Silver-based wood coatings

In mid-February, legislation was introduced in the U.S. House of Representatives that would provide funding for a study on the effectiveness of silver-based biocides as an alternative treatment to preserve wood.

The initiative, known as the Wood Preservation Safety Act of 2003, directs the Forest Products Laboratory in Madison, Wis., to conduct a study on the effectiveness of silver-based biocides as a wood preservation treatment.

Last year, the Environmental Protection Agency (EPA) and representatives from the chemical and home-improvement industries negotiated an agreement to phase out, by 2004, the use of arsenic-based wood preservatives in pressure-treated lumber. This will affect virtually all residential uses of wood treated with chromated copper arsenate (CCA), including wood used in playgrounds, decks, picnic tables, landscaping timbers, residential fencing, patios and walkways.

In the U.S., corporations such as Home Depot and Lowe’s have announced they will stop selling lumber treated with arsenic-based preservatives.

The Consumer Products Safety Commission also is entering the long-running debate about the health risks of playground equipment made from pressure-treated wood. Earlier this month, the agency released a staff study of 12 playgrounds in the Washington, D.C., area. It concluded that children who play on equipment made of wood treated with CCAs could face an increased risk of developing lung or bladder cancer.

If silver-based biocides were used as an alternative to harmful arsenic-based preservatives, more than 100 million oz. of silver a year would be consumed. This would represent a significant hike in silver demand.

— The preceding is from a bulletin published by the Washington, D.C.-based Silver Institute.