Copper chrome arsenate treated timber

Copper chrome arsenate (CCA) is a water-borne solution of up to 25% copper, up to 45% chromium and up to 37% arsenic. This treatment makes the timber highly resistant to pests and fungi but it can also be toxic when handled or burnt, and should never be used for household building or renovation.

copper chrome arsenate treated logs

Copper chrome arsenate treated logs

Copper is a fungicide, arsenic prevents insect attacks and chromium binds the other two elements to the timber. When used as a treatment, CCA makes up about 1% of the timber volume. If the timber is burnt, however, the smoke and ash contain high concentrations of arsenic.

Hazard level of copper chrome arsenate treated timber

H3 to H6.

What does copper chrome arsenate treat?

Moderate to very severe decay, borers and termites, marine wood borers.

Typical uses of copper chrome arsenate treated timber

CCA treated timber can be used outside, in and above the ground, and in fresh or seawater.

CCA treated timber is used for

  • framing
  • landscaping
  • building poles
  • jetty piles
  • fencing

It must not used for residential decking, garden furniture, picnic tables, exterior seating, patios and handrails.

Do not use copper chrome treated timber for household building or renovation

CCA treated timber contains arsenic which can harm people and animals if

  • it is absorbed through skin while working with CCA treated timber
  • excessive amounts of sawdust are inhaled or swallowed when cutting CCA treatedtimber
  • you are exposed to ash from burning CCA treated timber
  • 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.

For more information see the NSW Department of Health CCA treated timber fact sheet

Regulation and copper chrome arsenate treated timber

In 2004, the Australian Pesticides and Veterinary Chemical Authority (APVMA) advised that CCA must not to be used in Australia for high-contact structures such as

  • playground equipment
  • garden furniture
  • picnic tables
  • exterior seating
  • patios
  • domestic decking
  • handrails

From July 2012, CCA was declared a restricted chemical product. For more information, see

Existing structures containing copper chrome arsenate

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. Some items do not need to be individually labelled, but the packaging must be marked. These include

  • fence palings
  • battens
  • droppers
  • pieces less than 15 mm thick or with a cross section below 1500 mm2

Safe handling

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.

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