title: Skull pathology in East Greenland and Svalbard polar bears (Ursus maritimus) during 1892 to 2002 in relation to organochlorine pollution.
abstract: East Greenland and Svalbard polar bears (Ursus maritimus) are heavily polluted with long-range transported organochlorines such as PCBs (polychlorinated biphenyls). To investigate the negative health impacts, a time-trend study of skull pathology was conducted on 269 East Greenland and 241 Svalbard polar bears. The skulls were sampled during 1892-2002 and 1964-1992, respectively. Seven different pathological changes were found: adonti, displacement of teeth, caries, osseous proliferations, exostosis, tooth wear and periodontitis. Only tooth wear and periodontitis was in a prevalence that allowed statistical treatment. The most severe cases of tooth wear and periodontitis were accompanied by a substantial loss of alveolar bone structure. The prevalence of tooth wear and periodontitis increased significantly with age (p<0.001) with incisor wear being more severe than in canines, premolars and molars (p<0.001). No sex difference was found for tooth wear (p=0.22) while a significant difference between sexes was found for periodontitis (p=0.01) with males having higher prevalence than females (odds ratio of 2.5 for males:females). In East Greenland, the prevalence of tooth wear was significantly higher in polar bears collected in the pre pollution period (<1960) than in bears sampled during polluted periods (1960-1980 and 1981-2002) (p<0.001). Regarding periodontitis, the prevalence was not significantly different between pre-pollution and pollution periods (p=0.309). Polar bears from Svalbard had significantly higher prevalence of tooth wear (p<0.001) and periodontitis (p=0.02) than polar bears from East Greenland. The tooth wear and periodontitis odds ratios for Svalbard:East Greenland were 135 and 2.6, respectively. Hence, we found a clear age/sex link and geographical difference but no evidence for an association between skull pathology and exposure to organochlorines in East Greenland and Svalbard polar bears.
authors.affiliation: National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, DK-4000 Roskilde, Denmark. csh@dmu.dk
authors.forename: Christian
authors.initials: C
authors.lastname: Sonne
authors.forename: Frank F
authors.initials: FF
authors.lastname: Rigét
authors.forename: Rune
authors.initials: R
authors.lastname: Dietz
authors.forename: Oystein
authors.initials: O
authors.lastname: Wiig
authors.forename: Maja
authors.initials: M
authors.lastname: Kirkegaard
authors.forename: Erik W
authors.initials: EW
authors.lastname: Born
mesh_terms: D000820:Animal Diseases / Q000453:epidemiology; D000818:Animals; D004784:Environmental Monitoring / Q000379:methods; D004787:Environmental Pollution; D062665:Epidemiological Monitoring; D005260:Female; D006116:Greenland / Q000453:epidemiology; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D008297:Male; D010518:Periodontitis / Q000453:epidemiology / Q000662:veterinary; D012886:Skull / Q000473:pathology*; D013538:Svalbard / Q000453:epidemiology; D014070:Tooth / Q000473:pathology; D001503:Ursidae
chemical_list: D006843:Hydrocarbons, Chlorinated