Survey for Tributyltin in Water and Sediment in Canada in 1999

A survey of water and sediment from 152 harbours, marinas and shipping channels across Canada was conducted in 1999 to determine the extent of contamination by tributyltin (TBT) prior to the total ban on its antifouling uses being phased in over the period 2003 to 2008, and to assess the effectiveness of the 1989 regulation of antifouling uses of TBT under the Canadian Pest Control Products Act. TBT was found in sediments in this survey much more frequently than in water. The main conclusion was that by 1999 the regulation had been generally effective in reducing TBT contamination in water, but not sediment, in small-craft marinas and harbours. TBT continued to be found in some freshwater and seawater locations frequented by larger vessels, that could have been legally painted at the time with TBT antifouling paints, at concentrations that could cause chronic toxicity to aquatic organisms. TBT was also found in many marine sediments, and some freshwater sediments, at concentrations that could cause chronic toxicity to sensitive benthic organisms. In addition, TBT concentrations in many marine sediments could cause acute toxicity to sensitive benthic organisms. Because of the long persistence of TBT in sediments, it may pose a hazard to benthic organisms in some locations in Canada for many years after the total ban on antifouling uses of TBT.