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Aluminium occurs naturally in the environment, and is the most abundant metallic element in the earth’s crust. The naturally occurring stable isotope is 27Al. The isotope 26Al has a long half life but a low natural abundance and is used as a tracer in biological studies. Aluminium is found in nature only as the ionic Al3+. A variety of aluminium compounds are produced and used for different purposes, such as in water treatment, papermaking, fire retardant, fillers, food additives, colours and pharmaceuticals. Aluminium metal, mainly in the form of alloys with other metals, has many uses including in consumer appliances, food packaging and cookware.
Based on the available scientific data the EFSA Panel 1 does not consider exposure to aluminium via food to constitute a risk for developing Alzheimer’s disease despite the fact it has been suggested that aluminium could be implicated in the aetiology of Alzheimer and other neuro-degenerative diseases.
This despite the fact it has been suggested that aluminium could be implicated in the aetiology of Alzheimer and other neuro-degenerative diseases. This included the evaluation of a study of 2011 on the oral absorption of various aluminium compounds whose results did not provide any additional information that could modify their conclusions reached in 2008.
Although at high levels of exposure, some aluminium compounds may produce DNA damage, the Panel considered this unlikely to be of relevance for humans and also concluded that aluminium is unlikely to be a human carcinogen at dietary relevant doses.
On basis of these conclusions of EFSA, the French Agency AFSSAPS evaluated in 2011 the exposure and the potential health effects related to dermal exposure and concluded that there are insufficient data to establish a clear relationship between the use of underarm aluminum-based antiperspirants and breast cancer.
Sources are considered with regards to the two main routes of exposure : oral and dermal.
Dietary sources
The major route of exposure to aluminium for the general population is through food. Most unprocessed foods typically contain less than 5 mg aluminium/kg but higher concentrations (mean levels 5 to 10 mg/kg) were often found in breads, cakes and pastries (with biscuits having the highest levels), as well as some vegetables (with mushrooms, spinach, radish, …). Cereals and cereal products, vegetables, beverages and certain infant formulae appear to be the main contributors to the dietary aluminium exposure.
Meanwhile, it is not possible, says the report, to establish a detailed breakdown by exposure source contributing to the aluminium content of a particular food, which include the amount inherently present in the food, the contributions from use of food additives, and the amounts released to the food during processing and storage from aluminium-containing foils, containers, or utensils. Aluminium in drinking water represents another minor source of exposure and additional exposures may arise from the use of aluminium compounds in pharmaceuticals and consumer products.
Dermal exposure
The absorption of aluminum after dermal exposure is very poorly understood, says the AFFSAPS report, as the available studies are of poor quality and are not carried out according to the current requirements. Meanwhile, recent in vitro study on human skin via two scenarios (intact and damaged skin) allowed to estimate the dermal absorption of aluminum via a daily exposure to an antiperspirant containing 20% of aluminum chlorohydrate (5% aluminum). The exposure of intact skin would lead to a dermal absorption rate of 0.5% while exposure of damaged skin would result in an absorption rate of 18%.
In this context, AFSSAPS recommends to restrict the concentration of aluminum in cosmetic products at 0.6% and not to use cosmetics containing aluminum on damaged skin.
The absorption, distribution and elimination properties of aluminium (called its “bioavailability”) and several aluminium compounds in humans and experimental animals have been reviewed extensively and summarized in the EFSA report. Available studies indicate that the oral bioavailability of aluminium in humans and experimental animals from drinking water is approximately 0.3%, whereas the bioavailability of aluminium from food and beverages generally is considered to be lower, about 0.1%. However, it is likely, says the report, that the oral absorption of aluminium from food can vary at least 10-fold depending on the chemical forms present in the intestinal tract. Globally, the total body burden of aluminium in healthy human subjects has been reported in Europe to be approximately 30–50 mg/kg bw. Absorbed aluminium is eliminated primarily by the kidneys, presumably as aluminium citrate, and excreted in the urine. Unabsorbed aluminium is excreted in the faeces.
The results from a more recent study (2011) 3 showed that the oral bioavailability of aluminium from twelve different aluminium-containing compounds, including food additives falls within the overall 10-fold range of previously reported oral bioavailability values for aluminium containing compounds. Therefore, EFSA considered that the new study does not provide any additional information that could modify the conclusions reached in 2008 and does not give reason to reconsider the previous safety evaluation of aluminium-based food additives authorised in the European Union.
The Panel considered it prudent to take into account, when setting a tolerable intake for all dietary sources, that several compounds containing aluminium showed in experimental tests in animals the potential to produce neurotoxicity, to affect the male reproductive system and, after maternal exposure, have shown embryotoxicity and have affected the developing nervous system in the offspring.
It is in view of the cumulative nature of aluminium in the organism after dietary exposure that the EFSA Panel considered it more appropriate to establish a Tolerable Weekly Intake (TWI) for aluminium rather than a Tolerable Daily Intake (TDI). Based on the combined evidence from the available studies, the Panel established a TWI of 1 mg aluminium/kg body weight/week.
The limit of 1 mg aluminium / kg body weight / week is in line with that set in 2006 by the Joint FAO / WHO (JEFCA) expert committee 5, which had already reassessed the 1989 Provisional Tolerable Weekly Intake (PTWI) based on studies particularly cited by IPCS (1997) and TOC 5 (2005).
To assess the maximum tolerable level, JECFA noted that no new data really emerged since the 1989 assessment and had retained the option to refer to the range of values (50-75 mg / kg bw / day) representative data from the literature rather than to the results of any specific study. This led to define a new TWI of 1 mg / kg bw / week (Al), value taking into account a safety factor of 100 and accompanied by an uncertainty factor of 3 for the potential for bioaccumulation. This TWI applies to all aluminum compounds present in food, including food additives.
The risk from dietary exposure
The estimated mean dietary exposure to aluminium in the general population, assessed in several European countries, was, according to the EFSA report of 2008, up to 2.3 mg/kg body weight/week in highly exposed consumers. Therefore, the Tolerable Weekly Intake of 1 mg/kg body weight/week is likely to be exceeded in a significant part of the European population
Regarding exposure data to aluminum of the French population from food, in 2008, the French Agency of Food Safety AFSA 4, showed that the potential risk of overexposure is low. Indeed, the estimated total intake alulminium, all food categories combined, remains below the Tolerable Weekly Ievel of 1 mg / kg bw / week, whatever the categories of the population concerned, including infants.
The risk from dermal exposure
For dermal exposure, a margin of safety of 11 would be ensured with regards to the tolerable weekly intake in intact skin exposure conditions but it would be less than 1 in the case of damaged skin exposure conditions.
The French agency AFSSAPS considered that their risk assessment for dermal exposure shows that exposure to antiperspirant products with concentrations of 20% aluminum chlorohydrate does not ensure consumer safety under normal conditions of use. In addition, as their present risk assessment does not take into account the total exposure to various cosmetic products likely to contain aluminum, their conclusions are subject to change. On this basis, the AFSSAPS recommends to restrict the concentration of aluminum in cosmetic products to 0.6% and not to use cosmetics containing aluminum on damaged skin. The AFSSAPS also recommends this information to be clearly indicated on the packaging.
1 European Food Safety Agency
2 Agence Française de Sécurité Sanitaire des Produits de Santé
3 Statement of EFSA on the Evaluation of a new study related to
the bioavailability of aluminium in food EFSA Journal 2011;9(5):2157
www.efsa.europa.eu/en/efsajournal/pub/2157.htm
4 67th report of the joint FAO/WHO expert Committee on
food additive. Evaluation of certain food additives and contaminants. WHO
Technical Report Series 940 (Rome
2006)
5
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