you can find
red warning labels on the ends of CCA lumber at most of the big box stores
today.  The wood products industry still stands behind CCA’s safety but voluntarily agreed to phase it out of production now. “You’ve got a product that’s been in service for over 80 years that really has a very good track record. Scientifically there’s really no data to back up any dangers. It’s mostly emotionally based” according to Dennis McWhirter of Exterior Wood Inc. of Washougal, Washington.  As a back-up, the industry is making some great alternatives. McWhirter¹s company is the leading maker of CBA (copper, boron, azole) treated wood. It looks just like the old stuff, but is made with copper (to fight termites and decay) and boron (found in eyewash and mouthwash) instead of arsenic. Parr Lumber was the first Oregon company to stop using CCA wood and replace it with CBA from Washougal. Mike Jansen of Parr called poison control and asked for health advice after building his own raised vegetable bed with the arsenic-laced wood years ago. “They said wrap it with a 6 ml black poly plastic and keep your plants 6 inches from the edge. That should have told me something.” Jansen and Parr Lumber made the switch to CBA wood in June because “You’re dealing primarily with a biodegradable product… this stuff is found in a lot of products that are right in your kitchen.”
There’s also recycled wood lumber made with resin, plastic bags and
shrink wrap called “Trex”. Both CBA and Trex cost a little more than the
old stuff, but Jansen looks at it this way; “You’re talking about $1.68 more
for a 2×12 of CBA. But for the people who are concerned about their health or children that’s (sic) a small price to pay.”
So what should you do while the experts disagree about the health
risks? I’m not a chemist, but I can give you some advice.  Listen to
experts who have the background and understand chemistry but don’t have any money at stake. According to health officials, if you keep the CCA pressure treated wood in that raised garden bed you made. You very well may end up lying in it some day.