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.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| 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".