What kind of chemicals are in pressure treated lumber?

Friday, May 21, 2010 by Dick Gauthier

ProWood Micro CA pressure treated woodThere are several different types of pressure treated wood available in retail lumber yards today. A discussion involving all of them would result in an alphabet soup of acronyms for the various types of treatment formulations.

At Universal Forest Products, we treat our ProWood Micro CA pressure treated lumber with a formulation known as Micronized Copper Azole, or MCA. And its makeup is simpler than you may have guessed.

The finished product contains two active ingredients to stop decay and termite attack: copper and a non-metallic “organic” called tebuconazole. “Azoles” are used in several everyday personal care products such as foot creams and fungal ointments. Copper is, of course, a common metal used for drinking water pipes, wiring, and other applications that humans come in contact with every day. These two ingredients are applied in a mixture of water at a solution strength of less than 1% active ingredients (99% or more water). The  EPA has registered this preservative and deemed it appropriate for the protection of wood from rot and termites where used as directed. The result is pressure treated wood that is an eco friendly product and servicable for decades.

Comments for What kind of chemicals are in pressure treated lumber?

Thursday, March 3, 2011 by Sandie Pauly:
Is usingCopprt azole which contains fungicides safe for a raised organic garden bed. I thought the EpPA indicated that you shoulod not use preserved wood under circumstances where the preservative may become a component of food, animal feed, or beehives This is using MCA in the chemical process. Please let me know as we want to build a raised garden bed in an organic garden.
Friday, March 4, 2011 by Dick Gauthier:
Thanks for your questions, Sandie. Using ProWood Micro in raised garden beds is safe. Please read the June 24, 2009 blog post entitled "Use pressure treated lumber for raised garden beds". In the comment section (March 9, 2010) you will see info from Scientific Certification Systems, a third-party certification and standards development company. It has awarded MicroPro® (the chemical formulation used in ProWood Micro) its second Environmentally Preferable certification under SCS’s Environmentally Preferable Product (EPP) program, based on Life-Cycle Assessment. Wood products treated with the MicroPro process result in the release of up to 95% less copper into aquatic and terrestrial environments when compared to standard treated wood products. The very small amount released bonds readily to organic matter in the soil and becomes biologically inactive, thus effectively eliminating eco-toxic impacts.

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