Elucidating the Pathways of Poly- and Perfluorinated Acid Formation in Rainbow Trout
Bibliographic record
Abstract
Several studies have shown that fluorotelomer-based compounds can be metabolized to poly- and perfluorinated carboxylates, such as perfluorooctanoate (PFOA). Research has predominately focused on the 8:2 fluorotelomer alcohol (8:2 FTOH), however, the biotransformation pathway is not well understood. Specifically, there is uncertainty regarding the biological fate of the 8:2 fluorotelomer unsaturated carboxylate (FTUCA) and 7:3 fluorotelomer saturated carboxylate (FTCA). The objective of this study was to further elucidate the pathway for 8:2 FTOH biotransformation through dosing rainbow trout with three 8:2 FTOH metabolism intermediates: the 7:3 FTCA (CF(3)(CF(2))(6)CH(2)CH(2)COO(-)), 8:2 FTCA (CF(3)(CF(2))(7)CH(2)COO(-)), and 8:2 FTUCA (CF(3)(CF(2))(6)CF horizontal lineCHCOO(-)). This study represents the first investigation of these three labile intermediate metabolites in an in vivo system. The parent compounds were dosed via the diet and the parent compounds and intermediates were monitored in the blood and liver during the 7-day uptake phase and 10-day elimination phase. Exposure to the 7:3 FTCA did not result in the formation and accumulation of PFOA, but resulted in low levels of the 7:3 FTUCA and perfluoroheptanoate, a novel finding. PFOA was formed in the 8:2 FTCA and 8:2 FTUCA dosing. In addition, the 7:3 FTCA was formed during exposure to both the 8:2 FTCA and 8:2 FTUCA. Elimination half-lives were 5.1 d (95% confidence interval: 3.1-14 d) for 7:3 FTCA, 1.2 d (1.1-1.3 d) for 8:2 FTCA, and 0.39 d (0.31-0.53 d) for 8:2 FTUCA. The observed differences in the elimination half-life may be the result of differences in either the depuration or metabolism rate. Based on the findings of this study, and reported analogous literature pathways, we proposed a "beta-like-oxidation" pathway for PFOA formation proceeding from the 8:2 FTUCA > 7:3 beta-keto acid > 7:2 ketone > PFOA. Alternatively PFOA could be formed directly through the beta-oxidation of the 7:3 beta-keto acid.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.004 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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 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".