Aluminum exposure and toxicity in neonates: sources, absorption, and retention
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Correspondence Aluminum exposure and toxicity in neonates: sources, absorption, and retention
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World J Pediatr, Vol 11 No 1 . February 15, 2015 . www.wjpch.com
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Correspondence
anni et al[1] proposed a "guide to halt aluminum overload in the prenatal and perinatal periods" focusing on "aluminum exposure and toxicity in neonates". Their review addressed aluminum overload and risk of systemic intoxication beyond special circumstances of patients receiving intravenous fluid therapy and parenteral nutrition. Fanni et al [1] are commended for bringing into perspective the immature neurologic and immunologic systems of the premature/newborn in relation to aluminum exposure during pregnancy and infancy. Although their main questions were addressed and part of the discussion was summarized in the table, the respective recommendations deserve additional comments and clarification. They urged that "neonatologists need to be much more concerned about aluminum content" that newborns may be exposed to during the first six months. They summarized total aluminum exposure from vaccines (4 mg), breast milk (10 mg), infant formula (40 mg), and soy-based formula (120 mg) in a very simple fashion, emphasizing that there is still too much aluminum in formulas. However they did not consider or discuss aluminum chemical forms, mode of exposure, bioavailability, or "biological activity". When we compare total aluminum intake derived from feeding modes (breastfeeding and formula feeding), it is crucial that we consider constitutional/intrinsic (physiological) and extrinsic (bioavailabity) issues that affect aluminum exposure. In breastfeeding, aluminum concentrations decrease from colostrum (56.5 μg/L) to transitional milk (36.6 μg/L), reaching the lowest concentration in mature milk (13.4 μg/L) at the second month.[2] While breast milk aluminum concentrations may further decrease by six months of lactation, formula feedings are constant in aluminum concentrations, and are usually taken in higher quantities than breast milk. Therefore, aluminum intake by breastfed infants is relatively less than the aluminum intake by formulafed infants. Although Fanni et al[1] mentioned factors that influence aluminum absorption ("assumption") in maternal diets, they didn't compare aluminum bioavailability in breast milk to that in formulas (cow's milk or soy based) fed to infants. Indeed, regarding total aluminum intake represented in the table, aluminum
bioavailability (or retention) constitutes the most salient feature that was missing in the otherwise excellent review. Fanni et al[1] correctly drew attention to "biologically active aluminum" but listed total aluminum exposure from vaccines (4 mg) as a fraction of the total aluminum exposures in milk feedings (10 to 120 mg). Without proper discussion, this can be incorrectly represented and understood. Indeed, an important difference exists between availability and/or reactivity of aluminum chemical forms in vaccines and infant feedings. Actually, when aluminum bio-availability (absorption and/
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