(Table 2) Mercury and selenium concentration in the brain stem of wild polar bears (Ursus maritimus), east Greenland, supplement to: Basu, Niladri; Scheuhammer, Anton M; Sonne, Christian; Letcher, Robert J; Born, Erik W; Dietz, Rune (2009): Is dietary mercury of neurotoxicological concern to wild polar bears (Ursus maritimus)? Environmental Toxicology and Chemistry, 28(1), 133-140

• Main Authors: Basu, Niladri, Scheuhammer, Anton M, Sonne, Christian, Letcher, Robert J, Born, Erik W, Dietz, Rune
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2009
• Subjects: Category; Parameter; Sample amount; Mercury; Mercury, standard deviation; Selenium; Selenium, standard deviation; Ratio; Standard deviation; Biological sample; Advanced Mercury Analyser AMA-254, LECO; International Polar Year 2007-2008 IPY; Arctic; Dietz; Greenland; East Greenland; International Polar Year; IPY; Ursus maritimus
• Online Access: https://dx.doi.org/10.1594/pangaea.807159; https://doi.pangaea.de/10.1594/PANGAEA.807159

Polar bears (Ursus maritimus) are exposed to high concentrations of mercury because they are apex predators in the Arctic ecosystem. Although mercury is a potent neurotoxic heavy metal, it is not known whether current exposures are of neurotoxicological concern to polar bears. We tested the hypotheses that polar bears accumulate levels of mercury in their brains that exceed the estimated lowest observable adverse effect level (20 µg/g dry wt) for mammalian wildlife and that such exposures are associated with subtle neurological damage, as determined by measuring neurochemical biomarkers previously shown to be disrupted by mercury in other high-trophic wildlife. Brain stem (medulla oblongata) tissues from 82 polar bears subsistence hunted in East Greenland were studied. Despite surprisingly low levels of mercury in the brain stem region (total mercury = 0.36 ± 0.12 µg/g dry wt), a significant negative correlation was measured between N-methyl-D-aspartate (NMDA) receptor levels and both total mercury (r = -0.34, p < 0.01) and methylmercury (r = -0.89, p < 0.05). No relationships were observed among mercury, selenium, and several other neurochemical biomarkers (dopamine-2, gamma-aminobutyric acid type A, muscarinic cholinergic, and nicotinic cholinergic receptors; cholinesterase and monoamine oxidase enzymes). These data show that East Greenland polar bears do not accumulate high levels of mercury in their brain stems. However, decreased levels of NMDA receptors could be one of the most sensitive indicators of mercury's subclinical and early effects. : Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150