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 Use of CCA wood preservatives and CCA-treated timber

A Wood Protection Association Guidance Note


This Guidance Note is issued by the Wood Protection Association (WPA) to assist users of chromated copper arsenate (CCA) preservatives and users and specifiers of CCA-treated timber to understand changes in UK law brought in to implement the provisions of EU directive 2003/2/EC (“the Directive”)...

 The UK regulations are The Environmental Protection (Controls on Dangerous Substances) Regulations 2003, SI 2003/3274 and The Marketing and Use of Dangerous Substances (No. 4) Regulations (Northern Ireland) 2003, SR 2003/548 (“the Regulations”).  

The Regulations bring in improved safety rules on the sale and use of CCA wood preservatives and CCA-treated wood and wood-based products. The Wood Protection Association (WPA) and its members afford the safety of the public and people working in the industry the utmost importance and fully support the principles and objectives set out in the Regulations. To this end, association members have already brought in changes to preservative supply and treatment practices that will facilitate compliance with the Regulations well before they come into force. The WPA is not aware of any impact on human health from proper use, handling or disposal of CCA preservatives and CCA-treated timber.

Treated wood already in use not affected

The Regulations do not apply to CCA-treated wood already in place. This mirrors the position in the USA where the Environmental Protection Agency has advised there is no reason to remove or replace existing CCA-treated structures, including decks or playground equipment. This is now supported by the US Consumer Product Safety Commission, which has recommended that no further action be taken to regulate wood treated with CCA.

History of CCA

CCA preservatives were developed in 1933 and have been used extensively in all parts of the world, facilitating the use of local and imported timber in situations where timber could otherwise not have been used due to fungal, beetle, termite or marine borer attack. In many such situations if CCA had not been available concrete, steel, aluminium or plastic may have had to be used with loss of visual appeal and potential adverse environmental impact.

Wood as the sustainable construction material

In its response to the consultation on the Directive in its draft form, the WPA made the point that it is important to ensure the continued and increased use of wood as the only truly sustainable construction material. CCA treatment has ensured the acceptability of sustainable wood species in both ground and water contact as well as above ground uses at risk of insect and fungal attack due to its highly cost-effective properties. Confidence in the durability of these otherwise perishable commercially available timber species has allowed wood to be used in such end uses as road fencing, environmental barriers, ground engineering and retaining structures where at least 30 years service 2

life is required. Many other end uses with very long service life requirements are also served by CCA-treated timber.

Transition to alternative preservatives

Wood preservatives formulated without arsenic are available and performance of treated timber in many uses, including construction, is excellent. A list of suppliers of such preservatives is available from the WPA. Wood preservative suppliers have devoted years of research and development and invested a great deal of money in programmes to develop new products that offer timber treaters and their customers a choice. This is evidence of a responsible industry ahead of, not following, the evolution of society’s attitudes to health, safety and environmental protection.

Most treatment companies in the UK have already introduced non-arsenic based treatment into their range and this trend can be expected to continue.

Provisions of the Regulations

Key changes to the use of CCA wood preservatives and CCA-treated timber with effect from 30 June 2004 include:

The preservative itself must be CCA Type C.

The Regulations lack a definition of ‘Type C’. The WPA has submitted to HSE for approval a definition of a ‘Type C’ CCA preservative that includes the formulations normally supplied in the UK complying with BS 4072. The WPA understands this has been accepted. The WPA foresees no change in the type of CCA preservatives available on the UK market as a consequence of the Regulations. These products are used diluted with water and the diluted solution typically contains no more than 3% preservative ingredients with 97% or more water.

Freshly treated wood must not be placed on the market before fixation of the preservative is completed.

‘Fixation’ describes the reactions that take place in the wood after impregnation leading to the CCA components becoming ‘fixed’. It is this feature that makes CCA such a long-lasting treatment with minimum environmental impact: for example CCA-treated wood has been used in cooling towers under continuous water flow giving in excess of 25 years service.

Current conditions of consent for CCA preservatives under the Control of Pesticides Regulations include a requirement that treated wood must be held for at least 48 hours after treatment and until surfaces are dry within a bunded area on a site which is maintained to prevent loss of treatment product to the environment. The statutory minimum period may be reduced subject to managed fixation methods such as post treatment heating to accelerate drying and fixation reactions. Compliance with these conditions is expected to satisfy the Regulation’s requirements on fixation.

‘Placed on the market’. The WPA is advised by the UK Department for Environment Food and Rural Affairs that ‘placed on the market’ includes offering for sale or supply so, for example, a supplier of treated wood should not, from 30 June 2004, list in a catalogue or have in stock for sale CCA-treated wood intended for use by professional or industrial users in one of the restricted end-use categories (see below) or by the public.

CCA-treated wood may be placed on the market for professional and industrial use 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. The Regulations lists the following uses:


• as structural timber in public and agricultural buildings, office buildings, and industrial premises; • in bridges and bridgework; • as constructional timber in freshwater areas and brackish waters e.g. jetties and bridges; • as noise barriers; • in avalanche control; • in highway safety fencing and barriers; • as debarked round conifer livestock fence posts; • in earth retaining structures; • as electric power transmission and telecommunications poles; • as underground railway sleepers.

The WPA’s opinion is that compliance with the caveats (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) automatically follows from inclusion in this list. No further assessment of compliance is necessary.

See above for interpretation of ‘placed on the market’. Note the restriction for ‘professional and industrial’ use – CCA-treated timber should not be placed on the market for DIY use.

However, CCA-treated wood may not be used: • in residential or domestic constructions, whatever the purpose; • in any application where there is a risk of repeated skin contact; • in marine waters; • for agricultural purposes other than for livestock fence posts and structural uses (in accordance with the previous paragraph dealing with permitted uses); • in any application where the treated wood may come into contact with intermediate or finished products intended for human and/or animal consumption.

‘Repeated skin contact’ is not defined in the Regulations but the Department of Trade and Industry has given a helpful definition of ‘frequent’ skin contact in their guidance notes on other regulations that introduced restrictions on creosote-treated timber. This suggests that someone working with treated timber and handling it without gloves is an example of someone in frequent skin contact. This may give an indication of what is meant by repeated skin contact.

Advice for users of CCA-treated timber

It is clearly the user’s responsibility to comply with the law when the Regulations come into force in the UK. However, the WPA advises suppliers of CCA-treated timber to provide purchasers with information on allowed and restricted uses and when restrictions come into force. Sale or supply to the public for DIY use from 30 June 2004 will not be permitted. CCA-treated timber intended for use in one of the prohibited categories and in stock on 30 June may not be so used from that date. For such material, the preferred option is for it to be used instead in one of the permitted categories but if that cannot be achieved then it must be disposed of as hazardous waste. Contact the WPA for advice on disposal options. The WPA advises suppliers to convey information on allowed and restricted uses as set out in the Regulations (see above).

CCA-treated wood must be individually labelled For professional and industrial installation and use only, contains arsenic”. In addition, all wood placed on the market in packs shall also bear a label stating, “Wear gloves when handling this wood. Wear a dust mask and eye protection when cutting or otherwise crafting this wood. Waste from this wood shall be treated as hazardous by an authorised undertaking”.


DEFRA advises that labelling rules will apply to all parts of the supply chain so a supplier receiving treated timber in a labelled pack and who intends to supply smaller quantities by breaking the pack must ensure that the individual labelling requirement is met.

Since CCA-treated wood placed on the market and used before 30 June 2004 can legally be used in any situation by all types of users, applying the provisions for individual labelling now may be inappropriate unless a supplier wished to comply ahead of the legal date. An option could be to add the phrase ‘(Use restriction effective from 30 June 2004)’ to the individual label wording. Point-of-sale material can also usefully add to the information available to a user and can include helpful guidance and information beyond that strictly required by the Regulations. However, the WPA advises suppliers to begin labelling packs to ensure, so far as possible, that CCA-treated timber in packs already on the market on 30 June 2004 is appropriately labelled. Suppliers who intend to continue to supply CCA-treated timber for professional and industrial use should make provision for labelling individual pieces so that stock is appropriately labelled from 30 June 2004.

This Guidance Note provides the WPA’s opinion on the Regulations. Companies and individuals are advised to seek advice from their own legal advisors if they are in any doubt as to the application of the WPA’s opinion to their own situation. The WPA, its employees and officers cannot be held liable for any loss or liability arising from reliance on this guidance document which is nevertheless offered in good faith.

The WPA continues to seek official guidance and interpretation from the UK government departments responsible for implementation of the Regulations. These include the Health and Safety Executive and the Department for Environment, Food and Rural Affairs.

Further information will be available from the WPA in printed and electronic form and from the association’s website www.wood-protection.org

For further information please contact:

Dr C R Coggins


British Wood Preserving and Damp-proofing Association

1 Gleneagles House


Derby DE1 1UP

Tel 01332 225100

Fax 01332 225101

Email crc@bwpda.co.uk © BWPDA January 2006

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