Photograph showing a raised boardwalk constructed from CCA-treated timber entering a forest

A boardwalk constructed from CCA-treated timber

The facts about CCA-treated timber

This comprehensive fact sheet provides consumers with up-to-date information and advice about timber treated with Australia’s most widely used wood preservative, copper chromium arsenic (CCA).

  • 28 October 2008 | Updated 14 October 2011

Restrictions and regulations

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Copper chromium arsenic (CCA) is Australia's most widely used wood preservative.

It has been used safely in Australia for 50 years and some 120 treatment plants are currently operating around the country.

CCA treatment is effective - for example, extending the life of a radiata pine post from a few years to 40 years or more - and relatively inexpensive.

Partial or complete restriction of CCA occurs in a number of countries including Japan, Indonesia, Sweden and Germany. In the USA, CCA cannot be used in the domestic or home markets.

In Australia, CCA preservatives are regulated by the Australian Pesticides and Veterinary Medicines Authority (APVMA). The APVMA implemented a number of restrictions on CCA that became effective in March 2006. The main implementation affecting the public is that CCA is no longer used to treat timber for structures where there is frequent and intimate contact, such as playground equipment, picnic tables, handrails, decking boards, garden furniture and exterior seating.

The main concern with CCA is that it contains arsenic. While not a mutagen, arsenic acts as a carcinogen when ingested at rates above certain tolerable limits. It may initiate skin and liver cancers.

The APVMA implemented a number of restrictions on CCA that became effective in March 2006.

The safe or tolerable amounts of arsenic that can be ingested by humans have been accurately determined because, unlike most other pesticides, arsenic occurs naturally and can be found in relatively high levels in the drinking water of some towns in Bangladesh, Japan, Argentina and Taiwan.

Extensive research has shown that arsenic is safe or tolerable to ingest at rates below two µg/kg of body weight per day (World Health Organisation limit), or three µg/kg of body weight per day (Food Standards Australia limit). Indeed, arsenic is the 20th most common element on earth, so the ability for animal life to cope with some level of arsenic is to be expected.

It is important to note that the restrictions applied by the APVMA have occurred as a precaution. The majority of uses for CCA have not been restricted, including industrial, commercial and agricultural uses, farm posts and marine applications.

A link between handling CCA-treated timber (using recommended procedures) and cancer has not been demonstrated, as the potential ingestion rates of arsenic that can be calculated from valid available research are well within tolerable limits. The latest review by ERMA in New Zealand (1) did not find increased health risks from using CCA-treated timber; consequently, no restrictions were applied there. Nevertheless, the APVMA felt that more studies were needed to support the continued use of a potential carcinogen in high human contact applications and that without those studies it should be restricted.

In Australia, treatment levels for CCA are set down by Australian Standards (2) and by state legislation in Queensland and New South Wales. Only dedicated commercial treatment plants have access to CCA solutions. Unlike preservatives such as creosote, liquid CCA is not available to the public at hardware stores.

The approved CCA loading depends on the 'hazard' to which the timber will be exposed, expressed in 'hazard classes' – H1 to H6. Timber used most commonly for domestic purposes is in classes H3 (outdoor above-ground timbers such as decking, fence palings and fascia) and H4 (outdoor in ground contact, for example, posts).

Wood treated according to the standard should carry a stamp or brand, indicating the hazard level to which it was treated. Other numbers in the brand are codes for preservative type and treatment plant number. Since March 2006, labels also state 'Treated with copper chrome arsenate'.

  1. Read D. 2003. Report on Copper Chromium and Arsenic(CCA) Treated Timber  [external link, pdf] Environmental Risk Management Authority (ERMA).
  2. Australian Standard 1604.1-2005. Specification for preservative treatment. Part 1: Sawn and round timber. Standards Australia, Sydney.
  3. Cookson LJ. 2001. Do we need the A in the CCA? 27th Forest Prod. Res. Conf., Clayton, Pp 8-9.
  4. Peoples SA. 1976. The amount and valence of arsenic excreted in the urine of dogs fed CCA-C in their diet. University of California, Davis, CA.
  5. Harrison DL. 1959. Chemically preserved fence posts are harmless to stock. New Zealand J. of Agriculture 98: 293-294.
  6. Ohlson C-G, Andersen A, Evans FG, Karlehagen S, Nilsson K. 1995. Cancer incidence among CCA exposed workers in the wood preserving industry. In: Proceedings of the 3rd International Wood Preservation Symposium - The Challenge - Safety and Environment. International Research Group on Wood Preservation 1995, Document IRG/WP 95-50040-9, 147-149.
  7. Szafraniec T. 1991. CCA exposure in timber workers. J. Occupational Health and Safety: Australia and New Zealand. 7: 401-407.
  8. Levi MP, Huisingh D, Nesbit WB. 1974. Uptake by grape plants of preservatives from pressure-treated posts not detected. Forest Products J. 24: 97-98.
  9. Speir TW, August JA, Feltham CW. 1992. Assessment of the feasibility of using CCA (copper, chromium and arsenic) - treated and boric acid - treated sawdust as soil amendments. Plant and Soil 142: 235-248.
  10. Jorhem L. and K. Nilsson. 1991. Storage of potatoes in impregnated wooden bins. Swedish Wood Preservation Institute, Report No. 165.
  11. Cserjesi AJ. 1976. Permanence of preservatives in treated experimental shake roofs. Forest Products J. 26(12): 34-39.
  12. Wester RC, Hui X, Barbadillo S, Maibach HI, Lowney YW, Schoof RA, Holm SE, Ruby MV. 2004. In Vivo percutaneous absorption of arsenic from water and CCA-treated wood residue. Toxicological Science 79: 287-295.
  13. Lebow S, Foster D, Lebow P. 2004. Rate of CCA leaching from commercially treated decking. Forest Products J. 54: 81-88.
  14. Stilwell DE and Musante CL. 2004. Effect of Coatings on CCA Leaching From Wood in a Soil Environment  [external link, pdf]. In: pre-conference proceedings, Environmental impacts of preservative-treated wood. Florida Center for Solid and Hazardous Waste Management, Gainesville, Florida, pp 113-123.
  15. Better Health. 2005. Copper chrome arsenic (CCA) treated timber [external link]
  16. Cookson LJ. 2005. Arsenic content of soil and wood chip fines in three kindergartens [external link, pdf] Ensis Technical Report No. 151, 16 pp.
  17. Kwon E, Zhang H, Wang Z, Jhangri G, La X, Fok N, Gabos S, Li XF, Le X. 2004. Arsenic on the hands of children after playing in playgrounds. Environmental Health Perspectives 112: 1375-1380.
  18. McCarthy DF. 1978. Ethanolamine et al based wood preservative composition. Australian Patent Appl. No. 35221/78.
  19. Greaves H, Adams N, McCarthy DF. 1982. Studies of preservative treatments for hardwoods in ground contact. 1. Penetration of cell walls by formulations containing copper. Holzforschung 36: 225-231.