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Assessing the Release of Copper from Nanocopper-treated and Conventional Copper-treated Lumber into Marine Waters II: Forms and Bioavailability
Citation:
Parks, A., M. Cantwell, D. Katz, M. Cashman, T. Luxton, J. Clar, M. Perron, L. Portis, K. Ho, AND R. Burgess. Assessing the Release of Copper from Nanocopper-treated and Conventional Copper-treated Lumber into Marine Waters II: Forms and Bioavailability. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 37(7):1969-1979, (2018).
Impact/Purpose:
In recent years, copper nanomaterials have been selected to be used as wood preservatives in lumber applied in exterior and aquatic construction. For example, if a porch is being built, it is now likely the wood preservative that the lumber is treated with to defend against insects and molds damage is copper nanomaterial. Unfortunately, there is limited information about the behavior of nanocopper if it released into the environment from treated lumber. For this research, we examined the form of copper released from nanocopper pressure-treated lumber under estuarine and marine conditions. Three different methods (i.e., filtration; ion selective electrochemistry; toxicity testing) were used to determine the form of copper released. Overall, the form of copper released from the nanocopper pressure-treated lumber was found to be the ionic form rather than some form of nanocopper. From an environmental management perspective, this is relatively good news. There is a great deal of information available on the fate and effects of ionic copper in the aquatic environment which means measures can be taken to reduce the adverse effects of any ionic copper released from nanocopper pressure-treated lumber.
Description:
One application of nanocopper is as a wood‐preserving pesticide in pressure‐treated lumber. Recent research has shown that pressure‐treated lumber amended with micronized copper azole (MCA), which contains nanosized copper, releases copper under estuarine and marine conditions. The form of copper released (i.e., ionic, nanocopper [1–100 nm in size]) is not fully understood but will affect the bioavailability and toxicity of the metal. In the present study, multiple lines of evidence, including size fractionation, ion‐selective electrode electrochemistry, comparative toxicity, and copper speciation were used to determine the form of copper released from lumber blocks and sawdust. The results of all lines of evidence supported the hypothesis that ionic copper was released from MCA lumber and sawdust, with little evidence that nanocopper was released. For example, copper concentrations in size fractionations of lumber block aqueous leachates including unfiltered, 0.1 μm, and 3 kDa were not significantly different, suggesting that the form of copper released was in the size range operationally defined as dissolved. These results correlated with the ion‐selective electrode data which detects only ionic copper. In addition, comparative toxicity testing resulted in a narrow range of median lethal concentrations (221–257 μg/L) for MCA lumber blocks and CuSO4. We conclude that ionic copper was released from the nanocopper pressure‐treated lumber under estuarine and marine conditions. Environ Toxicol Chem 2018;37:1969–1979. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
