Are Ministry of Environment holding times for nitrate and nitrite tests in drinking water justified?
Bibliographic record
Abstract
Background: Exposure to nitrate and nitrite in high concentration is associated with various health issues in humans such as methemoglobinemia, gastric and bladder cancers. Surface and ground water is vulnerable to nitrate and nitrite contamination which can have a significant impact to communities that use the water for consumption. Methods: Ion chromatography analysis of nitrate and nitrite degradation over time in well water from Abbotsford-Sumas Aquifer was performed in an analytical chemistry study. Nitrate and nitrite test strips marketed for testing drinking water were also used and results were compared to ion chromatography results. Results: Test strips used were unable to detect the level of nitrate/nitrite in the well water sample drawn from the Abbotsford-Sumas aquifer. Ion chromatography, IC, methods were able to detect measurable amounts of nitrates which resulted from concentrations of 1.17 mg/L NO3 as N to 1.13 mg/L NO3 as N from day 0 to 31 of the sampling date. The concentration decreased 0.04 mg/L NO3 as N over 31 days. Nitrites tested by IC were below the detection limit. Conclusion: In regards to nitrates, the MOE holding times are justified in that the concentrations were statistically different (p = 0.0001) from day 0 to day 31 from the sampling date indicating a change of concentration of the chemical due to time. However, the difference was not of a magnitude that may impact public health practices/policies. Test strips comparisons with EPA IC methods were non-conclusive since test strips were unable to detect measurable amounts of nitrate/nitrites. Future studies of nitrate concentrations with respect to chemical and biological components in water may lead to a greater understanding of its change in the environment and thus its association with other potential health hazards.
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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 | 0.028 | 0.058 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.007 | 0.004 |
| Insufficient payload (model declined to judge) | 0.017 | 0.004 |
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".