Preview Article: The Future of CCA

In March this year new regulations came into effect with regard to the use of CCA (Copper Chrome Arsenate) on timber products…

Background
Three years ago, the United States and Canadian wood preservation industries in conjunction with the US Environmental Protection Agency and the Canadian Pest Management Regulatory Agency (PMRA) agreed on a voluntary transition away from CCA treated timber products for non-industrial usage. The transition, which took effect from January, 2004, followed examination of the safety of CCA-treated products over a number of years. Studies detected arsenic on the surface of treated product and in soil below CCA-treated structures, causing some concern in consumers. However, the North American regulatory agencies advised that products already in use posed no significant threat to health. CCA continues to be used in North America in commercial and industrial applications such as poles, piling and retaining structures.

What is CCA?
CCA (Copper Chrome Arsenate) is a well-established water-borne preservative used to protect timber from all major biodeteriogens, including decay fungi, wood boring insects, termites, and marine borers. The CCA concept was invented by an Indian engineer in 1933 and is used in countries around the world where wood preservation plays an important part in building. Overall, Australians rank number three in the world on the basis of per capita consumption of treated timber, behind New Zealand and the USA.
AHJPreview01Aug06
When the elements copper (Cu), chromium (Cr), and arsenic (As) are introduced into the timber in combination with water, the formulation is designed so they react with each other and with the wood structure to become fixed as insoluble compounds. The fixation mechanism is dependent upon temperature, relative humidity, time, pH and the actual formulation of CCA used. There should be no unfixed chemicals in or on the surface of treated timber and, therefore, very little leaching of elements into the environment from the timber when it enters service. Today, most CCA-treated timber is produced by processes that accelerate the fixation mechanism, leaving the timber surfaces clean and relatively dry.

Treatment plants use CCA in accordance with Australian Standards and the Australian and New Zealand Environment and Conservation Council guidelines. Most of the health and safety concerns about using CCA focus on the arsenic and, to a lesser extent, the chromium, as both are potentially harmful to human health, either as poisonous substances or as carcinogenic chemicals. However, according to the Timber Preservers Association of Australia, the hazards to health of these elements in CCA-treated timber are low. The industry has for several years offered alternative chemicals to CCA which contain no arsenic or chromium, that are registered and approved for use and incorporated in Australian Standards. They include ACQ and Copper Azole. CCA continues to be a widely used preservative treatment because it’s most familiar to specifiers and users, is cost competitive, and has a proven track record.

The Australian Pesticides & Veterinary Medicines Authority (APVMA) regulates the use of wood preservatives up to the point of sale of the treated timber. The APVMA recently reviewed CCA as a timber treatment, reinforcing its status as a safe, durable, and inexpensive way to preserve wood for most outdoor purposes. The APVMA, however, has imposed restrictions on certain products with which the public, notably children, come into frequent contact. From March 12, 2006, CCA should not be used for treating timber intended for use as garden furniture, picnic tables, exterior seating, children’s play equipment, patio and other domestic decking boards and handrails.

AHJPreview02Aug06
All other timber may continue to be treated with CCA, but these products will be required to be marked with the words ‘Treated with Copper Chrome Arsenate’. The APVMA is introducing the changes to CCA use through label variations. The label instructions are legally binding on the chemical suppliers and the chemical users (treaters) in Australia. The new label changes also require compliance with a number of treatment plant operational aspects, as set down in AS/NZS 2843. CCA-treated timber producers can obtain details of these specific requirements from the CCA chemical suppliers.

Marking Guide
The timber industry has developed a guide to marking all CCA-treated timber produced after March 12, 2006. The new label instructions specify that CCA-treated timber should be marked with both the normal branding, in accordance with the AS1604 series of Standards (plant number, chemical number and hazard class), as well as the statement ‘Treated With Copper Chrome Arsenate’.

Marking Requirements:
For all hazard classes of timber treated in accordance with the AS 1604 series of standards, each separate piece of treated timber is required to be “legibly and sufficiently permanently marked” with the following information:

 

  • Treatment plant number
  • Preservative code number
  • Hazard class number.In addition, all timber that is treated with CCA should be legibly marked with the words ‘Treated with copper chrome arsenate’.Exemptions from Marking
    In accordance with AS1604 series, the following treated products are not required to be individually marked but shall be pack-marked:
  • Battens, fence palings and droppers
  • Timber 1500 mm2 and less in cross section
  • Timber less than 15 mm nominal sawn thickness dimension.Imported CCA-Treated Timber
    AHJPreview03Aug06
    The APVMA does not have jurisdiction over non-Australian producers and therefore has no authority to impose requirements on imported, treated timber products.Controlling the use of CCA-treated imported timber is the timber industry’s own responsibility and it has agreed with the APVMA to self-regulate such timber products. The industry intends to impose a self-regulated prohibition on CCA-treated timbers intended for use in garden furniture, picnic tables, exterior seating, children’s play equipment, handrails, patio and domestic decking boards.Summary
    After March 12, 2006, CCA may not be used to treat timber products produced, either in Australia or overseas, and intended for use as garden furniture, picnic tables, exterior seating, children’s play equipment, patio and domestic decking boards, and handrails. CCA may be used to treat timber products produced either in Australia or overseas, that are intended for all other uses, as long as they are marked with the words ‘Treated with Copper Chrome Arsenate’. Garden furniture, picnic tables, exterior seating, children’s play equipment, patio and domestic decking and handrails treated with CCA prior to March 12, 2006, may be sold until the supply is exhausted.For more information visit: www.tpaa.com.au

    To read the rest of this article, see the Timber feature of the August Australian Hardware Journal.