Raised bed question in GYO

[sweetcorn]

In last month's GYO there was a question about arsenic leaching from tanalised timber into raised beds. I want to install raised beds and have done lots of research into this - I have been told that timber treated with Tanalith (which most people treat timber with now), does not have arsenic in it!

Even HDRA Ryton is not flagging up a problem

Anyone else know anything about this? The answer in GYO seems to imply that the only way you can do raised beds safely is with Linkaboard (v. expensive!).

[Alison]

I raised this question a few weeks ago and was told (think it was Pigletwillie) that the constituent mix of what ever they use to tanalise changed about 10 years ago and is now fine. My concern is that we built our raised beds almost that long ago and could have had old stock wood which could mean that it contains the nasties. The GYO article seemed to indicate that I could dig out the soil and line the wood rather than rebuild but this would be quite a major activity as they are deep beds so I'm not too sure what to do although will be planting further away from the edges this summer.

[sweetcorn]

I hope you are right, cos it's a nuisance having to plant away from the edges or line them, and also I am always conscious of trying to be organic, (even if I don't always succeed!) and not eating the rubbish that commercial growers liberally spray all over their food!!!

I am thinking of buying timber from a local merchants who uses Tanalith.

[carlseawolf]

i used treated wood for my raised beds and lined them with plastic sheet , this was not done because of what was put on the wood but to keep the soil and wood seperate so it does not rot .

[sweetcorn]

What sort of plastic? Doesn't it go brittle? Sounds like a good idea, but would like to know how long it would last.

[carlseawolf]

the plastic is just general building clear plastic ( thick stuff) and its not uv stabilized but it doesn't have to been as only 4" will be seen at the top of the bed .
is it brittle or how lomg it lasts no idea they have only been in 3 months so no time scale to go by.

[pigletwillie]

The main nasties in the old tanalised timber were copper and Arsenic.

Whilst you can get it leach out over time, the amounts are very limited. Most of the arsenic gets released if it is burnt which is why you should never burn it in an open fire or use off cuts as kindling.

I would be more concerned about creosote and such things.

[wildinthecountry]

Chris Beardshaw was talking about this on Beechcroft Garden on BBC2 this morning. He said root vegs are particularly susceptible to taking in the chemicals used in treated timber so the beds should be lined with plastic. Oh heck, we've just bordered all our beds to keep the paths tidy. Including the potatoes.:-(

[Bill HH]

It seems to be in vogue to panic at the mere thought of even the mildest contamination. People have been using this sort of stuff for 50 years, particularly creosote. I cut my teeth on off cuts of wood sodden with the stuff. Just because some scientists in Minnisota finds one rat in ten thousand has a boil on its nose seems to mean we all have to abandon practises that have served us well for many years. I am healthily unmoved by all this. Arsenic is used in medicine so it may even be doing you good. Others may disagree


Oh and I doubt if lining wood with plastic will help stop it rotting, quite the reverse, it will trap moisture and make things worse.

[mothhawk]

The following quote is from the Straight Dope site The Straight Dope: Is the arsenic in treated wood dangerous?

"Be warned, though: one thing you don't want to do is try to get rid of CCA-treated wood by burning it or sawing it up. Although reports of environmental arsenic poisoning are rare, those we do see often involve dust, ash, or the like from sawn or incinerated CCA-treated wood. One case involved a rural Wisconsin family that suffered a scary list of ailments including epileptic seizures, seasonal baldness, rashes, diarrhea, headaches, bronchitis, and blackouts. They were lucky nobody died — the arsenic level in some of their hair samples was found to be more than 100 times normal. Turned out they'd been burning CCA-treated lumber scraps in their wood stove for three years."

[Bill HH]

The following quote is from the Straight Dope site The Straight Dope: Is the arsenic in treated wood dangerous?

"Be warned, though: one thing you don't want to do is try to get rid of CCA-treated wood by burning it or sawing it up. Although reports of environmental arsenic poisoning are rare, those we do see often involve dust, ash, or the like from sawn or incinerated CCA-treated wood. One case involved a rural Wisconsin family that suffered a scary list of ailments including epileptic seizures, seasonal baldness, rashes, diarrhea, headaches, bronchitis, and blackouts. They were lucky nobody died — the arsenic level in some of their hair samples was found to be more than 100 times normal. Turned out they'd been burning CCA-treated lumber scraps in their wood stove for three years."

Further to that, we used to get a lot of old telegraph poles for gate posts and building sheds, the supplier warned us not to burn the part that had been in the ground because that was treated with arsenic. As for the Wisconsin family I reckon I have most of those symptoms apart from the epileptic seizures, maybe thats next on the list.

[alldigging]

Chris Beardshaw was talking about this on Beechcroft Garden on BBC2 this morning. He said root vegs are particularly susceptible to taking in the chemicals used in treated timber so the beds should be lined with plastic. Oh heck, we've just bordered all our beds to keep the paths tidy. Including the potatoes.:-(

Indeed.
The man at creocote told me he wouldn't have it near his veggies!

He reckoned it didn't travel far through the soil though so wouldn't affect neighbouring plots.

Another reason to be careful about accepting veg from other people's plots.

[meteor]

Just got a load of scaffold planks to create raised beds in my new polytunnel and reading through this thread has me a little concerned. Can any recommend a safe perservative to use on them?

[petebetros]

I'm tempted to get untreated wood to use more as an edging rather than proper raised beds and replace it every couple of years. A quick trip to Wickes and each 10x4 foot bed would cost about £8 each to edge with 15 cm wide boards.