Copper Chrome Arsenic (CCA), wood preservative is used for timber treatment. CCA contain Chromium, Copper and Arsenic. Wood Preservative - CCA is used in pressure treated wood to protect wood from dry rot, fungi, molds, termites, and other pests that can threaten the integrity of wood products. The chromium acts as a chemical fixing agent and has little or no preserving properties. Chromium helps the other chemicals to fix in the timber, binding them through chemical complexes to the wood's cellulose and lignin. The copper acts primarily to protect the wood against decay fungi and bacteria, while the arsenic is the main insecticidal component of Copper Chrome Arsenic, CCA.