The objective of this study was to compare leaching rates of various wood preservatives from treated wood and the tests used to gather this information. The preservatives compared included CCA and the copper-based alternatives, MCQ, ACQ, and MCA. The tests compared included AWPA E11, SPLP, TCLP, and environmental leaching tests. Among all of the tests evaluated, environmental tests most closely simulate natural environments. Compared to environmental tests submersion based tests such as AWPA E11 resulted in artificially high leaching rates. The leaching rates obtained by the synthetic precipitation leaching procedure (SPLP) were the closest to those predicted by the environmental tests. In general, MCQ, ACQ and MCA – treated wood leach more copper than CCA primarily because they have higher retention levels of copper for the same use applications. Despite this, advantage of the copper-based alternatives is that they do not contain or leach arsenic or chromium.

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