I'd prefer the Old Lace

May 21, 2009 11:31 AM

Are my pressure-treated raised vegetable beds permanently toxic?

We have, let's just call them 'tenant farmers'. They've setting up vegetable gardens for us, in exchange for reduced rent. We have some raised beds that were there when we moved in 8 years ago which we have used a little for crops in past years. This year they filled them up with 2 yards of compost and planted lots of things there. Then they were alerted to the fact that the wood is CCA pressure-treated lumber. They won't go near them, won't eat any food grown in them, and advise us not to eat any either.

So I've been looking into sites like this, and I'm thinking I'm not too worried. I see from previous questions here that the general consensus is that I should be. I also looked at the MDSS, and that says I might get higher As levels in produce from the grocery store. (As long as I don't burn or lick the stuff.)

Details- The tags on the wood say Wolmanized- Ground Contact (.40), and have a date of 1993. They probably have been in place since 93 to 95. The beds are about 1'x12' and are either 6" or 12" high, and filled to the top. The compost is of '09 vintage.

Do you think chemicals would still be leaching into the new compost? If you think the beds are hazardous, is the new compost hazardous as well? (It's been in the beds less than a month.) Could it be removed and used elswhere? If I were to replace the boards, would the site still permanently damaged?

posted by MtDewd to home & garden (9 comments total)

Common sense precautions from the makers of Wolmanized wood has some bits about keeping it away from food. It wasn't the best choice for bedding.
posted by Cool Papa Bell at 11:47 AM on May 21

I'd err on the side of safety and ask your local cooperative extension service about the availability of soil testing for heavy metals in the bed areas. Wouldn't be inclined to eat the produce or reuse the compost without negative test results.
posted by vers at 12:10 PM on May 21 [1 favorite]

From what I've read, the risks of getting much more than a background dose of arsenic from pressure treated wood is pretty minimal, as long as it's generally intact and you have soil of a normal pH.

If you're really concerned, you can staple sheets of poly to the inside of the bed, or dig it out and paint the wood with several coats of latex paint.
posted by electroboy at 12:32 PM on May 21

According to Wikipedia, Wolmanized wood is not the same as CCA-treated wood, and contains no Arsenic. You may still not want to eat it, of course.
posted by goingonit at 12:33 PM on May 21

It also says CCA on the label.
posted by MtDewd at 2:00 PM on May 21

A friend of mine is going through this right now. He actually paid for a soil test, found arsenic and I believe heavy metals in the soil, and is ripping out all the beds and planning to replace them and the soil. Sad.
posted by serazin at 10:19 PM on May 21

A comprehensive soil test is really the only way to figure out what's actually in your soil. If you're truly worried spend the cash and figure it out. And don't use the state of the plants that may be growing there as a barometer of safety. Most plants can accumulate toxic amounts of heavy metals in their cell walls with no detriment to the plant as a whole.
posted by ZaneJ. at 12:37 AM on May 22

Have you also considered that this is a convenient excuse not to do the gardening?
posted by electroboy at 6:59 AM on May 22

That's what the tenant farmers are for.

We're going to get the soil tested and then see what the results are.
Thanks all.
posted by MtDewd at 11:53 AM on May 22