Critical review of the association between environmental manganese and thyroid function, with implications for potential neurodevelopmental effects
Bibliographic record
Abstract
Manganese (Mn) is an essential trace element that, in excess, may initiate adverse health effects. Recent evidence suggested that environmental exposure to Mn may produce thyroid hormone imbalances leading to adverse neurodevelopmental outcomes. The aim of this review was to summarize available evidence regarding Mn exposure and consequent adverse thyroid effects, including potential implications for neurodevelopmental impairment in children. Medline, EMBASE, and Scopus were systematically searched using two concepts: Mn exposure and thyroid function. A total of 31 studies (17 human studies, 14 toxicological studies) fulfilled eligibility criteria. Evidence for effects attributed to Mn on the thyroid from human studies is inconclusive. No apparent studies were identified to directly characterize Mn thyroid-mediated effects on neurodevelopmental outcomes. Although limited evidence from animal studies provides some support for the effects of Mn on thyroid-related hormones, it is unclear whether such hormonal imbalance is a result of a direct or indirect biological mechanism of action. Toxicokinetic data demonstrated that Mn accumulates in thyroid tissue and might interfere with thyroid function. Currently, there are limited data on biological mechanisms of action for the effects of Mn on the thyroid. Although evidence to date is suggestive of Mn thyroid-related activity, the lack of adequate studies precludes a causal interpretation.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.007 | 0.008 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".