Polychlorinated Biphenyl Exposures and Cognition in Older U.S. Adults: NHANES (1999–2002)
Bibliographic record
Abstract
BACKGROUND: Polychlorinated biphenyls (PCBs) are ubiquitously present in humans because of their resistance to degradation and accumulation in fatty tissues. Data on neurotoxic effects in older adults are limited. OBJECTIVE: We examined the cross-sectional association between serum PCB concentrations and cognitive function in older adults from the general U.S. population. METHODS: We analyzed data from 708 respondents, 60-84 years of age, participating in the National Health and Nutrition Examination Survey (1999-2002). We used the summed concentrations of 12 lipid-standardized PCB congeners as the measure of exposure and assessed cognitive function with the Digit-Symbol Coding test. We adjusted analyses for age, education, race/ethnicity, and poverty/income ratio. RESULTS: The median concentration of lipid-standardized PCBs in serum was 271 ng/g (interquartile range, 193-399 ng/g). We found a significant interaction between dioxin-like PCB concentration and age in association with cognitive score (p=0.04). Among older individuals (70-84 years of age), a 100-ng/g increase in serum concentrations of dioxin-like PCBs was associated with a significantly lower cognitive score (-2.7 points; 95% CI: -5.1, -0.2; p=0.04); however, in younger individuals (60-69 years of age), there was a nonsignificant positive association (2.9 points; 95% CI: -1.8, 7.7; p=0.32). Among the older participants, the negative association was more pronounced in women than in men. CONCLUSION: Our findings support the hypothesis that PCB exposure has adverse cognitive effects even at levels generally considered to pose low or no risk, perhaps affecting mainly those of advanced age.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.015 | 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; both teacher heads agree on what is shown here.
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".