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Date Permissions Signed


Date of Award

Winter 2021

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Studies

Degree Name

Master of Arts (MA)


Environmental Studies

First Advisor

Hollenhorstm, Steven J.

Second Advisor

Sofield, Ruth M.

Third Advisor

Van Alstyne, Kathryn Lyn, 1962-

Fourth Advisor

Gaydos, Joseph K.


To increase our seafood safety knowledge with respect to seaweed, this study compares contaminant concentrations in three species of edible seaweeds (Fucus distichus, F. spiralis, and Nereocystis luetkeana) harvested from 43 locations within the Salish Sea from June to September 2015. Fucus spp. were analyzed for 162 chemicals: 17 metals, 94 persistent organic pollutants (POPs) and 51 polycyclic aromatic hydrocarbons (PAHs). Nereocystis luetkeana was analyzed for metal content. Two health-based screening levels were calculated, one on the U.S. Environmental Protection Agency (USEPA) Reference Dose (RfD) and the other on the USEPA Cancer Slope Factor (CSF) when these data were available. Concentrations of Cd, Pb, total PCBs and the PAH benzo(a)pyrene (BaP) at each site were compared to the screening levels (SLs). Concentration of Pb, Cd and Hg were also compared to the French regulations in 2014, for these metals in seaweeds. Generally, contaminants in Salish Sea seaweeds were below detection levels. Concentrations of total PCBs were all below the RfD SL but concentrations in F. distichus at ten of 43 sites and F. spiralis at one of three sites had concentrations above the cancer-based SL. Concentrations of all PAHs at all sites were below the RfD, but BaP concentrations of F. distichus at one of 43 sites and F. spiralis at one of three sites had concentrations above the cancer-based SL. Both sites were in Victoria Harbour, Canada. Screening levels could not be calculated for Pb because no RfDs and CSFs exist. Concentrations in F. distichus at three sites in Victoria Harbour were above the Frenchlegal limit (5 mg/kgdw) for edible seaweeds. Levels of Cd were lower than RfD-based SLs, however, all samples were higher than French legal limit (0.5 mg/kgdw). Total arsenic (tAs) was detected at all sites and ranged from (16-99 mg/kgdw). Concentrations of contaminants in serving sized portions of seaweed samples were compared to concentrations in portions of common foods and within the same general ranges for levels of PCBs, BaP, tAs, Pb, Hg, and Cd contaminants. An important note is that we have reanalyzed the data since the writing of this thesis, although, overall, the results and conclusions have not changed, I would direct you toward that publication for citations of my work (Hahn et al., 2021, in prep.).




Seaweed, Salish Sea, POPs, metals, Fucus, Nereocystis luetkeana


Western Washington University

OCLC Number


Subject – LCSH

Marine algae; Marine algae as food--Salish Sea (B.C. and Wash.); Food contamination; Nereocystis luetkeana--Salish Sea (B.C and Wash.); Fucus--Salish Sea (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and Wash.)




masters theses




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