Copper chrome arsenate
Copper chrome arsenate (CCA) is a water-borne solution of up to 25% copper, up to 45% chrome and up to 37% arsenic.
CCA treated logs
Not all green treated timber is CCA. Green tinged LOSP timber treated to H3.
Copper is a fungicide, arsenic prevents insect attacks and chromium binds the other two elements to the timber. When used as a preservative CCA makes up about 1% of the timber volume. If treated timber is burnt, however, the smoke and ash contains high concentrations of arsenic.
Hazard level: H3 to H6 (not residential decking)
See the Hazard level and chemical treatment types chart for more information.
Moderate to very severe decay, borers and termites, marine wood borers and decay
Framing, landscaping timbers, building poles, jetty piles, fencing
Outside, in-ground and above ground, contact with or in fresh water, marine waters.
Not used for residential decking, garden furniture, picnic tables, exterior seating, patios and handrails.
CCA treated timber contains arsenic.
Arsenic can cause harm:
- if it is absorbed through skin while working with CCA timber
- if excessive amounts of sawdust are inhaled or swallowed when cutting CCA timber
- if exposed to ash from burnt CCA timber
- if you have frequent contact with soil that has been mulched with CCA treated timber woodchips or sawdust
Symptoms include pins and needles, nausea, vomiting and diarrhoea.
If you think you have been exposed, seek medical advice.
In 2004, the Australian Pesticides and Veterinary Chemical Authority (APVMA) advised that CCA is not to be used in Australia for playground equipment or other high-contact structures such as garden furniture, picnic tables, exterior seating, patios, domestic decking and handrails.
The APVMA also advised that existing structures made from CCA treated timber do not need to be removed. If you are worried about children having contact with the arsenic in CCA, paint the surfaces with an oil-based polyurethane product or paint.
CCA vegetable planters can be lined with plastic.
CCA treated timber in Australia must be marked with the words ‘Treated with copper chrome arsenate’ either in the form of individual labels fixed to the ends of wood, or as brands along its length. Individual items of CCA treated timber such as fence palings, battens, droppers, pieces less than 15mm thick or with a cross section below 1500mm2 do not need to be individually labelled, but the packaging must be marked.
It is commonly believed that all green-tinged timber is CCA, but other treated timbers which do not contain arsenic may also appear green.
Because labels and brands can be removed or fade with time, identification can be difficult. If you are unsure what a treated timber structure is made from, you should play it safe and handle and dispose of it as if it is treated with CCA.
More about safe handling.
Page last updated: 12 May 2016