A comparative toxicity assessment of materials used in aquatic construction

Abstract

Comparative toxicity testing was done on selected materials that may be utilized in aquatic construction projects. The tests were conducted on the following materials: untreated wood species (Hemlock (Tsuga ssp), Western red cedar (Thuja plicata), Red oak (Quercus rubra), Douglas fir (Pseudotsuga menziesii), Red pine (Pinus resinosa) and Tamarack (Larix ssp)); plastic wood; Ecothermo wood™; hemlock stakes treated with preservatives (chromated copper arsenate (CCA), creosote, alkaline copper quaternary (ACQ), zinc naphthenate, copper naphthenate and Lifetime Wood Treatment™); epoxy coated steel; rolled steel; zinc coated steel and concrete. Those materials were used in acute lethality tests with Rainbow trout, Daphnia magna, Vibrio fischeri and Threespine stickleback. The results indicated the following general ranking of the materials (from the lowest to highest LC50 values); ACQ > creosote > zinc naphthenate > copper naphthenate > CCA (treated at 22.4kg/m3) >concrete > red pine > western red cedar > red oak > zinc coated steel > epoxy coated steel > CCA (6.4kg/m3). Furthermore, the toxicity results indicated that plastic wood, certain untreated wood species (hemlock, tamarack, Douglas fir and Red oak), rolled steel, Ecothermo Wood™ and wood treated with Lifetime Wood Treatment™ were generally non-toxic to the test species.