A Review of the Evidence for Endocrine Disruption in Canadian Aquatic Ecosystems

Endocrine disrupting substances in the environment and the potential affects they have on wildlife species has recently received increased public attention. This paper provides background information on research that has addressed the endocrine disruption issue in the Canadian aquatic environment as well as information on studies that are presently being conducted within the country to address this issue. Two of the three studies from across the world often cited as presenting sufficient evidence for connecting contaminants and endocrine disruption in fish populations are Canadian — Lake Ontario lake trout and TCDD and related compounds, and white sucker exposed to bleached kraft pulp mill effluent. Several other Canadian examples exist, including altered stress responses in yellow perch exposed to heavy metals, altered smoltification in Atlantic salmon exposed to 4-nonylphenol and imposex in dogwelks exposed to tributyltin. While other Canadian studies suggest alterations in reproductive function in fish, direct links to contaminants have not been made. Other studies have identified endocrine active compounds in the receiving environments but have yet to link these to alterations in endocrine function in resident fish populations. The strength of Canada’s research programs lies in the breadth and depth of their field related research. It is this world-recognized expertise and strength that Canada can contribute to the international effort to address the endocrine disruptor issue.