Normal Aluminum Levels

Historically, aluminum has not been considered an important toxicant. With the total body burden of aluminum less than 30 mg, it was thought that the skin, gastrointestinal tract, emd lungs were effective barriers in excluding environmentfil aluminum from interned entry.  

Brain aluminum content in the humem is around 2 xg/g dry weight, with an upper limit of 4 iig/g considered the cutoff point for normed human brain. The eduminum content of other adult mammalian brains is in the seime remge.  

Like most other metals, aluminum competes for absorption from the gut with other elements. Stiff and Kelley suggest that fluoride competes with aluminum absorption from the gut, i.e., the more fluoride in the diet, the less aluminum is absorbed, and this reduces the probability of aluminum-associated behavioral toxicological conditions. Little is presently known about the functional aspects of other possible competitors with aluminum. 

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The concentration of aluminum in different foodstuffs varies from 0.05 to 129mg/kg with an average concentration of approximately 12.6mg/kg. With the exception of certain spices and tea leaves, the normal aluminum levels in foodstuffs are very low. On the contrary, the increased uptake of antimonium by humans comes from its use as a food additive. Contamination could also occur from the use of aluminum containers and aluminum cans in the food industries. Water does not constitute a significant source of aluminum uptake. 

Ingested aluminum is poorly absorbed, and there appears to be no retention of aluminum from nutritional sources in individuals with normal kidneys. Dusts of metallic aluminum and aluminum oxide are not significantly absorbed systemically, although fume from welding aluminum is absorbed through the lungs, producing a rise in aluminum levels in plasma and urine. 

The normal level of aluminum in adult human lungs is about 20 mg/kg wet weight (w/w) and increases with age due to buildup reported normal levels in human bone tissue range from 5 to 10 mg/kg (Allfey 1980 Allfey et al. 1980 Coumot-Witmer et al. 1981 Flendrig et al. 1976 Hamilton et al. 1972/73 Tipton and Cook 1963). Low aluminum levels (0.3-0.8 mg/kg w/w) are found in most soft tissue organs, other than the lungs (Hamilton et al. 1972/73 Tipton and Cook 1963). 

Hematological Effects. Hematological effects have not been observed in humans or animals with normal renal function. However, microcytic, hypochromatic anemia has been observed in individuals with impaired renal function. The anemia is unresponsive to iron therapy. The severity of the anemia correlates with plasma and erythrocyte aluminum levels and can be reversed by terminating aluminum exposure and chelation therapy with DFO. 

Normal values of aluminum in whole blood have been reported to range from 0.14 to 6.24 mg/L (ppm), and in plasma from 0.13 to 0.16 mg/L (ppm) (Sorenson et al. 1974). Normal values in serum have been reported at 1.46 and 0.24 mg/L (ppm), using neutron activation and atomic absorption analysis, respectively (Berlyne et al. 1970). A normal value of 0.037 mg/L (ppm) for serum using flameless atomic absorption analysis has also been reported (Fuchs et al. 1974). Drablos et al. (1992) analyzed aluminum serum levels in 230 nonexposed workers (controls) and reported a mean aluminum serum level of 0.005 0.002 mg/L (ppm). Research has shown that the levels of aluminum in the serum in the general population do not exceed 0.01 mg/L (ppm) (Cornells 1982). Nieboer et al. (1995) reviewed 34 studies on aluminum levels in serum or plasma, and also reported that aluminum serum levels in the general population were typically <0.01 mg/L (ppm). 

Tsou VM, Young RM, Hart MH. 1991. Elevated plasma aluminum levels in normal infants receiving antacids containing aluminum. Pediatrics 87 148-151. 

Bone aluminum level 85 times higher than controls Non-specific histological changes Brain aluminum level 0.93-1.81 pg/g dry weight (>20 times higher than normal)... 

Calcium channels are suggested to mediate intestinal aluminum absorption [84]. Aluminum distributes unequally to all tissues. The values given for the aluminum levels in the human body vary widely. Under normal conditions the aluminum concentration in blood is 5-10 pmol L-1 [14, 85]. The mean aluminum concentration in human milk was 23.4 9.6 pg L-1 and did not differ significantly between colostrum, intermediate-stage, and mature-stage milk [86]. 

Contamination. Contamination of samples by external sources can be a serious source of error and may be extremely variable. An excellent example of how serious this can be has been documented in the analysis of samples for polychlorinated biphenyls (PCBs). PCBs are synthetic mixtures of organochlorine compounds that were first manufactured in 1929 and have become of concern as significant environmental pollutants. It has been demonstrated that samples archived since 1914, before PCBs were manufactured, picked up measurable amounts of PCBs in a few hours just sitting in a modem laboratory (Erickson). Aluminum levels in the dust in a normal laboratory are so high that dust prohibits the determination of low ppb levels of aluminum in samples. A special dust-free clean lab or clean bench with a filter to remove small dust particles may be required, similar to the clean rooms needed in the semiconductor industry, for determination of traces of aluminum, silicon, and other common elements such as iron. When trace (inorganic analysis is required, the laboratory environment can be a significant source of contamination. 

Figure 5-12. XPS cove level spccira recorded during successive deposition of aluminum on PPV (adapted from 59 ). The Al(2p) spccira have been normalized in equal mcial component inlensily (ai about 72.5 eV).

A more complex example Is provided by cluster two, the alblte cluster containing mainly sodium, aluminum, and silicon. Consideration of the number of vectors from the elgenanalysls In Table III suggested the presence of four components. Target testing Identified these as alblte, quartz, orthoclase, and perhaps gypsum. The fit of these four vectors Is shown In Table V. Normalized elemental concentrations less than about 0.01 are considered unreliable because they are too close to the noise level. Thus, for example, vector one. Identified as alblte, contains only sodium, aluminum, and silicon vector two. Identified as quartz, appears to have a... 

A series of first-principles calculations of the combined system, that is, the tip and the sample, has been carried out by many authors, for example, Ciraci, Baratoff, and Batra (1990, 1990a). The three-dimensional shape of the potential barrier as well as the force between the tip and the sample are calculated. Three systems have been studied graphite-carbon, graphite-aluminum, and aluminum-aluminum. All those studies reached the same conclusion The top of the potential barrier between the tip and the sample is either very close to or lower than the Fermi level within the normal tip-sample distances of STM. 

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