VALIDATING URINARY TRICHLOROACETIC ACID AS A BIOMARKER OF EXPOSURE FOR DISINFECTION BYPRODUCTS IN DRINKING WATER-A THIRD HUMAN TRIAL
Notice bibliographique
Résumé
Epidemiologic evidence of disinfection by-products (DBPs) causing adverse human health effects needs improved assessment of individual drinking water exposure to DBPs. Development of a feasible biomarker offers an approach to this need. Trichloroacetic acid (TCAA) in urine was confirmed to have sufficiently long retention (urinary excretion half lives from two to six days) in two previous human exposure pilot trials (ten participants in Adelaide, Australia and five participants in Edmonton, Canada) to make urinary TCAA a promising candidate as a biomarker. The current pilot study is to verify our protocol for performing a larger scale human exposure trial (∼50 participants) to ultimately validate urinary TCAA as a biomarker of non-volatile DBP exposure via drinking water. In December 2002, we recruited sixteen healthy women of reproductive age to participate in this study. Following an initial telephone interview, ten eligible volunteers were selected to obtain demographic data, patterns of food, beverage and water consumption, and set up schedules' for water delivery and blood and urine sample collections. The current pilot trial follows previous successful experience with the second (Edmonton) trial, where TCAA exposure was achieved by using the public water supply from another large Canadian city. This supply has sufficient TCAA to allow for ready detection of TCAA in urine following drinking water consumption. Ultimately, ten volunteers will be randomly assigned into each of five exposure groups using this municipal tap water source, diluted with TCAA-free bottled water to achieve tapwater concentrations of 0%, 12.5%, 25%, 50% and 100%, respectively. Each participant is provided details of the study design and provides informed consent prior to participation. The current pilot study of eight participants is being performed to verify the feasibility of all of the logistics of the protocol for the large study cohort of fifty. The total exposure period is 15 days. The first urine morning samples are collected on days 1, 2, 8, 14, 15 and 16 immediately after tap water consumption. Whole blood samples are collected on days 1, 8, 14 and 15. TCAA and chloral hydrate (CH) are analyzed in all urine and whole blood samples as well as in tap water samples from each exposure group. Serum and urine samples are collected for measurement of creatinine in order to correct for variation of urinary volume. The TCAA analytical methodology is performed by liquid-liquid microextraction (LLME), head-space solid phase microextraction (SPME), gas chromatography (GC) and electron capture detector (ECD). Liquid-liquid extraction (LLE), GC and ECD methods are used for the analysis of THMs (trihalomethane), HANs (haloacetonitrile), HKs (haloketone), CH (chloral hydrate) and CP (chloropicrin). The pilot trial has functioned well and the analytical data are being reviewed to determine the most appropriate dilution levels for the main study. The pilot study population of ten participants provides a reasonable basis for evaluating the practical problems inevitably experienced with an ambitious experiment with human volunteers. This study protocol appears to provide a practical and viable approach to validating urinary TCAA as a biomarker of non-volatile DBP exposure via drinking water.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,026 | 0,014 |
| Méta-épidémiologie (sens strict) | 0,002 | 0,001 |
| Méta-épidémiologie (sens large) | 0,002 | 0,003 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,002 | 0,002 |
| Communication savante | 0,002 | 0,001 |
| Science ouverte | 0,002 | 0,001 |
| Intégrité de la recherche | 0,004 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,004 | 0,001 |
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 ».