The wood protection industry has traditionally relied on only a few first-generation preservatives that have a broad range of activity, are low in cost and exhibit longterm efficacy. The main U.S. preservatives were creosote, oilborne pentachlorophenol and the waterborne arsenicals, principally chromated copper arsenate (CCA). These three systems are still the major preservatives for industrial applications in North America. However, about 70% of the total treated-wood market is residential applications, and wood preservation for residential applications has recently undergone rapid and dramatic changes. Specifically, CCA accounted for over 95% of this market in 2003, but is no longer labeled (permitted) for most residential applications.