General Discussion:

Cedar Retaining Walls-health risks?

Messages posted to thread:

Rachel21-Jan-04 03:01 PM EST 8   
Susan21-Jan-04 05:52 PM EST 6a   
GlenT21-Jan-04 10:24 PM EST 7   
Susan22-Jan-04 04:03 AM EST 6a   
Rachel in BC22-Jan-04 11:56 AM EST 8   
garth22-Jan-04 06:13 PM EST 2b   
Rachel in BC23-Jan-04 12:27 PM EST 8   

Subject: Cedar Retaining Walls-health risks?
From: Rachel
Zone: 8
Date: 21-Jan-04 03:01 PM EST

Hi there, I'm creating a new vege garden and want build it as a raised bed area using cedar planks to hold the soil, but I have reservations about using cedar around edibles. Is anyone out there able to steer me in the right direction? I have heard horor stories about using pressure treated wood with edibles, and so I know that that is a no-no, but I have also heard that cedar chips are not the ideal mulching agent & I was wondering if the reason for this is a chemical which they may leach out. Help. Thanks Rachel in BC

Subject: RE: Cedar Retaining Walls-health risks?
From: Susan
Zone: 6a
Date: 21-Jan-04 05:52 PM EST

Interesting question... Cedar contains a chemical that gives it insecticidal properties - it's the reason why it's used for closets, cedar chests for clothes storage etc. The plicatic acid it contains causes asthma and is a problem for sawmill workers (and for some animals when cedar chips are used for bedding....) Western red cedar has the highest concentration although it is also present in white cedar. A similar but different acid is present in pine. I can find no information on whether the acid is taken up by plants but you might find the information at:

interesting. It's an American college web page - I hope it is accurate but one can never be entirely sure.... The article deals only with mulches not solid wood so it's hard to say whether it's relevant or not.

Subject: RE: Cedar Retaining Walls-health risks?
From: GlenT
Zone: 7
Date: 21-Jan-04 10:24 PM EST

Rachel-like Susan says, interesting question.

I was on a tour of a large perennial grower here, and they discussed the bark in their growing mix. Apparently cedar is now used freely, where it previously had been assumed to be toxic to plants. I seem to remember them saying cedar products were actually beneficial as it turns the plants, roots anyway.

The other thing I've noticed is that salmon here is sometimes cooked at "fine" restaurants on a piece of cedar, to give it a different taste. I wonder if they've researched the safety of this.

Personally I'd much sooner have cedar around my veggies than any kind of treated lumber, but really don't know if there's anything toxic to humans in the stuff. Hopefully somebody here has the final word on this one!


Subject: RE: Cedar Retaining Walls-health risks?
From: Susan
Zone: 6a
Date: 22-Jan-04 04:03 AM EST

I was thinking overnight about this question and the information on that web page I listed. In summer 2000, we laid pine bark mulch paths throughout the garden. Our dog, a Golden Retriever, liked to lay on it in the shade under the trees. By the fall, she had a severe case of asthma and we didn't know what had caused it. It was so severe that, looking at the x-rays, the vet thought lung cancer was an equally likely explanation of her problem! She had a horrible cough and was hacking up great gobs of slimey goo! She was put on bronchiodilators and by spring she was fine and it's never come back. After reading that information, I assume it was the pine mulch that triggered it and that the acid that causes it leached out of the mulch by the next spring and therefore was no longer a problem.

Glen - my husband cooks salmon on cedar slabs too - those slabs are supposed to be soaked in water each time (otherwise, presumably, they'd catch fire!) Maybe the soaking leaches out anything that would cause problems.

I was intending to lay a new layer of pine mulch on my paths this spring but I don't think I will now. My dog will be 13 this summer and another bout of asthma would not be good at her age!

Rachel - my conclusion, after thinking about all this, is that if there is a risk it is probably easily addressed by letting the boards age for a year - e.g. build your beds but plant something else in them this year - by next year, anything dangerous would probably have leached out and broken down if the fact that my dog was not bothered by the stuff the next year is any indication. (The acid in pine and cedar is different but I would hope that the same might be true of both given the use of cedar in cooking....) If you have a choice, use white cedar not red as white contains less of the problem acid. If whoever is cutting the boards to make the beds is prone to asthma, it might be a good idea to wear a dust mask.

Subject: RE: Cedar Retaining Walls-health risks?
From: Rachel in BC
Zone: 8
Date: 22-Jan-04 11:56 AM EST

Hi Susan and Glen, ( and everyone else, too, of course.) Thanks for such informative responses. I'm sorry to hear about your dog, Susan, but glad to hear that she is doing better. That was a good website you referred me to - some really interesting stuff there - especially seeing as my hubby runs a small sawmill, and cuts mainly cedar. I knew that it could cause adverse reactions in some people, but he seems not to be one of them thankfully. But as there was mention of indications of possible links to certain cancers on that website I am now going to be looking into things a little deeper! Now that you mention it, I , too, have seen those cedar slabs for sale on EBay - "genuine smoked flavour" or some such pitch. They were asking $10 for a foot long piece of roughcut 1x10! Talk about making a profit!!! So if people are cooking on cedar slabs it makes me feel a lot more comfortable about edging a bed with it. The boards will be made from old growth cedar which has been dead for years - the kind that cedar shakes and shingles are cut from as these boards are coming from the sawlogs from the remainder of those trees. So I think that if the wood itself is not toxic - I should be fine. Again, thanks for all of your help. Happy gardening. Rachel in BC

Subject: RE: Cedar Retaining Walls-health risks?
From: garth
Zone: 2b
Date: 22-Jan-04 06:13 PM EST

Hi Rachel If you have health concerns about any type of material used for raised beds why not just line the inside walls with heavy mil plastic sheeting. A roll is fairly inexpensive and all you need to do is staple it up, fill with your soil mix and away you go never having to worry about anything leaching into the soil and contaminating your veggies

Subject: RE: Cedar Retaining Walls-health risks?
From: Rachel in BC
Zone: 8
Date: 23-Jan-04 12:27 PM EST

Good idea Garth. I could simply line the walls, but I'd still rather know of any potential hazards from using cedar. Thanks.

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