Alterations in thyroid hormone status in Greenland sledge dogs exposed to whale blubber contaminated with organohalogen compounds

• Published in: Ecotoxicology and environmental safety 2011, Vol.74 (1), p.157-163
• Main Authors: Kirkegaard, Maja, Sonne, Christian, Dietz, Rune, Letcher, Robert J., Jensen, Asger L., Stige Hansen, Signe, Munro Jenssen, Bjørn, Grandjean, Philippe
• Format: Article
• Language: English
• Subjects: adverse effects; Age; Animal Feed; Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; bitches; blubber; Canis familiaris; carnivores; Cetacea; Contamination; Control equipment; dieldrin; Dieldrin - metabolism; Dieldrin - toxicity; diet; Dogs; Ecotoxicology, biological effects of pollution; Endocrine disruption; Endocrine Disruptors - metabolism; Endocrine Disruptors - toxicity; Environmental Exposure - analysis; Exposure; exposure duration; Female; Food Contamination; Fundamental and applied biological sciences. Psychology; General aspects; Greenland; Hormones; Hydrocarbons, Halogenated - metabolism; Hydrocarbons, Halogenated - toxicity; lipids; Male; Mammalia; Marine; mothers; Organohalogen compounds; Organohalogen contaminants; PCB; polychlorinated biphenyls; Polychlorinated Biphenyls - metabolism; Polychlorinated Biphenyls - toxicity; pups; sisters; Sledge dog; swine; Thyroid; thyroid function; thyroid gland; Thyroid Gland - drug effects; Thyroid Gland - metabolism; thyroid hormones; Thyroid Hormones - metabolism; Thyroxine; Thyroxine - metabolism; Time Factors; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Whales; Whales - metabolism
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2010.08.040

As a model of high trophic level carnivores, sledge dogs were fed from 2 to 18 months of age with minke whale blubber containing organohalogen compounds (OHC) corresponding to 128 μg PCB/day. Controls were fed uncontaminated porcine fat. Thyroid hormone levels were assessed in 7 exposed and 7 control sister bitches (sampled at age 6–18 months) and 4 exposed and 4 control pups, fed the same diet as their mothers (sampled age 3–12 months). Lower free and total T3 and T4 were seen in exposed vs. control bitches beyond 10 months of age, and total T3 was lower through 3–12 months of age in exposed pups. A negative correlation with thyroid gland weight was significant for ΣDDT, as was a positive association with total T3 for dieldrin. This study therefore supports observational data that OHCs may adversely affect thyroid functions, and it suggests that OHC exposure duration of 10 months or more may be required for current OHC contamination levels to result in detectable adverse effects on thyroid hormone dynamics.