Levels and Risk Assessment of Polychlorinated Biphenyls (PCBS) in Soils from Informal E-Waste Recycling Sites in Cameroun
Bibliographic record
Abstract
This study assessed the levels and human health risk of polychlorinated biphenyls (PCBs) in soils of e-waste recycling sites in Douala, Cameroun. Surface soil samples from these sites were collected and analyzed by Gas Chromatography- Electron Capture Detector to quantify the levels of 30 PCBs (including 10 dioxin-like PCBs). The investigated 30 PCBs were detected in all the soil samples. The mean and standard deviation of the total PCBs in Makea, Ngodi and New Bell recycling sites were 32.1±4.48, 31.9±0.10 and 72.8±13.5 ng/g, respectively. Between 26-46% of the Ʃ30 PCB concentrations were comprised of the dioxin-like PCB congeners. The toxic equivalent (TEQ) values of 10 dioxin-like PCBs were lower than the Canadian soil quality guidelines of dioxin (4 pg TEQ g−1). Human health risk through ingestion, dermal contact, and inhalation was lower than the values of cancer risk (10−6) indicating low adverse effects of PCBs in the recycling sites.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".