Pressure Treated Lumber and the Next Generation of Wood Preservatives
June 21, 2004
In the past, wood has been preserved by pressure-treatment with a pesticide containing inorganic arsenic (referred to as Chromated Copper Arsenate or CCA) to protect it from insect attack and decay.
Inorganic arsenic penetrates deeply into and remains in the pressure-treated wood for a long time. However, some chemicals may migrate from treated wood into the surrounding soil over time and may also be dislodged from the wood surface upon contact with skin.
Therefore, the following precautions should be taken both when handling the treated wood and in determining where to use or dispose of the treated wood. If you do chose to use arsenical pressure-treated wood, please use the following precautions.
· Do not use treated wood under circumstances where the preservative may become a component of food or animal feed. Examples of such sites would be use of mulch from recycled arsenic-treated wood, cutting boards, counter tops, animal bedding, and structures or containers for storing animal feed or human food.
· Only treated wood that is visibly clean and free of surface residue should be used for patios, decks and walkways.
· Treated wood should not be used where it may come into direct or indirect contact with drinking water.
· If you already have landscaping or other projects built with treated wood and wish to take precautions to prevent leaching into your flowerbeds, etc., you can mix 3 tablespoons of copper spray (available from garden centres) into 1 pint of raw linseed oil and brush or spray the mixture onto the treated wood.
· Treated wood should not be burned because toxic chemicals may be produced as part of the smoke and ashes.
· When sawing, sanding, and machining treated wood, wear a dust mask. Whenever possible, these operations should be performed outdoors to avoid indoor accumulations or airborne sawdust from treated wood.
· When power sawing and machining, wear goggles to protect eyes from flying particles.
· Wear gloves when working with the wood. After working with the wood, and before eating or drinking, wash exposed areas thoroughly.
The next generation in wood preservation is Alkaline Copper Quat (ACQ). This preservative does not require the use of fixation chambers. The North American chemical suppliers to the pressure treating manufacturers voluntarily changed from Chromated Copper Arsenate (CCA) to ACQ by the end of December 2003.
The fundamental safety of CCA treated wood has not changed, but perceptions in the marketplace have. The preserved wood industry stands by the safety of all wood products treated with CCA which has been used for nearly 70 years. Manufacturers have made a decision to be responsive to customer interest in new preservatives that provide the same benefits of CCA treated wood.
The time for the change (to ACQ treated products) is right now because the industry has developed this new generation of preservatives and can provide a more acceptable alternative.
Remember the key benefits of treated wood: Preservatives make and keep wood products sturdy, stable and safe. They prevent decay, termite damage and extend the life of the products from just a few years to decades.
For more information about the next generation of wood preservation – Alkaline Copper Quat, deck materials, preserved lumber, retaining walls, and fences, please visit Greentree Wood Products’ website at www.greentreewood.com