Occurrence of Cyclic Volatile Methylsiloxanes in Surface Waters
Bibliographic record
Abstract
Cyclic volatile methylsiloxanes (cVMS) are commonly present in cosmetic and personal care products, healthcare products and many industrial applications. Because cVMS are persistent, they end up in the wastewater and go untreated through the wastewater treatment units, which lead to contamination of the surface waters through effluent discharge. The three most common cVMS are: octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). It was determined that D4 is very toxic to some aquatic organisms at very low concentrations of 6.3 ug/L, which meets the toxicity criterion of the European Commission. D4 was classified as Category 3 for reproductive toxicity by the European Commission. It was determined by Dow Corning Corporation that D5 showed a potential carcinogenic effect in a 2-year chronic toxicity and carcinogenicity study. cVMS are often measured by gas chromatography/mass spectrometry for precise measurement. In two UK rivers D5 was detected at <0.01-0.03 ug/L. A study from Canada reported <0.01-0.02 ug/L of D4, <0.03-1.45 ug/L of D5 and <0.02-0.15 ug/L of D6 in a river studied. Because these cVMSs were detected at considerable levels, they are under consideration by the UK Environment Agency and Canadian Environmental Assessment Agency for drinking water regulations and are declared as harmful to the environment by Environment Canada and Health Canada. This study focused on refining the available detection methods for cVMSs and to monitor the occurrence of them in local wastewater treatment plants. After refining a headspace chromatography/mass spectrometry method, 0.69 ug/L of D4 and 2.14 ug/L of D5, in the effluent from Drake Wastewater Treatment Facility (WWTF), Fort Collins, CO and 0.97 ug/L of D4 and 2.61 ug/L of D5 in the effluent from Loveland Wastewater Treatment Plant, Loveland, CO were detected. These results indicate that the surface waters receiving the effluents from these two WWTFs are likely to contain considerable amounts of D4 and D5.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.000 |
| 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".