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Is it safe to use treated wood for raised bed gardens?

Marjory WildcraftMarjory Wildcraft ✭✭✭Posts: 986 admin
edited October 2020 in Other News

The answer to that question used to be a solid "no", but I recently came across this post by The Natural Handyman who says the old chemicals used before are not in use now. And it's safe to use pressure treated lumber.

The Natural Handyman says: until 2003, the most common preservative used for pressure treated wood was chromated copper arsenate (CCA), a compound using arsenic as its primary rot protectant. Over years, the industry, in cooperation with government recommendations, phased out the use of CCA for all residential and most commercial wood pressure treatment. Part of the reason was the fear that the arsenic would poison the soil and anyone who touched it. Though actual cases of poisoning via pressure treated wood use by the public were hard to find, there was enough circumstantial evidence of soil contamination to warrant a change.

Here is the rest of the post:


  • toreytorey Posts: 2,336 admin

    There is still a lot of that CCA wood out there in use on decks, fences, gazebos and other projects. This wood is extremely dangerous when burned. Firefighters (at least in my area) have been cautioned about exposure when attending fires that may contain large amounts of CCA treated wood. High concentrations of arsenic can be found in the ash. So, please don't burn any CCA treated wood. Mark it and send to a hazardous materials waste site. If you have to cut this wood for any reason, make sure you are wearing proper PPE.

    This is a link to the SDS sheet for CCA. https://www.koppersperformancechemicals.com/sds/pdf/cca-sds-english.pdf

    This is a link to a case study of a family who suffered with extremes symptoms of arsenic poisoning from using CCA scrap wood as a heating source. https://www.nap.edu/read/4795/chapter/14

    This is a link to an article that states 1 Tbsp of ash from CCA treated wood is enough to be lethal to humans. http://www.noccawood.ca/docs/cca_wood_ash.html

    If you are buying newer, pressure treated wood, check to see which preservative type products have been used in the manufacturing process. Some pressure treated wood is being treated with pesticides (to reduce damage by insects) and herbicides (to reduce damage by invasive weeds). I don't think we want either of those in our food gardens if we are growing organically. Caveat emptor!

  • Lisa KLisa K Posts: 413 ✭✭✭✭✭

    I think I will stick to untreated cedar or redwood even if I have to replace them every few years. But yet cinder blocks.

  • monica197monica197 Posts: 542 ✭✭✭

    The stuff sounds so dangerous.

  • WendyWendy Posts: 106 ✭✭✭

    I use untreated wood, and yes, they need to be replaced every 5 years or so. I don't like having to guess what is in the wood and if it might be leaking into my soil.

  • gardneto76gardneto76 Posts: 254 ✭✭✭

    I have always used untreated wood, then applying linseed oil to the outside of the bed after it is built. This is to help protect it from the intense sun here in Phoenix. I built a compost bin and it has lasted several years. I forgot to treat the boards that separate the bins and they will need to be replaced this year, but the outside is doing amazing still 5+ years later.

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