Human metabolism of aluminium-26 and gallium-67 injected as citrates

Abstract

<jats:p> 1 <jats:sup>26</jats:sup>Al and <jats:sup>67</jats:sup>Ga were given as citrates to a healthy male volunteer by intravenous injection. The retention of both tracers was studied by body radioactivity measurement. Levels in blood and excreta were determined by y-ray spectrometry and/or accelerator mass spectrometry. </jats:p><jats:p> 2 More than half of the <jats:sup>26</jats:sup>Al had left the blood after 15 min and the decline continued, leaving &lt;1% in blood after 2 d; the losses occurred both to renal excretion and through uptake by other compartments. Estimated excre tion up to 13 d was 83% (urine) and 1.8% (faeces). Whole-body retention of 15% at 13 d declined to ∼4% at 1178 d, when the daily reduction corresponded to a bio logical half-life of 7 y, suggesting that sustained intake of dietary aluminium may lead to a progressively increas ing internal deposit. </jats:p><jats:p> 3 The metabolism of <jats:sup>67</jats:sup>Ga differed markedly from that of <jats:sup>26</jats:sup>Al in all aspects studied. </jats:p>

The biological speciation and toxicokinetics of aluminum.

“…A 41-year-old male volunteer given 26Al intravenously as aluminum citrate excreted all but 10-15% of the aluminum during the first day (31). However, 7% of the aluminum remained 170 days after the injection, at which time the authors estimated the clearance half-time to be >1 year.…”

“…Xu et al (94) found that biliary excretion accounted for <1% of the aluminum administered as the sulfate to rats, whereas urinary elimination accounted for 9-17%. Greater than 80% of an intravenous dose of Al citrate was eliminated in the urine of a human within 2 weeks, whereas <2% appeared in the feces (31). The relative contributions of each route of excretion depend in part on such factors as the solubility of aluminum species, presence of complexing ions in serum, renal competence, and aluminum dose.…”

Aluminum in Food – The Nature and Contribution of Food Additives

“…Aluminum in lung may be from environmentally-derived particles, occupational exposure, and distribution from blood. Approximately 80% of an intravenous dose of aluminum citrate was excreted within a week, suggesting the remainder was retained within the body, some of which was excreted over a longer time (Priest et al 1995). This indicates that Al accumulates in the body during continuous intake, even in subjects with normal renal function.…”

Use of accelerator mass spectrometry for studies in nutrition

“…AMS measurements have shown that 67 Ga is a good surrogate for cell culture studies (Dobson et al 1998), but is not to be trusted in metabolism studies with rats or human subjects Priest et al 1995). Thus, 26 Al is an invaluable tool in metabolism studies.…”