Occurrence of the Tire-Derived Toxicant 6PPD-Quinone in Road Dust from Unpaved Roads in a Cold-Region Urban Area
Bibliographic record
Abstract
In 2021, mortalities of coho salmon were linked to 6PPD-quinone (6PPD-Q), a transformation product formed from an antioxidant in rubber tires. Since then, research concerning 6PPD-Q contamination pathways has focused on paved roads. However, over half of the road network in Canada consists of unpaved roads, which remain unstudied for 6PPD-Q contamination. In this paper, we hypothesize that (1) unpaved road networks can provide a pathway for 6PPD-Q to enter the environment and (2) 6PPD-Q concentrations in unpaved road dust are influenced by location, speed limit, collection date, and total organic carbon (TOC) content of the roads. To investigate this, we collected gravel from the surface of unpaved roads in and around Saskatoon, Saskatchewan, Canada. Chemical extractions of road dust allowed for the detection and quantification of 6PPD-Q within each sample. Concentrations of 6PPD-Q ranged between 0.207 and 1.47 ng/g of dw (median: 0.511 ng/g of dw). When normalized to TOC content, concentrations varied between 9.83 and 342 ng/g of TOC (median: 145 ng/g of TOC). No factor other than the speed limit showed a positive linear relationship with 6PPD-Q concentrations. The results of this study are an initial glimpse into the role unpaved roads play in adding 6PPD-Q into the environment.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.005 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".