Improving Understanding of Endocrine-Active Compounds in Pulp and Paper Mill Condensates Using a Mummichog (<em>Fundulus heteroclitus</em>) Bioassay
Bibliographic record
Abstract
Since the late 1990s an investigation of cause (IOC) study at Irving Pulp and Paper Ltd (IPP), a bleached kraft mill in Saint John, NB, Canada, has successfully identified an in-mill waste stream (5th effect evaporator condensates) as containing endocrine disrupting substances (EDSs). These EDSs affect levels of reproductive steroids in a native estuarine fish, the mummichog (Fundulus heteroclitus). To confirm the minimal concentration at which whole condensates impact reproductive endpoints, adult mummichog were exposed to 2% and 4% (v/v) whole condensates for 14 days. Plasma testosterone was significantly depressed in males in the 4% (v/v) treatment, confirming previous work done with IPP condensates. Also, significant induction of hepatic cytochrome P450 genes 1 and 3 were found in female fish exposed to both condensate concentrations. To chemically isolate suspect EDSs, a solid phase extraction protocol was developed by collaborating researchers. The protocol generates four chemically-distinct fractions, along with residual condensates. Fractionation was completed using 4% (v/v) whole condensates and the resultant fractions, and 4% (v/v) whole condensates, were exposed to adult mummichog in the reproductive endocrine bioassay. There was no significant response in fish exposed to 4% (v/v) whole condensates, making interpretation of specific fraction treatments difficult. While fish were in different reproductive periods in the two bioassays, which may account for some of the differences between the experiments, a more compelling explanation is the variability in the chemical make-up of the condensates. Chemical fingerprinting of both condensate batches by collaborating researchers found a higher androgenic potency in the fractionation condensates. Mummichog were then exposed to model androgens methyltestosterone (100 and 1000 ng/L; MT) and dihydrotestosterone (10 and 100 μg/L; DHT) to determine if androgenic responses paralleled condensate responses. Plasma testosterone was significantly depressed by 10 μg/L DHT in males. Females had significant depression of plasma estradiol when exposed to both DHT concentrations and 1000 ng/L MT. Female mummichog had lower thresholds of effects than males and were more responsive to androgen exposure. Comparison of effects seen in fish exposed to pulp mill condensates and those exposed to model androgens indicate androgens in the condensates may not be the source of reproductive endocrine effects in the condensate-exposed mummichog.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".