Uptake and Removal of Uranium by and from Human Teeth.
Chem Res Toxicol
; 34(3): 880-891, 2021 03 15.
Article
en En
| MEDLINE
| ID: mdl-33507734
Uranium-238 (238U), a long-lived radiometal, is widespread in the environment because of both naturally occurring processes and anthropogenic processes. The ingestion or inhalation of large amounts of U is a major threat to humans, and its toxicity is considered mostly chemical rather than radiological. Therefore, a way to remove uranium ingested by humans from uranium-contaminated water or from the air is critically needed. This study investigated the uranium uptake by hydroxyapatite (HAP), a compound found in human bone and teeth. The uptake of U by teeth is a result of U transport as dissolved uranyl (UO22+) in contaminated water, and U adsorption has been linked to delays in both tooth eruption and development. In this present work, the influence of pH, contact time, initial U concentration, and buffer solution on the uptake and removal of U in synthetic HAP was investigated and modeled. The influence of pH (pH of human saliva, 6.7-7.4) on the uptake of uranyl was negligible. Furthermore, the kinetics were extremely fast; in one second of exposure, 98% of uranyl was uptaken by HAP. The uptake followed pseudo-second-order kinetics and a Freundlich isotherm model. A 0.2 M sodium carbonate solution removed all the uranyl from HAP after 1 h. Another series of in vitro tests were performed with real teeth as targets. We found that, for a 50 mg/L U in PBS solution adjusted to physiological pH, â¼35% of the uranyl was uptaken by the tooth after 1 h, following pseudo-first-order kinetics. Among several washing solutions tested, a commercially available carbonate, as well as a commercially available fluoride solution, enabled removal of all the uranyl taken up by the teeth.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Diente
/
Uranio
Límite:
Humans
Idioma:
En
Revista:
Chem Res Toxicol
Asunto de la revista:
TOXICOLOGIA
Año:
2021
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos