Scientists seek environmentally friendly wood preservative

provided by Mississippi State University

ithin two years, US homeowners will lose their first line of defense against the forces that can destroy decks, fences and other wooden outdoor structures. The Environmental Protection Agency recently announced the phaseout of chromated copper arsenate – CCA – a wood preservative used to treat lumber for protection against termites, fungi and other wood-destroying organisms.

    Currently, more than 95 percent of all treated lumber used in homes, decks and for other residential purposes is treated with CCA, according to Tor Schultz, a wood chemist in the Forest Products Laboratory at Mississippi State University's Forest and Wildlife Research Center.

    “The total cost to US homeowners caused by termites and decay fungi is estimated at about $5 billion per year, so it's important to use treated lumber to protect houses and other structures built of wood,” he said.

    Schultz and other MSU scientists are moving to fill the gap left by the elimination of currently available wood preservatives. “Industry has developed second generation copper/organic wood preservatives, but their use will likely be relatively short term because of the environmental risks associated with copper and issues involved with disposal of wood treated with any metal,” Schultz said.

    Anticipating the eventuality of a CCA ban, Forest Products Lab scientists began work in 1988 on new types of preservative mixtures. Termed “totally organic biocides,” these preservatives will be easier to dispose of because they are environmentally benign.

    While Mississippi State already has received three patents based on organic biocide research, university scientists are working to make the products even more effective and economical.

    “Organic biocide mixtures are costly to make,” Schultz said. “To address this, we have developed formulations that increase the efficiency of the mixture and lower the cost by using inexpensive additives, some of which are so safe they also are used as food additives.”

    Testing of the new wood-protecting formulations began about five years ago, but still has several years to go before the products will be ready for public use.

    “We are conducting both ground-contact and above-ground testing of the products and we need at least 10 years of outdoor results,” Schultz added. “The long testing periods are necessary because treated wood is expected to last for many years in structures like fences and decks.”

    The research could be a major step in developing environmentally friendly and relatively low-cost wood preservatives, which are important to both the forest products industry and homeowners.