Bibliographic record
Abstract
Before a site is considered contaminated, concentrations of chemicals, particularly natural elements, should be compared to data from local or regional surveys of background soil quality in uncontaminated areas, if data are available. On-site levels would be considered to be consistent with background where the maximum measured concentration of a COPC is less than or equal to a representative statistic for background concentration. If it is found that concentrations of Contaminants of Potential Concern (COPCs) at the site are representative of background levels, then the site may not be contaminated despite the fact that generic environmental quality guidelines are exceeded. In a human health risk assessment, if concentrations of a contaminant are within the range of local or regional background conditions, the contaminant should be excluded from further consideration as a COPC. The concept of background concentrations of chemicals varies among jurisdictions. Potential background levels can be derived from data taken from control sites located close to, but outside the influence of the contaminated site, or may be based on more regional values. Whichever concept is employed, there is a need for a standardized approach to assessing the availability and appropriateness of data on background levels, or evaluating the need for sampling background concentrations at a reference site. CCME Soil Quality Guidelines - Human Health Many contaminants, particularly metals, are naturally occurring, and natural levels can exceed CCME soil quality guidelines and other generic guidelines without representing anthropogenic contamination. When setting national guidelines, the CCME derives guideline values by determining the tolerable or essentially negligible concentration of a contaminant above the background (natural) level (CCME, 2006). The CCME also recognizes that natural levels in soil vary spatially, and recommends that local soil quality objectives be established that incorporate local or regional background concentrations if they are significantly different from the background value used in the derivation of the national generic guideline for a particular contaminant (CCME, 1996). In principle, for threshold contaminants, the total exposure from direct soil pathways should not generally exceed typical background soil exposures by more than 20% of the residual tolerable daily intake (RTDI), although >20% may be allotted under certain circumstances. If the chemical is identified as a non-threshold substance by Health Canada, then a guideline will be developed
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.028 | 0.031 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.008 | 0.004 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.005 | 0.002 |
| Open science | 0.005 | 0.005 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.066 | 0.015 |
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".