Multi-component assessment of worker exposures in a copper refinery : Part 1. Environmental monitoring
Bibliographic record
Abstract
The exposure characterisation described in this paper for 135 copper refinery workers (45 females, 90 males) focuses on the concentrations of copper, nickel and other trace elements in the inhalable aerosol fractions, as well as in the water-soluble and water-insoluble subfractions. Some information is also provided on the thoracic and respirable aerosol fractions. Further, results are presented for volatile hydrides of arsenic and selenium released in the copper purification steps of the electrorefining process. For the pyrometallurgical operations, a comparison of the geometric means for the inhalable aerosol fraction indicated that water-soluble copper levels were on average 19-fold higher compared to nickel (p < 0.001) and a significant association was evident between them (r = 0.87, p < 0.001); for the insoluble subfraction, the copper : nickel ratio was 12.5 (p < 0.001) and the inter-element correlation had r = 0.98 and p < 0.001. Although for the electrorefinery workers the relative inhalable concentrations of copper and nickel were not significantly different (p > 0.05), the corresponding inter-element associations were: slope of 7.7, r= 0.54, p < or =0.001 for the water-soluble subfraction and slope of 1.3, r = 0.71 and p < or =0.001 for the water-insoluble subfraction. On average, a good proportion of the inhalable copper and nickel were found in the thoracic (40%) and respirable (20%) aerosol fractions. Cobalt air concentrations were generally low with geometric means and 95% confidence intervals of 3.1 (2.4-4.2)microg m(-3) (pyrometallurgical workers) and 0.3 (0.4-0.5) microg m(-3)(electrorefinery workers). Similarly, the maximum concentrations of cadmium and lead were low, respectively 4 and 25 microg m(-3). Of the hydrides, tellurium and antimony could not be detected, but for the arsenic (arsine) and selenium hydrides measurable exposure occurred for almost all electrorefinery workers, although the levels were generally low at 0.2 microg m(-3).
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".