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Nunavimmiut (Inuit of Nunavik, Northern Quebec, Canada) exhibit a high selenium (Se) status because of their frequent consumption of marine mammal foods. Indirect evidence from our previous studies had suggested that selenoneine – a novel selenocompound – may be accumulating in the blood of Nunavimmiut. We used a liquid-chromatography/inductively coupled tandem mass spectrometry (LC-ICP-MS/MS) method to measure concentrations of selenoneine and its methylated metabolite Se-methylselenoneine in archived red blood cells (RBC) obtained from 210 Nunavimmiut living in communities along the Hudson Strait, where marine mammal hunting and consumption are most frequent in Nunavik. This method was adapted to quantify selenoneine and its methylated metabolite in beluga mattaaq, an Inuit delicacy consisting of the skin with the underlying layer of fat and the major dietary source of Se for Nunavimmiut. Total selenium concentration was also measured in RBC and beluga mattaaq samples by isotope dilution ICP-MS/MS. The median selenoneine concentration in RBC was 413 μg Se/L (range = 3.20–3230 μg Se/L), representing 54% (median) of total Se content (range = 1.6–91%). Quantification of selenoneine in five beluga mattaaq samples (skin layer) from Nunavik revealed a median concentration of 1.8 μg Se/g wet wt (range = 1.2–7.4 μg Se/g), constituting 54% (median) of the total Se content (range = 44–74%). Se-methylselenoneine was also detected in Inuit RBC but not in beluga mattaaq, suggesting that selenoneine undergoes methylation in humans. Selenoneine may protect Nunavimmiut from methylmecury toxicity by increasing its demethylation in RBC and in turn decreasing its distribution to target organs. Image 1 • LC-ICP-MS/MS was used to quantify selenoneine and Se-methylselenoneine in RBCs. • Selenoneine represented 54% of total Se content in Inuit RBCs. • Selenoneine was also the major Se species in beluga mattaaq – an Inuit delicacy. • Selenoneine may protect Inuit against methylmercury toxicity. [ABSTRACT FROM AUTHOR]

Abstract: In recent times, there has been an increased concern over the appearance of human estrogens in marine ecosystem and their effects on the marine habitat. Discharge of raw sewage has been identified as one of the most important sources of human estrogens in the marine environment. Therefore, we have developed a gas chromatography–(ion-trap) mass spectrometry/mass spectrometry method for the analysis of natural estrogens estrone (E1), and 17β-estradiol (E2) and synthetic estrogens 17α-ethynylestradiol (EE2) and diethylstilbestrol (DES) in sewage effluents, seawater and mussels. Recovery of target analytes from mussels (n =3) was above 60% with RSD ranging from 8% to 13%. For aqueous samples (n =3) recoveries were above 80% with RSD ranging from 3% to 7%. Method detection limits for the target analytes ranged from 0.1ngg−1 to 1.0ng/g for mussel sample analysis and from 0.5ngL−1 to 1.2ngL−1 for water sample analysis. The usefulness of the method was demonstrated by analyzing environmental samples from St. John’s and Halifax, Canada, where raw sewage is directly discharged into the harbors. Estrone and 17 β-estradiol were found at 1.5ngL−1 and 1.8ngL−1 in seawater samples collected from St. John’s harbor, while trace amounts of estrone was measured in some mussels collected from Halifax harbor. [Copyright &y& Elsevier]