Thyroid gland lesions in organohalogen contaminated East Greenland polar bears ( <i>Ursus maritimus</i> )
Bibliographic record
Abstract
Thyroid gland histology was examined in 20 organohalogen contaminant (OHC)-exposed East Greenland polar bears (Ursus maritimus). OHC concentrations measured in subcutaneous adipose tissue were between 3556 and 28,670 ng g−1 lw for polychlorinated biphenyls (ΣPCB51), 9 and 3403 ng g−1 lw for the sum of organochlorine pesticides (hexachlorocyclohexanes, hexachlorobenzene, chlordanes, dichlorodiphenyltrichloroethanes, and dieldrin), and from 21 to 130 ng g−1 lw for polybrominated diphenyl ethers. Histological examinations revealed that 12 of the bears (10 males aged 3–19 years and two females aged 4–7 years) had normal thyroid tissue while eight bears (40%) of varying ages and genders (three males aged 3–9 years and five females aged 4–25 years) showed clear histological lesions including parafollicular C-cell proliferation, nodular hyperplasia, and interstitial fibrosis. No significant differences were found in prevalence of thyroid gland lesions between males and females. Similarly, no marked difference was found in mean age between individuals with and without lesions. There was no significant difference in OHC mean concentrations between males and females or between individuals with and without lesions. Despite no documented relationship to OHC concentrations in adipose tissue, it is worth noting that the lesions were similar to that of OHC exposed lab and wildlife contaminated mammals. Since the lesions were not associated with age or gender, other environmental factors such as energetic stress and autoimmunity/genetic predisposition also need to be considered. It is therefore possible that OHCs, in combination with other environmental and intrinsic factors described in the literature, may interfere with the hypothalamic–pituitary–thyroid axis (HPT axis) resulting in endocrine perturbations in East Greenland polar bears.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".