Industrialization and food safety for the Tsleil-Waututh Nation: An analysis of chemical levels in shellfish in Burrard Inlet.

While Indigenous food systems remain critical for community well-being, traditionally harvested foods are a potential source of toxic exposures. The Tsleil-Waututh Nation (TWN) is seeking to restore shellfish harvesting in Burrard Inlet (British Columbia [BC], Canada), where the cumulative effects of industrial activity have nearly eliminated safe harvesting. The Trans Mountain Expansion project would triple the capacity to transport oil through the inlet, threatening TWN's progress to restore shellfish harvesting. To inform ongoing efforts we assessed contamination by heavy metals (arsenic, cadmium, lead, and mercury) and 48 polycyclic aromatic hydrocarbons (PAHs) congeners in different shellfish species (Softshell clams, Varnish clams, and Dungeness crab) in three areas. We compared our results against local screening values (SVs) established by the TWN and BC Ministry of Environment and Climate Change Strategy, as well as provincial and national benchmarks. In total, we analyzed 18 composite samples of Softshell clams and Varnish clams (5 individuals per sample), as well as 17 individual crabs. We found chemical contamination in all species at all sites. PAHs were most frequently detected in Softshell clams, highest in the site closest to the pipeline terminus. Clams presented higher levels of contamination than crabs for PAHs, but not for heavy metals. For Softshell and Varnish clams, all heavy metals across study sites exceeded at least one of the population-specific SVs. Of the 14 PAHs detected, benzo(a)pyrene presented a median concentration in Softshell clams of 3.25 µ/kg, exceeding local SV for subsistence fisher. Our results call for further assessment of human health impacts related to food harvesting within Burrard Inlet and establishing a long-term coordinated program co-led by the TWN to monitor contamination and inform future harvesting programs. The study draws attention to the need to consider locally-relevant toxicity benchmarks, and include potential health impacts of food contamination in appraising development project proposals.

Determination of benzene, toluene, ethylbenzene and xylenes by headspace spectrophotometry with an atomic absorption apparatus.

In this study an atomic absorption spectrophotometer equipped with a selenium hollow-cathode lamp was used for analysis of BTEX (benzene, toluene, ethylbenzene and xylenes) in headspace of aqueous solutions. Initially effective factors on headspace such as volume of solution, stirring time, stirring speed, velocity of carrier gas, temperature, number of strippings, addition of salts and salt concentration were investigated and optimum conditions were selected. By addition of salt in different concentrations, different absorbances were obtained for headspace, therefore, binary mixtures of BTEX were analyzed with simultaneous equations. Obtained results agreed with actual amounts and repeatability was very good (RSD% < 3). Correlation coefficients (r) for calibration curves were about 0.999. This proposed method is comparable with absorbance determination of solution with respect to correlation coefficient, linear dynamic range, limit of detection (LOD) and relative standard deviation (RSD), but this method is less susceptible to interferences and more selective.