Organohalogen concentrations and a gross and histologic ...

Dioxin-like contaminants
Extraction and analyses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-
TCDD) and non-ortho PCB congener 3,3’,4,4’,5-pentachlorobiphenyl (CB-126)
in polar bear fat was conducted by Axys Analytical Services (Sidney, BC,
Canada) used previously described techniques with only minor modification
(U.S. EPA, 1998, 1999). 2,3,7,8-TCDD and CB-126 were chosen as
model dioxin-like contaminants since the former is the most potent AhR
agonist among all dioxin and furan congeners, and CB-126 is the most potent
AhR agonist among all PCB congeners. Briefly, fat samples were homogenized
with Na 2 SO 4 and spiked with mixture of 13 C-labelled non-ortho
PCBs and 2,3,7,8-TCDD surrogate standards to monitor extraction efficiency
and to quantify these analytes in the samples using an isotope dilution approach.
Samples were extracted in toluene via Soxhlet and concentrated.
Extracts were cleaned-up and PCDD/Fs were isolated through a series of
chromatographic columns (U.S. EPA 1998). Analyses was performed using a
high-resolution mass spectrometer coupled to a high-resolution gas chromatograph
(HRGC-HRMS) equipped with a DB5 capillary chromatography
column (60 m ´ 0.25 mm i.d. ´ 0.1 µm film thickness; J&W Scientific, Folsom,
CA, USA). All analytical procedures were carried out according to protocols
as described by U.S. EPA (1998).
Statistics
The statistical analyses were performed with the SAS statistical software
package (SAS V8 and enterprise guide V1) and a significance level of p=0.05
was used except where stated otherwise. Contaminant data was logtransformed
(base e) prior to the analyses in order to meet the criteria of
normality and homogeneity of the variance. The differences in the prevalence
of periodontitis among periods, sex and agegroups were tested with X 2
tests. The difference in organohalogen loads between the two groups with
and without periodontitis was tested by a one-sample F-test.
Results
Periodontitis
The age distribution over the entire period from 1892 to 2002 is viewed in
Fig. 1 (not the large sampling from 1999 to 2002). In the 272 polar bear skulls
that were examined for macroscopic pathological changes, we found cases of
periodontitis, mandibulare/frontale osseus proliferations, adonti (single
tooth), deplacement of tooth, boneloss posterior to M1 and caries in incisivi,
premolar and molar. In old polar bears (≥15 years of age) the severe cases of
periodontitis were accompanied by loss of alveolar bone tissue and tooth
wear. However, only periodontitis was found in frequencies that allowed for
statistical analyses (Fig. 2).
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