The facts about CCA-treated timber

CCA safety overview

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CCA-treated timber is safe to use, so long as all safety precautions are followed. Evidence of health problems associated with this use has not been proven. Because arsenic at higher levels is a carcinogen, and alternative wood preservatives are available, restrictions in some domestic applications have been applied as a precaution.

Problems can arise if warnings are not heeded and timber is misused or burnt. The difficulties of recycling CCA-treated timber and disposing of waste are significant drawbacks for the preservative and the subject of current scientific research.

Alternatives to CCA

Alternatives to CCA are available but are not yet widely used because wood treated with them is generally more expensive than CCA-treated timber. They combine copper and organic preservatives and are more environmentally friendly than CCA as they do not contain chromium or arsenic.

One alternative, alkaline copper quat (ACQ), is currently registered for use in all hazard classes except H6 (marine use). Tanalith E (copper azole) covers hazard classes H1 to H4 and H5 in softwoods (for example, decking and posts). Both have been extensively tested and generally perform as well as CCA.

Remember to use hot-dip galvanised or stainless steel nails or screws when fixing these treated timbers.

Other preservatives suitable for out-of-ground-contact uses include a number of light organic solvent preservative (LOSP) formulations.

If greater use were made of such alternatives, their price could be expected to fall. A concern with restricting CCA is that treated timber prices will rise and consumers will turn to more environmentally harmful materials such as aluminium, steel and concrete. These are not renewable, and greenhouse gases are generated in large quantities during their manufacture.

What is CSIRO doing?

CSIRO has a comprehensive development and testing program in wood protection technology. Indeed, CSIRO invented copper ethanolamine nonanoate (CEN) in the late 1970s (19) (20). CEN is a precursor to some of the current alternatives (copper ethanolamine quat = ACQ).

CSIRO helps industry and preservative suppliers by testing new wood preservatives and formulations according to established criteria for obtaining APVMA approval and recognition under Australian Standards. In addition, CSIRO is investigating accelerated test methodology so that potential alternatives can be evaluated more rapidly.

Learn more about CSIRO’s Wood research.

  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.