Photoinduced toxicity of polycyclic aromatic hydrocarbons to<i>Daphnia magna</i>: Ultraviolet-mediated effects and the toxicity of polycyclic aromatic hydrocarbon photoproducts
Bibliographic record
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants known for their photoinduced toxicity. This toxicity may occur through two mechanisms: Photosensitization, and photomodification. Photosensitization generally leads to the production of singlet oxygen, a reactive oxygen species that is highly damaging to biological molecules. Photomodification of PAHs, usually via oxidation, results in the formation of new compounds and can occur under environmentally relevant levels of actinic radiation. The toxicities of 16 intact PAHs to Daphnia magna were assessed under two ultraviolet radiation conditions. The toxicity of intact PAHs generally increased in the presence of full-spectrum simulated solar radiation relative to that in the presence of visible light plus ultraviolet A only. Despite the knowledge of a bipartite mechanism of phototoxicity that includes photosensitization and photomodification, few studies have examined the effects of PAH photoproducts on animals. To expand the existing data, 14 PAH photoproducts (oxy-PAHs) also were assayed, most of which were highly toxic without further photomodification. Two photoproducts of benzo[a]pyrene, 1,6- and 3,6-benzo[a]pyrenequinone, were the most toxic compounds tested, followed closely by benz[a]anthraquinone. Each of these three compounds had a median effective concentration in the low nanomolar range. The data presented highlight the effects of ultraviolet radiation on mediating PAH toxicity and the need to analyze absorption spectra of contaminants in the prediction of photoinduced toxicity. The importance of the role of photomodification also is stressed, because several oxy-PAHs, an unregulated group of contaminants, were highly toxic to D. magna, a key bioindicator species in aquatic ecosystems.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".