A Preliminary Comparative Toxicity Assessment of Materials Used in Aquatic Construction

Environment Canada undertook a preliminary comparative toxicity assessment of selected materials that may be utilized in construction projects located in the aquatic environment. That project involved introducing Fahlstrom sized test stakes (3.9x0.54x26.4 cm) to both fresh and salt water for toxicity testing. Rainbow Trout, Daphnia magna and Microtox testing was conducted in freshwater and Threespine Stickleback were utilized for the salt water testing. Test protocols followed the Environment Canada Acute Lethality Tests 19901992. This preliminary assessment utilized untreated Hemlock, Plastic Wood, Wood treated with Life Time Wood Treatment, Bois Ecotherm, and stakes treated with CCA, Creosote or ACQ. Prior to introduction of the test organisms, the test materials were submerged in tanks of various sizes, using glass as a counterweight for 24 hours. The toxicity results suggest that Plastic Wood, Untreated Hemlock, Ecotherm Wood and wood treated with Lifetime Wood Treatment are generally non-toxic to the test species in the freshwater or the marine environment. The other three treatments (i.e. CCA, Creosote, ACQ) were toxic in varying degrees, and the testing indicated that Creosote and CCA are less toxic than ACQ treated wood. This report has been prepared to release the data in a timely fashion. The testing program is on-going, and the report will be released in a revised version as results of tests on additional treated and untreated wood samples and other construction materials are obtained.