Is tanalised wood safe for veg growing?

[Growem]

Can I just repeat that in pressure treated/tanalised boards that you buy nowadays in the UK, there is NO arsenic in them. None. So the point of whether it does damage or not is moot.

[GardeningMike]

Tanalised wood in UK is arsenic free...

Can I just repeat that in pressure treated/tanalised boards that you buy nowadays in the UK, there is NO arsenic in them. None. So the point of whether it does damage or not is moot.

Many thanks for this Growem - it's good to be brought up to date! I am clearly out of date here. In addition, I think I need to read some of the threads more closely! May well be that they don't use arsenic in France either now in tanalised wood, and anyway even if they did it seems the UK have moved on, which, given the element of doubt is probably just as well. Anything at all on the toxicity of the asenic free products, or wood treated with them?

[rob the roller]

The information on exclusion of arsenic from talalised wood is helpful, but when did the exclusion become law, and what is the likelihood that old timber such as scaffold boards being recycled in the garden does not contain arsenic? Is there a simple test?

[teakdesk]

Tanalised CCA wood products are made in Australia by Koppers Arch Wood Protection (Aust) Pty Limited.

CCA stands for Copper Cromium Arsenic.

The following is taken from their data sheet.

Q/ Hasn’t CCA been banned in many countries?
A/ A European Union marketing directive limiting CCA treated wood products to a range of industrial uses became effective from July 2004.

Q/ Can exposure to CCA treated wood cause cancer?
A/ While arsenic and some forms of chromium are regarded as capable of causing cancer in humans, exposure to CCA treated wood has not been shown to cause cancer.

Q/ I have heard that arsenic can still leach from treated wood. Is this true?
A/ while it is true that some leaching may occur (as it can with any treated timber and many other materials), the actual relative scale of leaching is very low and is very unlikely to pose environmental or health risks in normal situations.

Q/ Can I use TANALISED® CCA around food, water, vegetables or other plants, pets and animals?
A/ The CCA preservative is leach resistant because it becomes “fixed” within the wood as a result of complex reactions after the treatment. Thus CCA treated timber is suitable for raised flower or vegetable beds, landscaping, mushroom trays, grape and tomato stakes, greenhouse uses and similar applications. Scientific studies have shown that the CCA constituents should not occur in foods produced in this manner at significantly higher levels than are naturally present.

Their safety instructions include....
Wear a mask when sawing tanalised CCA wood and do not inhale dust
DO NOT BURN.



I do not know if scaffold boards are called "industrial" by the EU or not (ie whether they are still allowed to be treated with CCA in the EU) so I cannot tell you whether new or old boards are likely to have arsenic.

However, I would be very careful sawing them and never burn any.

New boards from B&Q will not contain arsenic but you should still not breathe the sawdust or burn offcuts.




I should add that Tanalising is carried out with chemicals other than CCA.

For instance, from www.tanalised.com: TANALISED E pressure treated timber has been impregnated with TANALITH E, a waterborne product based on copper triazole technology.

Copper is derived from recycled sources and triazoles are organic biodegradable biocides, commonly used to protect many of the food crops we eat.

TANALISED E pressure treated timber is usually specified for both in and out of ground contact applications where there is a medium to high risk of decay or insect attack.

[Demeter]

I do not know if scaffold boards are called "industrial" by the EU or not (ie whether they are still allowed to be treated with CCA in the EU) so I cannot tell you whether new or old boards are likely to have arsenic.

The industrial applications where arsenic can be used are VERY limited. It is only allowed where "the structural integrity of the wood is required for human or livestock safety and skin contact by the general public during its service life is unlikely" and even then there are a host of other conditions. In particular it is not allowed (in the UK) if there is "a risk of repeated skin contact". This would rule out scaffold boards. Also, wood treated with arsenic is to be treated as hazardous waste so if Joe Public can get their hands on it then this would indicate that it can't have arsenic in it!

There are probably lots of pre-regulations scaffold boards around the place but if they are being sold second hand or even given away now then they should not have arsenic in them.

PS the UK regs came into force in 2007, the 2004 date is I assume the date of the underlying EU directive.
http://www.opsi.gov.uk/si/si2006/20063311.htm

[Peter]

.....Also I've recently planted an almond tree and, looking up its preferred location etc on Google, was surprised to learn almond nuts (and many other nuts) contain traces of arsenic... - it's evidently what gives almond paste on the Christmas cake its special flavour, yikes! Further searching provided the usual contrary opinions, one source saying it was a non-toxic form of arsenic, another that if you ate 500 fresh almonds you'd be dead (from arsenic poisoning rather than indigestion...). ....

Errm, it is Cyanide that is found in Almonds and similar stone fruit kernels. I think there is a similar posion issue with apple pips, but you would have to eat a sackful.

Cyanide or Prussic Acid as the older Detective fiction writers used to refer to it is invariably described as "smelling like almonds".

[COMPOST CORNER]

Cyanide itself is, I am led to believe, odourless, and it is the reaction of the Cyanide with human or animal tissue that causes the almond like smell. This could be an urban myth, but I seem to remember it being on a serious forensics show, rather than a detective story.

[bockchung]

Hmmm, toxic chemicals with your food?

"The American magazine 'Organic Gardening' has been leading the fight against using pressure treated timber in the garden for the last few years. They often refer to scientific research showing that CCA treated timber leaches arsenic and chromium into the soil. And from the soil it goes into your homegrown vegetables and then according to OG into you"

Source: Wood Preservatives & The Organic Standards Covering their Use


"Tanalised, pressure treated or CCA timber are all terms for a wood
preservative system based on copper, chrome and arsenic. For years we at HDRA
have advised our members not to use tanalised timber to edge vegetable beds
and make compost boxes, simply because we felt that the chrome, a toxic heavy
metal, and arsenic, a poison used in the preservative had no place in an organic
garden

These worries were confirmed in spring 1997 by alarming reports from the
USA. Researchers found that decks made from tanalised timber can leach high
amounts of arsenic into nearby soil. Samples taken from beneath treated
decking contained up to 80 times more arsenic than surrounding soil and as much
as 35 times the legal limit for arsenic in the soil. The study found that arsenic leaches quickly from treated wood..."

[chris]

Have you checked the date from that source? Arsenic is no longer used in the process.

[Potstubsdustbins]

I happen to do work for a major timber company with a branch here in Nottm. As their tanalising plant is here in Nottm I asked the question about two years ago before building my pea containers.

The operator took me round the plant, showed me the chemicals, prohibition/safety notices etc. There is no arsenic used in the process what so ever it has been banned for a number of years.

Colin

[snakeshack]

interestingly arsenic smells garlicy cyanide smells of almonds,spag bol and christmas cake anyone?