Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Although urban areas occupy only 2% of the Pacific Northwest land base, the impacts of
urbanization on aquatic ecosystems are severe and long lasting (Spence, Lomnicky et al.
1996). O’Neill et al. (2006) found that Chinook salmon returning to Puget Sound had
significantly higher concentrations of PCBs and PBDEs compared to other Pacific coast
salmon populations. Furthermore, Chinook salmon that resided in Puget Sound in the
winter rather than migrate to the Pacific Ocean (residents) had the highest concentrations
of persistent organic pollutants (POPs), followed by Puget Sound fish populations
believed to be more ocean-reared. Fall Chinook salmon from Puget Sound have a more
localized marine distribution in Puget Sound and the Georgia Basin than other
populations of Chinook salmon from the west coast of North America. This ESU is more
contaminated with PCBs (2 to 6 times) and PBDEs (5 to 17 times). O’Neill et al. (2006)
concluded that regional body burdens of contaminants in Pacific salmon, and Chinook
salmon in particular, could contribute to the higher levels of contaminants in federallylisted
endangered southern resident killer whales.
Endocrine disrupting compounds (EDCs) are chemicals that mimic natural hormones,
inhibit the action of hormones and/or alter normal regulatory functions of the immune,
nervous and endocrine systems and can be discharged with treated effluent (King County
2002d). Endocrine disruption has been attributed to DDT and other organochlorine
pesticides, dioxins, PAHs, alkylphenolic compounds, phthalate plasticizers, naturally
occurring compounds, synthetic hormones and metals. Natural mammalian hormones
such as 17β-estradiol, are also classified as endocrine disruptors. Both natural and
synthetic mammalian hormones are excreted through the urine and are known to be
present in wastewater discharges.
Jobling et al. (1995) reported that ten chemicals known to occur in sewage effluent
interacted with the fish estrogen receptor by reducing binding of 17β-estradiol to its
receptor, stimulating transcriptional activity of the estrogen receptor or inhibiting
transcription activity. Binding of the ten chemicals with the fish endocrine receptor
indicates that the chemicals could be endocrine disruptors and forms the basis of concern
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