Persistent organic pollutants such as polychlorinated biphenyls (PCB) are known to disrupt steroidogenesis and subsequent concentrations of circulating endogenous hormones. This is also suspected to occur in Arctic predatory species, such as polar bears (Ursus maritimus) and a study was therefore conducted in Greenland sledge dogs (Canis familiaris) as a sentinel species for adverse effects on steroid homeostasis. The control and exposed groups were composed of four sister-bitches all fed pork fat (Suis suis) and organohalogen contaminated minke whale (Balaenoptera acutorostrata) blubber, respectively, for 321–576 days. In the exposed group, this constituted a mean daily intake of 128 μg ∑PCBs (5 μg/kg/day). At the end of the study, organohalogen contaminant (OHC) were measured in adipose tissue and hormone levels in blood of sledge dogs. The hormones included 11 products of the steroidogenesis, which were ∑Androgen (dehydroepiandrosterone, androstenedione, testosterone, and dehydrotestosterone), ∑Estrogen (estrone, 17α-estradiol and 17β-estradiol), and ∑Progestagen (pregnenolone, progesterone, 17-OH-pregnenolone, and 17-OH-progesterone) concentrations. This allowed us to study the mechanisms underlying possible disruption of blood steroid concentrations. Results showed that exposed bitches had significantly higher concentrations of all OHC compounds. Unexpectedly, ∑Androgen, ∑Estrogen and ∑Progestagen concentrations were also significantly higher in exposed dogs. Data indicated that daily OHC contaminant exposure were concomitant with elevation in concentrations of steroid hormones in blood plasma of exposed sledge dogs. Based on these unexpected results, data suggest that more investigations should be focused on steroid endocrine disruption and potential health effects in Arctic top predators including domesticated dogs.
Environmental Toxicology and Chemistry, 2014, Vol 96, Issue 2, p. 273-286