The RIC Good Wood Guide

Preservatives NOT Recommended

- from the RIC Good Wood Project & the Good Wood Advisory Centre, Vic.

(See also Toxic Substances - Flaws in Australian Regulations, below)


Some timbers need a preservative treatment to prevent attack by insects, termites and decay, especially when they come into contact with the ground, and for exteriors of structures in hot and humid weather. The two most frequently used preparations for treating pine against rot (fungus ) and insects are Copper Chrome Arsenic (CCA), and Light Organic Solvent Preservation (LOSP). The Good Wood Guide does not recommend either of these. Both CCA and LOSP will pollute the environment at several stages of their lifecycles (see below).

If you feel compelled to use one or the other of these, then CCA is the more environmentally benign of the two1, but LOSP may be preferable for applications such as joinery, where dimensional-stability is important.

The environment movement is still divided on whether or not using CCA or LOSP treated timber is better than using old growth forest hardwoods, but it is to be hoped that the issue can be looked at from the perspective of there being a lack of durable native softwood timbers available on the market and a lack of awareness of recycled and/or non-timber building alternatives2.

Ammoniacal Copper Quaternary Compound (ACQ)

ACQ is a more recent addition to the Australian preserved timber market. It is vaunted for its greater safety of storage and application than CCA, yet with similar performance ability. Its long-term performance is still an unknown, as is a safe means of disposal of discarded shavings, sawdust, offcuts, and end-of-life timber.

Copper Chrome Arsenic (CCA)

Please don't use this stuff! Try and change your plan of approach and use recycled or plantation-sourced hardwoods if you must have exposed timber3. If you must use non-durable hardwoods or softwoods, try and use them only for internal applications, where borax4 treatment and/or painting, will suffice to protect them.

This is the only way we will avoid the ever-escalating problem of how to dispose of CCA-treated timber at the end of its useful life. Even treated pine decays and has to be replaced sometime - usually after about 20 years of service-life. Burning or burying the discarded timber will pollute either the sky or the earth. Suggestions to use it as chicken litter or mulch around trees should be shunned! CCA-treated timber at the end of its useful life is toxic waste.

CSIRO experiments have indicated that 3.5 percent of arsenic from CCA is leached from the timber after one month of exposure to running water5. The CSIRO says that arsenic is not a cumulative poison, nor is it a primary carcinogen or mutagen, yet it apparently does make its presence felt in the ecosystem, where it can have a seriously adverse effect on aquatic lifeforms6. Also, the Radiata Pine Association claims that, "It has been conclusively established that once the preservative chemicals are fixed in the wood, no adverse effects occur as a consequence of handling, licking or occasional chewing of CCA-treated Radiata Pine".

This allows no consideration of the enormous problem of treated timber disposal, nor for residual CCA which is not fixed in the wood during the impregnation process. The Southern Sydney Regional Waste Planning & Management Board defines wood waste as: "Any untreated, uncontaminated wood waste material, including sawdust, timber shavings and offcuts, crates, pallets, packaging." They really do not want to know about chemically treated timbers when it comes to being able to re-use or reprocess them.

In 1995, the drinking water of Mount Gambier in South Australia was threatened when 40,000 litres of copper chrome arsenate solution spilled from a storage cylinder at a CSR softwood site. Fifteen thousand litres spilt into a nearby groundwater bore only four kilometres from the town's supply lake itself.

Sawdust from CCA-treated timber is also a biohazard for woodworkers7 and the environment. Nose bleeds, heaviness of the chest, itching and burning of the skin, and stomach pains are all possible symptoms of worker-exposure in the short term. Hazards from long-term exposure are an unknown, but they should be assumed to exist.


Creosote is generally regarded as being too toxic to be an environmentally-friendly choice. It is a heavy-duty timber preservative, usually used in industrial applications such as bridge-timbers and electricity poles. Traditonal creosote emits a vapour that can irritate the eyes and skin. A new creosote called PEC (pigment emulsified creosote) is a nasty chemical-cocktail made from coal tar, with the pigment used to stabilise it being a heavy metal. Despite being an improvement on traditional creosote in terms of performance, it is definitely not suitable for domestic or general building-applications. As for CCA, there are no universally acceptable methods for disposing of creosote-treated timber.

Light Organic Solvent Preservative (LOSP)

The LOSP preservative solution is intended to prevent fungal invasion of timber. It can contain such chemicals as tri-butyl tin oxide, copper naphthenate, zinc naphthenate or pentachlorophenol (PCP) - these combined with resin or wax to improve its retention in and increase the water repellency of the timber.

This is a solvent-based treatment, as opposed to CCA, which is water- or oil-based. LOSP-treated timbers are designed primarily for external building situations (eg, decking, fencing, outdoor furniture, etc). It is suitable for above-ground applications only where dimensional-stability is important, such as joinery. Unlike CCA's, the LOSP's do not chemically fix in the wood structure and would leach into the soil if used for inground applications. LOSP-treated timbers should not be used for inground applications. LOSP cannot be used for applications such as food cupboards, unless the LOSP formulation is of low toxicity8.

If you insist on using LOSP, a post-protection treatment such as Organoil, or Livos or Bio Paint should be applied9. Where treated timber has been cut or drilled, the exposed surface should be treated in this way.

Please Note: LOSP-treated timber often contains hazardous PCP (penta-chlorophenol), or TBTO (tri-butyltin oxide1). Another problem with LOSP is that, for every cubic metre of timber treated, the result is 30-40 litres of hydrocarbon solvent evaporating into the atmosphere. LOSP-treated Radiata Pine is also known as SuraPine, Vasol-treated Pine, or Protim-treated Pine.

Oil Paints, Plastic Paints, Varnishes

These can give off traces of toxic fumes for months or years which can produce symptoms of illness in sensitive people. Most likely to contaminate the atmosphere are epoxy paints and varnishes, baked enamels, shellac, lacquers, linseed oil paint, paste waxes, urethane varnish and latex paints. Admittedly, things are slowly changing, as witnessed by the new trend to non-toxic and low-fuming paints10.

Pentachlorophenol (PCP)

PCP (derived from sodium pentachlorophenate) is a wood preservative of the organochlorine family. It is part of the same chemical group as DDT and Agent Orange. Although linked to long term health problems in timber workers, it is still registered for use in Australia although it was deregistered by New Zealand health authorities in 199011. PCP can cause persistent fever, fatigue, weight loss and nausea. PCP dioxins can also cause birth defects, allergies or cancer. Being an organochlorine, it is persistent in the environment, and can be passed on to successive generations through sperm and breast milk.

PCP is classified as a 'Schedule X Waste', and cannot be disposed of without special technology and/or facilities. PCP is an unknown in that no-one seems to know or is unwilling to divulge exactly who in the Australian timber industry is still using it. Needless to say, the Good Wood Guide suggests you keep well away from PCP and all organochlorine chemicals and demand that their use be banned.

Toxic Substances - Flaws in Australian Regulations

Australian governments fall far behind European countries and the USA in our regulation of toxic substances. Australian data collection is inconsistent and focused on only a handful of chemicals. The general thrust of Australian regulations is not to minimise pollution, but to hide or legitimise it. Australian solutions to date have followed a substance-by-substance approach, which is fundamentally flawed because it deals only with a chemical after it has become a public problem. This approach is underpinned by a wait-and-see attitude - we wait for problems to occur before doing anything about them...

Agricultural chemical regulation is just as haphazard. There are no systems in Australia for collecting information on the volume of chemicals used in the agricultural context, or for monitoring their effects on humans and the environment.

- Greenpeace12 Australia News - autumn, 1995.

1. Make the Right Choice in Timber - Wilderness Society

2. See the article Reducing Demand for Timber, and Non Timber Building Materials in the Directory.

3. Despite industry inferences otherwise, CCA treated timber is not zero-maintenance, and should really be painted anyway when exposed to the weather, otherwise it is not really protected.

4. Borax is a naturally occurring mineral salt, available from chemists and hardware stores.

5. CCA has been proven deadly to marine organisms by researchers at Rutgers University. NB: French scientists have discovered a bacteria that can convert the arsenic in polluted water to a less toxic substance which at least bodes well for aiding safe disposal of waste CCA-treated timber which gets dumped in landfills.

6. The CSIRO says oil-based CCA treatments leach twice as slowly as water-based ones and also give more resistance to moisture.

7. See Take Care if You Use Treated Timber. Also, a US company, Earth Choice Forest Products, markets a range of wood products which are pressure-treated with preservatives which do not contain any toxic arsenic or chromium - see Timber, Uncertified, in the Directory.

8. See Point 1, above.

9. See Non Toxic Paints, Treatments.

10. See the articles Low Toxic Petrochemical Paints, and House Paint - A Gloss Over.

11. Refer to the book, The Plantation Effect (under Books, Ethical Timber, in the Directory), about the devastating contamination of New Zealand waterways by PCP and other organochlorine chemicals.

12. See Conservation Groups in the Alternative Directory

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