Species-Specific Time Trends and Enantiomer Fractions of Hexabromocyclododecane (HBCD) in Biota from East Greenland

Time trends of hexabromocyclododecane (HBCD) isomers were studied for glaucous gull and ringed seal from East Greenland. The ringed seal results extended a previous time trend (1986–2008) to 2010. α-HBCD was the only isomer consistently above quantification limits. For glaucous gull liver, annual median values of α-HBCD (1994–2010) ranged from 22 to 120 ng/g lipid weight (lw) with no significant trend, while HBCD in ringed seal blubber from the same area showed a significant increase from 3.9 to 11 ng/g lw (1986–2010). Reasons for this difference are unknown, but might include different feeding habits and species-specific metabolisation processes. Concentrations of several organochlorine (OC) compounds were determined for glaucous gull and ringed seal samples collected from the same area in 2004. HBCD concentrations in glaucous gull liver appeared relatively low when compared to OC concentrations in the same tissue and to both HBCD and OCs in ringed seal blubber from the same area. Enantiomer fractions (EF) deviated significantly from racemic for all annual mean EFs in glaucous gull suggesting metabolisation processes toward an enrichment of (−)­α-HBCD. For ringed seal, this enrichment was less pronounced and only significant for two of the ten years. For neither species, significant changes in EF were found over time

Median and range of DMSO controls from PHA-L-stimulated PBMCs (n = 6 cultures in duplicates).

<p>Median and range of DMSO controls from PHA-L-stimulated PBMCs (n = 6 cultures in duplicates).</p

Mean of LDH-fluorescence from DE-71 exposed and LPS-stimulated PBMCs.

<p>DE-71 was added in six different concentrations to each culture and medium, and DMSO in medium served as negative controls in duplicate, n = 2 cultures in triplicates. LDH: lactate dehydrogenase, LPS: lipopolysaccharide, DMSO: dimethyl sulfoxid, RFU: relative fluorescence unit.</p

PBDE measurements in stock solution, culture media and cells, mean of double determinations.

<p>PBDE measurements in stock solution, culture media and cells, mean of double determinations.</p

Influence of DE-71 on cytokine responses of PBMCs.

<p>Mean + SD of secretion of TNF-α, IFN-γ, IL-17A, and IL-17F from DE-71 exposed and PHA-L-stimulated PBMCs are shown as ratios to the respective DMSO controls. The red dotted line indicates the level of the DMSO controls (ratio = 1). * = p<0.05 compared to DMSO control, # = p<0.05 compared to 0.01 μg/mL DE-71, + = p<0.05 compared to 0.1 μg/mL DE-71, ¤ = p<0.05 compared to 1 μg/mL DE-71. PBMC: peripheral mononuclear cells, PHA-L: phytohemagglutinin-L, TNF-α: tumor necrosis factor-α, IFN-γ: interferon-γ, IL-17A: interleukin-17a, IL-17F: interleukin-17F DMSO = dimethyl sulfoxide, SD = standard deviation.</p

Mean of LDH-fluorescence from DE-71 exposed and PHA-L-stimulated PBMCs.

<p>DE-71 was added in six different concentrations to each culture, medium and DMSO in medium served as negative controls in duplicate, n = 2 cultures in triplicates. LDH: lactate dehydrogenase, PHA-L: phytohemagglutinin-L, DMSO: dimethyl sulfoxid, RFU: relative fluorescence unit.</p

Median and range of DMSO controls from LPS-stimulated PBMCs (n = 6 cultures in duplicates).

<p>Median and range of DMSO controls from LPS-stimulated PBMCs (n = 6 cultures in duplicates).</p

Tested combinations of deposition efficiencies and field metabolic factors.

<p>a) Only few combinations of proportionality constants: <i>ω_A</i> ( = <i>A_A</i>×<i>f_A</i>) and <i>ω_Y</i>(<i> = A_Y</i>×<i>f_Y</i>) produced predictions not significantly different from actual data: in older bears (blue), yearlings (yellow) or both groups (green). All tested combinations are coloured grey. b) Combinations of <i>ω_A</i> and <i>ω_Y</i> that produced predictions not significantly different from actual data in both studied groups exhibited a negative relationship.</p

Field Metabolic Rate and PCB Adipose Tissue Deposition Efficiency in East Greenland Polar Bears Derived from Contaminant Monitoring Data

<div><p>Climate change will increasingly affect the natural habitat and diet of polar bears (<i>Ursus maritimus</i>). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2′,4,4′,55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.</p></div

Medians of CB153 concentration of bear sub groups.

<p>Comparison between median observed CB153 concentrations in East Greenland polar bears (solid red lines) and CB153 concentration simulated using the best-fitting parameter combinations (black) or randomly selected parameter combinations (blue). Quartiles are shown as bars for model predictions and as dashed red lines for East Greenland bears.</p