Potential Effects of Contaminants on Fraser River Sockeye Salmon

Pulp and paper mills, saw mills, and other wood processing facilities are likely torepresent the principal anthropogenic sources <strong>of</strong> these contaminants in the FraserRiver Basin.6.1.4 Pathways for Exposure <strong>of</strong> Fraser River Sockeye Salmon toEndocrine-Disrupting ChemicalsSockeye salmon utilizing habitats in the Fraser River Basin can be exposed to endocrinedisrupting compounds through several pathways. First, direct contact with surface wateris likely to represent an important exposure route for the endocrine disrupting compoundsthat tend to partition into water. Fish have been shown to accumulate nonylphenols,chlorinated phenols, and 17-ethinylestradiol through direct exposure to surface water(Asplund et al. 1999; Larsson et al. 1999; Lye et al. 1999). Certain pesticides (e.g.,organophosphates) and low molecular weight PAHs have octanol-water partitioncoefficients (log Kows) <strong>of</strong> < 4.0 and, hence, can partition into water. Therefore, surfacewater represents a relevant exposure route to these chemicals for sockeye salmon.Many <strong>of</strong> the endocrine disrupting compounds identified in the study area (see Section6.1.2) have log Kows that exceed four and, hence, are considered to be hydrophobic. As aresult, endocrine disrupting compounds such as PCBs, PCDDs/PCDFs, PBDEs, highmolecular weight PAHs, organochlorine pesticides, phthalate esters, and organometalliccompounds tend to partition into particulate matter upon release into aquatic ecosystems.Sockeye salmon can be exposed to these classes <strong>of</strong> endocrine disrupting compoundsduring incubation (i.e., if contaminated sediments are present in incubation substrates orcontaminated groundwater is discharged through such habitats). In addition, sockeyesalmon can be exposed to these substances when particulate matter is released inassociation with effluent discharges from an upland source (e.g., municipal or industrialwastewater) or when contaminated sediments are resuspended in the water column.Exposure to contaminated suspended sediments is most likely to occur during smoltoutmigration and/or upstream migration <strong>of</strong> adult sockeye salmon (i.e., direct releases <strong>of</strong>endocrine disrupting compounds to nursery lakes were not identified in this investigation).Hydrophobic endocrine disrupting compounds also tend to be lipophillic and, hence, tendto accumulate in the tissues <strong>of</strong> aquatic organisms. There is a substantial body <strong>of</strong> literaturedemonstrating that PCBs, PCDDs/PCDFs, PBDEs, organochloride pesticides, andmercury bioaccumulate and/or biomagnify in aquatic food webs. While sockeye salmoncould be exposed to such endocrine disrupting compounds during rearing in nursery lakes,it is more likely that such exposures would occur in rearing habitats in the Lower Fraser82