Environmental lead exposure assessment for children from pre-1970's housing in St. John's, NL
Bibliographic record
Abstract
Environmental media samples from residential properties throughout St. John’s, NL were collected to examine the amount of lead contamination across housing age categories, as previous studies indicated that environmental lead levels on residential properties are above national guidelines, particularly on older properties. Methods: Environmental media samples were collected from properties participating in the study. 194 study households were sampled, representing 249 participants aged 6 months to 6 years. These included soil, indoor dust, indoor tap water, interior and exterior paint chips and garden produce samples. Statistical analyses examined the relationship between housing age category and strong-acid extractable lead levels in media samples, as well as, between media and existing data on children's blood lead levels. A bioaccessibility analysis was also undertaken for soil lead. Results: Significantly higher (p <0.0001) near-total lead concentrations were found for pre-1970 homes compared to reference post-1980 homes for dust, soil, water post-stagnation and paint. Overall the lead content of household floor dust was found to be correlated with concentrations in paint chips and soil, and to be weakly correlated to children’s blood lead levels (p <0.0001, r = 0.13). There was also a weak relationship on correlation analysis for tap water stagnation levels 1,2 and 4 and blood lead levels, as well as for our housing age category of pre-1970. Results of a 1 M HNO3 bioaccessibility method had a strong positively correlation to near-total lead concentrations, and only weakly correlated to other soil properties of CEC content: Mg and K for dripline soil samples. Conclusion: There are elevated levels of lead in indoor dust, soils and tap water of residential properties throughout St. John’s, which may represent an exposure risk to children’s health.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".