Dietary exposure of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane to juvenile brown trout (Salmo trutta): bioaccumulation parameters and effects on circulating plasma sex hormones
Notice bibliographique
Résumé
1,2-Dibromo-4-(1,2 dibromoethyl)cyclohexane or tetrabromoethylcyclohexane (TBECH) is an additive bromine based flame retardant used primarily in expandable polystyrene beads that are used mainly to produce thermal insulation for housing. Secondary uses include extrusion into polystyrene foam, adhesive in fabric and vinyl lamination, electrical cable coatings and construction materials. The technical formulation contains two diastereoisomers, α- and β-, which are present in equimolar amounts. Under elevated temperatures two other isomers, γ- and δ-, can be formed. The recent detection of TBECH in the environment and suggestions that all four isomers are androgenic prompted me to examine the bioaccumulation and biochemical effects of one of the isomers, β-, in a controlled laboratory environment. I purposely chose to examine this isomer as it has been detected in biota. Juvenile brown trout (Salmo trutta) were exposed to three different amounts of the β-isomer via their to three different amounts of the β-isomer via their food for 56 days (uptake phase). This was followed by a depuration phase in which all fish were exposed to unfortified food for 77 days. A fourth group of fish were exposed to unfortified food for the duration of the experiment. On days 0, 7, 14, 35, 49, 56, 63, 77, 91, 105, and 133 eight fish from each treatment group were sacrificed and liver, plasma, thyroid and gonad gland were collected and whole-fish (carcass minus tissues above) were collected. Residues of β-isomer were analyzed in the whole-fish and in liver extracts by gas chromatography mass spectrometry in the electron ionization while estradiol (E2), 11-ketotestosterone (11-KT) and testosterone (T) were extracted from plasma and analysed by liquid chromatography tandem mass spectrometry. The bioaccumulation of β-isomer was similar in fish from all treatment groups with steady-state occurring before the end of the uptake phase. Depuration of the β-isomer from fish obeyed first order kinetics and there were no statistically significant differences in the depuration half life (t1/2) among the treatment groups: 22.5 ± 10.4 (low), 13.5 ± 5.9 (med) and 13.8 ± 2.2 (high) days. Steady-state biomagnification factors were much smaller than 1 for fish in all treatment groups. I was unable to detect debrominated metabolites in liver or whole-fish extracts and I also found no evidence of isomerization of the β-isomer to other isoforms in vivo. While there were some differences in E2, T and 11-KT levels in plasma of fish from the treated groups relative to plasma in fish from the control group there were no clear, consistent, discerning trends.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».