As of January 2004, wood preservers voluntarily removed wood
treated with chromated copper arsenate (CCA) from consumer markets,
citing concerns the arsenic and chromium contained in CCA pose
possible environmental concerns in exposed-to-weather applications.
CCA treatment had been used successfully for preservative-treated
wood since the early 1930s, and those in the roofing industry had
grown accustomed to specifying and using CCA-treated lumber as wood
blocking and wood nailers in roof assemblies.
Wood preservers have introduced a number of preservative
treatment substitutes, including alkaline copper quant type C
(ACQ-C), alkaline copper quant type D carbonate (ACQ-D carbonate),
micronized copper quant (MCQ), copper azole (CBA-A, CA-B),
ammoniacal copper zinc arsenate (ACZA), sodium borate disodium
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