Disruptive effects of persistent organohalogen contaminants on thyroid function in white whales (Delphinapterus leucas) from Svalbard

Concentrations of vitamin A, E, thyroid and testosterone hormones in blood plasma and tissues from emaciated adult male Arctic foxes (Vulpes lagopus) dietary exposed to persistent organic pollutants (POPs)

“…The apparent small effects on circulating concentrations of thyroid hormones in the present POPs exposed adult male foxes were in contrast to reports of lowered levels of FT3, TT3, FT4 and TT4 in adult female Greenland dogs that also were exposed to dietary consumption of POPs (Kirkegaard et al, 2011), and the associations between POPs and thyroid hormones reported in several other free-living Arctic mammals (Braathen et al, 2004;Gabrielsen et al, 2015;Knott et al, 2011;Villanger et al, 2011aVillanger et al, , 2011b. In some of these studies, thyroid hormone levels in females appear to be more affected by POPs.…”

“…polar bears, seal spp. and beluga whales (Delphinapterus leucas) Gabrielsen et al, 2015;Letcher et al, 2010;Simon et al, 2013;Sonne, 2010;Villanger et al, 2011aVillanger et al, , 2011b. POP exposure is also known to induce oxidative stress through the production of peroxides and free radicals that may damage components of the cell, including proteins, lipids, and DNA (Palace et al, 1996b;Twaroski et al, 2001aTwaroski et al, , 2001b.…”

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

“…As T3 is the active hormone and FT3 represents the biologically available fraction, this may be of concern for the polar bear health. Accordingly, previous studies on mammals reported negative relationships between plasma concentrations of FT3 and PCBs in Svalbard female polar bears with COYs (Braathen et al, 2004), grey seal pups (Halichoerus grypus; Sørmo et al, 2005) and beluga whales (Delphinapterus leucas; Villanger et al, 2011b). Moreover, a study on pregnant women reported low levels of FT3 and TT3 in women with high blood concentrations of PFUnDA and PFDA, respectively, compared to women with low blood concentrations of these compounds (Berg et al, 2015).…”

Thyroid hormones and deiodinase activities in plasma and tissues from East Greenland polar bears (Ursus maritimus) during winter season

“…free and protein-bound) and free T4 and T3 in plasma (T4 P , fT4 P , T3 P , fT3 P , respectively) were conducted at the Norwegian University of Science and Technology, Trondheim, Norway, using commercially available solid-phase 125 I radioimmune assay (RIA) kits (Coat-A-Count Free T3; Coat-A-Count Free T4; Coat-A-Count Total T3; Coat-A-Count Total T4, Siemens Medical Solutions, CA, USA) without modifications. Although developed for human use, commercial kits have been validated to be applicable to polar bear (Braathen et al 2004;Bytingsvik 2012) as well as other marine mammals' plasma Villanger et al 2011b) by running a parallelism assay of diluted samples with the standards curve. This is due to the fact that THs are highly conserved among vertebrate species (Zoeller et al 2007).…”