title: Bone-related effects of contaminants in seals may be associated with vitamin D and thyroid hormones.
abstract: The high levels of polychlorinated biphenyls (PCBs) and DDT in gray seal (Halichoerus grypus) and ringed seal (Phoca hispida botnica) in the Baltic Sea have been associated with pathological disruptions, including bone lesions and reproductive failures. The underlying environmental and toxicological mechanisms leading to these pathological changes are not yet fully understood. The present study investigated the relationship between the individual contaminant load and bone- and thyroid-related effects in adult gray seals (n=30) and ringed seals (n=46) in the highly contaminated Baltic Sea and in reference areas (Sable Island, Canada, and Svalbard, Norway). In the gray seals, multivariate and correlation analyses revealed a clear relationship between circulating 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D), calcium, phosphate, and thyroid hormone (TH) levels and hepatic PCB and DDT load, which suggests contaminant-mediated disruption of the bone and thyroid homeostasis. Contaminants may depress 1,25(OH)(2)D levels or lead to hyperthyroidism, which may cause bone resorption. In the ringed seals, associations between circulating 1,25(OH)(2)D, THs, and hepatic contaminants were less prominent. These results suggest that bone lesions observed in the Baltic gray seals may be associated with contaminant-mediated vitamin D and thyroid disruption.
authors.affiliation: Norwegian Polar Institute, Polar Environmental Centre, 9296 Tromsø, Norway. routti@npolar.no
authors.forename: Heli
authors.initials: H
authors.lastname: Routti
authors.forename: Madeleine
authors.initials: M
authors.lastname: Nyman
authors.forename: Bjørn Munro
authors.initials: BM
authors.lastname: Jenssen
authors.forename: Christina
authors.initials: C
authors.lastname: Bäckman
authors.forename: Jaana
authors.initials: J
authors.lastname: Koistinen
authors.forename: Geir Wing
authors.initials: GW
authors.lastname: Gabrielsen
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000187:drug effects*; D008099:Liver / Q000033:anatomy & histology*; D046048:Seals, Earless / Q000378:metabolism*; D013961:Thyroid Gland / Q000187:drug effects*; D013963:Thyroid Hormones / Q000097:blood*; D014807:Vitamin D / Q000032:analysis* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D013963:Thyroid Hormones; D014874:Water Pollutants, Chemical; D014807:Vitamin D