Is Bone Mineral Composition Disrupted by Organochlorines in East Greenland Polar Bears (Ursus maritimus)?

• Published in: Environmental health perspectives Vol. 112; no. 17; pp. 1711 - 1716
• Main Authors: Sonne, Christian, Dietz, Rune, Born, Erik W., Riget, Frank F., Kirkegaard, Maja, Hyldstrup, Lars, Letcher, Robert J., Derek C. G. Muir
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01-12-2004; National Institute of Environmental Health Sciences; National Institute of Environmental Health Science
• Subjects: Age; Air pollution; Animals; Bone Density; Bones; Environmental Exposure; Environmental pollution; Female; Femur - chemistry; Greenland; Halogenated diphenyl ethers; Hydrocarbons, Chlorinated - poisoning; In Vitro Techniques; Male; Minerals; Polar bears; Polychlorinated biphenyls; Seals; Skull; Skull - chemistry; Ursidae - physiology; Ursus maritimus; Greenland; Greenland, Oestgroenland
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.7293

We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane (DDT) and its metabolites, chlordanes (CHLs), dieldrin, hexacyclohexanes, hexachlorobenzene] and polybrominated diphenyl ether (PBDE) compounds. To ensure that the BMD value in skull represented the mineral status of the skeletal system in general, we compared BMD values in femur and three lumbar vertebrae with skull in a subsample. We detected highly significant correlations between BMD in skull and femur (r = 0.99; p < 0.001; n = 13) and skull and vertebrae (r = 0.97; p < 0.001; n = 8). BMD in skulls sampled in the supposed pre-organochlorine/PBDE period (1892-1932) was significantly higher than that in skulls sampled in the supposed pollution period (1966-2002) for subadult females, subadult males, and adult males (all, p < 0.05) but not adult females (p = 0.94). We found a negative correlation between organochlorines and skull BMD for the sum of PCBs (ΣPCB; p < 0.04) and ΣCHL (p < 0.03) in subadults and for dieldrin (p < 0.002) and ΣDDT (p < 0.02) in adult males; indications for ΣPBDE in subadults were also found (p = 0.06). In conclusion, the strong correlative relationships suggest that disruption of the bone mineral composition in East Greenland polar bears may have been caused by organochlorine exposure.