Aluminium levels in Canadian infant formulate and estimation of aluminium intakes from formulae by infants 0-3 months old

Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

Lead, cadmium and aluminum in Canadian infant formulae, oral electrolytes and glucose solutions

Lead (Pb), cadmium (Cd) and aluminum (Al) were determined in 437 individual samples of infant formulae, oral electrolytes and 5% glucose solutions available in Canada. In the electrolytes, Cd and Pb concentrations were all below 0.01 and 0.041 ng g⁻¹, respectively. In the 5% glucose solutions, Pb and Cd levels averaged 0.01 and 0.09 ng g⁻¹, respectively. Reported on an as-consumed basis, Pb levels in milk- and soya-based formulae averaged 0.90 and 1.45 ng g⁻¹, respectively, while Cd levels averaged 0.23 and 1.18 ng g⁻¹, respectively Average Al levels on an as-consumed basis were 440 ng g⁻¹ (range 10–3400 ng g⁻¹) in milk-based formulae and 730 ng g⁻¹ (range 230–1100 ng g⁻¹) in soy-based formulae. Al concentrations increased in the following order: plain formula < low-iron formula < iron-supplemented formula < casein hydrolysate formula ≈ premature formula ≤ soy formula. For example, in the powdered formulae, average Al concentrations were 18 ng g⁻¹ for plain milk-based, 37 ng g⁻¹ for low-iron, 128 ng g⁻¹ for iron supplemented, 462 ng g⁻¹ for lactose-free, 518 ng g⁻¹ for hypoallergenic and 619 ng g⁻¹ for soy-based formula. Al concentrations, as-consumed, increased with decreasing levels of concentration: powder < concentrated liquid < ready-to-use. Formulae stored in glass bottles contained between 100 and 300 ng g⁻¹ more Al than the same formulae stored in cans. The source of the increased Al did not appear to be the glass itself, because most electrolytes and glucose solutions, also stored in glass, contained less than 8 ng g⁻¹ Al. Corresponding differences in Pb and Cd levels were not observed. Al concentrations varied substantially among manufacturers; however, all manufacturers were able to produce plain milk-based formulae containing less than 50 ng g⁻¹ Al, i.e. within the range of Al concentrations found in human milk. Next to soya-based and hypoallergenic formulae, premature formulae contained among the highest concentrations of Al, ranging 851–909 ng g⁻¹ from one manufacturer and 365–461 ng g⁻¹ from another.

Dietary and other sources of aluminium intake

Aluminium in the food supply comes from natural sources including water, food additives, and contamination by aluminium utensils and containers. Most unprocessed foods, except for certain herbs and tea leaves, contain low (< 5 micrograms Al/g) levels of aluminium. Thus most adults consume 1-10 mg aluminium daily from natural sources. Cooking in aluminium containers often results in statistically significant, but not practically important, increases in the aluminium content of foods. Intake of aluminium from food additives varies greatly (0 to 95 mg Al daily) among residents in North America, with the median intake for adults being about 24 mg daily. Generally, the intake of aluminium from foods is less than 1% of that consumed by individuals using aluminium-containing pharmaceuticals. Currently the real scientific question is not the amount of aluminium in foods but the availability of the aluminium in foods and the sensitivity of some population groups to aluminium. Several dietary factors, including citrate, may affect the absorption of aluminium. Aluminium contamination of soy-based formulae when fed to premature infants with impaired kidney function and aluminium contamination of components of parenteral solutions (i.e. albumin, calcium and phosphorus salts) are of concern.

Aluminium content of some foods and food products in the USA, with aluminium food additives

The primary objective was to determine the aluminium (Al) content of selected foods and food products in the USA which contain Al as an approved food additive. Intake of Al from the labeled serving size of each food product was calculated. The samples were acid or base digested and analysed for Al using electrothermal atomic absorption spectrometry. Quality control (QC) samples, with matrices matching the samples, were generated and used to verify the Al determinations. Food product Al content ranged from <1-27,000 mg kg(-1). Cheese in a serving of frozen pizzas had up to 14 mg of Al, from basic sodium aluminium phosphate; whereas the same amount of cheese in a ready-to-eat restaurant pizza provided 0.03-0.09 mg. Many single serving packets of non-dairy creamer had approximately 50-600 mg Al kg(-1) as sodium aluminosilicate, providing up to 1.5 mg Al per serving. Many single serving packets of salt also had sodium aluminosilicate as an additive, but the Al content was less than in single-serving non-dairy creamer packets. Acidic sodium aluminium phosphate was present in many food products, pancakes and waffles. Baking powder, some pancake/waffle mixes and frozen products, and ready-to-eat pancakes provided the most Al of the foods tested; up to 180 mg/serving. Many products provide a significant amount of Al compared to the typical intake of 3-12 mg/day reported from dietary Al studies conducted in many countries.

Aluminium content of Spanish infant formula

Levels of aluminium in 82 different infant formulae from nine different manufacturers in Spain were determined by acid-microwave digestion and graphite furnace atomic absorption spectrophotometry. The influence of aluminium content in tap water in reconstituted powder formulae was examined and an estimate was made of the theoretical toxic aluminium intake in comparison with the provisional tolerable weekly intake (PTWI). Possible interactions between aluminium and certain essential trace elements added to infant formulations have been studied according to the type or main protein-based infant formula. In general, the infant formulae contained a higher aluminium content than that found in human milk, especially in the case of soya, preterm or hydrolysed casein-based formulae. Standard formulae gave lower aluminium intakes amounting to about 4% PTWI. Specialized and preterm formulae resulted in a moderate intake (11-12 and 8-10% PTWI, respectively) and soya formulae contributed the highest intake (15% PTWI). Aluminium exposure from drinking water used for powder formula reconstitution was not considered a potential risk. In accordance with the present state of knowledge about aluminium toxicity, it seems prudent to call for continued efforts to standardize routine quality control and reduce aluminium levels in infant formula as well as to keep the aluminium concentration under 300 microg l(-1) for all infant formulae, most specifically those formulae for premature and low birth neonates.

Determination of mineral contents in different kinds of milk and estimation of dietary intake in infants

Concentrations of 11 minerals were determined in six kinds of milk (cow's milk-based formulae, breast-milk, soya milk, bottled milk, dried milk and evaporated milk). The contents of copper, magnesium, molybdenum, aluminium, barium and nickel were higher in soya milk than in any other kinds of milk. Except for nickel in soya milk, the dietary intakes of minerals were below or close to the intake recommended by the FAO/WHO.

Aluminum exposure and metabolism

Aluminum (Al) is a nonessential, toxic metal to which humans are frequently exposed. Oral exposure to aluminum occurs through ingestion of aluminum-containing pharmaceuticals and to a lesser extent foods and water. Parenteral exposure to aluminum can occur via contaminated total parenteral nutrition (TPN), intravenous (i.v.) solutions, or contaminated dialysates. Inhalation exposure may be important in some occupational settings. The gut is the most effective organ in preventing tissue aluminum accumulation after oral exposure. Typically gastrointestinal absorption of aluminum from diets is < 1%. Although the mechanisms of aluminum absorption have not been elucidated, both passive and active transcellular processes and paracellular transport are believed to occur. Aluminum and calcium may share some absorptive pathways. Aluminum absorption is also affected by the speciation of aluminum and a variety of other substances, including citrate, in the gut milieu. Not all absorbed or parenterally delivered aluminum is excreted in urine. Low glomerular filtration of aluminum reflects that most aluminum in plasma is nonfiltrable because of complexation to proteins, predominantly transferrin. The importance of biliary secretion of aluminum is debatable and the mechanism(s) is poorly understood and appears to be saturable by fairly low oral doses of aluminum.

Neurodevelopmental effect of aluminum in mice: fostering studies

In order to determine sensitive periods for induction of neurodevelopmental effects of aluminum (Al), mice were fed either 25 (control) or 1000 (high Al) micrograms Al/g diet (as Al lactate) from conception through lactation and litters were fostered either within or between groups at birth. Birth parameters were not influenced by Al intake. Food intake and body weight were 10%-12% lower during lactation in dams fed the high Al diets. Both gestation and lactation high Al exposure led to growth retardation in offspring beginning on day 10 postnatal; combined gestation and lactation exposure led to the biggest weight differential at weaning (23%). For neurobehavioral measures obtained at weaning, forelimb grasp strength was influenced by gestation high Al exposure, whereas negative geotaxis was influenced by lactation exposure, and hindlimb grasp and temperature sensitivity were influenced by both gestation and lactation exposure. Pup liver and brain manganese (Mn) and liver iron (Fe) concentrations at weaning were lower after high Al lactation exposure than in controls. Pup brain and liver Al concentrations were similar among the groups. These data show that mice are susceptible to neurodevelopmental effects of high maternal dietary Al intake during both gestation and lactation, and that high maternal intake can result in altered essential trace element metabolism in the offspring.

Aluminium levels in milk and infant formulae

Aluminium levels in infant formulae purchased in 1990 and prepared as for consumption were in the range 530 micrograms/l to 640 micrograms/l for soya-based products and 27 micrograms/l to 120 micrograms/l for cows' milk-based formulae. Mean aluminium concentrations in these soya and cows' milk-based samples were, on average, 37% and 45% lower, respectively, than those of the same brands purchased between 1985 and 1987. Levels of aluminium in breast milk were in the range 3 micrograms/l to 79 micrograms/l. In the case of retail cows' milk, values ranged from 4 micrograms/l to 33 micrograms/l whilst more variable amounts of between 5 micrograms/l and 285 micrograms/l were detected in retail soya milk.