Publications by authors named "R J Letcher"

The 2024 Zurich perfluorinated compounds (PFCs) summit reiterated the urgent need for non-selective analytical approaches for PFC detection. 19F NMR holds great potential, however, sensitivity limitations lead to long analysis times and/or the possibility of not detecting low concentration species. Steady State Free Precession (SSFP) NMR collects the signal in a steady state regime, allowing 100's of acquisitions in the timespan of a single traditional NMR scan.

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Metabolomics measures low molecular weight endogenous metabolites and changes linked to contaminant exposure in biota. However, few studies have explored the relationship between metabolomics and contaminants in Arctic wildlife. We analyzed 239 endogenous metabolites and ∼150 persistent organic pollutants (POPs), including total mercury (THg), in the liver of polar bears and their ringed seal prey harvested from low Canadian Arctic (western Hudson Bay; WHB) and high Arctic (HA) locations during 2015-2016.

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As a novel organophosphate ester (NOPE), tris(2,4-di-butylphenyl) phosphate (TDtBPP) has attracted significant attention due to its unexpectedly high detection in natural environments. However, the ecological toxic effects of environmentally relevant concentrations of TDtBPP in organisms remain entirely unknown. In this study, 1 month old zebrafish were exposed to 0, 50, 500, or 5000 ng/L TDtBPP for 150 days, and the reproductive toxicity in male fish was evaluated.

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Article Synopsis
  • Research found significant differences in persistent organic pollutants (POPs) between polar bears and toothed whales in the Arctic, potentially linked to biological susceptibility and feeding patterns.
  • Analyzed samples from 2012 to 2021, killer whales had the highest concentrations of several POPs, while polar bears had lower amounts, especially of organochlorine pesticides.
  • The study highlighted that dietary habits largely influenced PCB concentrations, while biological factors played a larger role in explaining variations in organochlorine levels, indicating complex interactions affecting pollutant accumulation in these species.
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Methoxylated polybrominated diphenoxybenzenes (MeO-PB-DPBs) are little known contaminants except in North American Great Lakes herring gull tissues and egg samples. MeO-PB-DPBs in gulls originate not via aquatic bioaccumulation pathways but instead likely via transformation of the tetradecabromo-1,4-diphenoxybenzene (TDB-DPB) flame retardant (FR). TDB-DPB was formerly produced as SAYTEX-120 in North America and is still produced in Asia.

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