With a share of almost eight percent, aluminum is the most common metallic element in the earth's crust. Only the elements oxygen and silicon are more common. Aluminum is mainly found in aluminum silicates, hydroxides, phosphates and sulfates as well as cryolite (WHO, 1997). From the bedrock, aluminum enters soil and water through natural erosion processes and through human activities. Aluminum is a constituent of clay minerals in soil. Plants take up aluminum from soil and water, resulting in a natural aluminum content in plants and plant foods.

Metallic aluminum is produced from bauxite (an aluminum ore) in an electrolytic process and can be further processed into various alloys. In addition, various inorganic and organic aluminum compounds are produced and used in a variety of ways. Among other things, we encounter aluminum in water treatment, paper manufacturing, fire-retardant materials, household items, tableware, food packaging, food additives, dyes, feed additives, pesticides, cosmetic products and medicines.

In keeping with its diverse use, the amount of aluminum ingested by consumers (exposure) also varies widely depending on individual habits. Sources of aluminum include not only food, but also food contact materials, cosmetics, and pharmaceuticals. Aluminum can be absorbed orally (through food) and dermally (through the skin, e.g., via cosmetics) as well as inhalationally (through the respiratory tract).

Food

The aluminum in our food is a result of both the natural aluminum content of plants and the use of aluminum-containing food additives. The European Food Safety Authority(EFSA) evaluated EU-wide survey data on aluminum in food in its 2008 Scientific Opinion. Most unprocessed foods contain less than 5 mg aluminum/kg. Higher concentrations (5-10 mg/kg on average) occur in cereal products, baked goods, dairy products, and some vegetables, offal, and seafood. Average concentrations above 10 mg/kg have been measured in cocoa, tea, and herbs. However, these total aluminum levels do not allow conclusions to be drawn about specific sources of inputs, i.e., no distinction was made between natural levels and inputs from processing(EFSA 2008). Lye pastries can also contain high levels of aluminum. Drinking water, on the other hand, is a minor contributor.

Food contact materials

Because of their good thermal conductivity and light weight, some cooking or kitchen utensils, such as certain pans, espresso pots, and baking sheets, are made of aluminum alloys. Aluminum is frequently found in food packaging in the form of menu trays, beverage cans, foils or in multilayer composites. In the packaging sector, aluminum is also used because of its excellent barrier properties. On the one hand, these ensure optimum flavor protection of the food and, on the other, prevent the penetration of undesirable substances. Furthermore, aluminum is also used in metal alloys and in color pigments.

Small amounts of aluminum can transfer from food contact materials to the food during storage or preparation. However, since most food contact materials made of aluminum are additionally coated, this usually does not represent a relevant exposure. It should be noted, however, that uncoated aluminum items such as grill cups or uncoated baking sheets should not come into contact with highly acidic or highly salty foods (e.g., lemon, sauerkraut, tomatoes, barbecue marinades).

Cosmetic products

Aluminum is used in various cosmetic products. It is used as a metallic pigment for coloration in lipsticks, eye shadows or other decorative cosmetics. In sunscreens, aluminum is used to coat UV filters such as titanium dioxide. In toothpaste, aluminum compounds are used, for example, to prevent tooth decay or to remove plaque. In the form of aluminum chloride, aluminum chlorohydrate or the various aluminum-zirconium complexes (generally "aluminum salts"), it is used as an antiperspirant ingredient in antiperspirants. This distinguishes antiperspirants from deodorants, which contain only antibacterial substances and fragrances to stop unpleasant perspiration odors. Natural deodorants" are also generally based on the use of aluminum sulfates (alum stone, ammonium alum). Based on current data, antiperspirants contribute very little to the overall intake of aluminum.

The Scientific Committee on Consumer Safety (SCCS) published an assessment of aluminum in cosmetics in 2023. This included a realistic scenario in which both the intake of aluminum via cosmetics and the intake of aluminum via food and drugs were evaluated. The assessment showed that aluminum intake via food and cosmetics could be in the same order of magnitude.

Occupational exposure during aluminum production is classified as carcinogenic to humans (Group 1) according to the International Agency for Research on Cancer (IARC). This means that there is sufficient evidence to confirm with reasonable certainty a bladder cancer and lung cancer causing effect in humans from exposure during aluminum production (IARC, 2005). These carcinogenic effects of aluminum are due to inhalation exposure (i.e., uptake via the respiratory tract). With respect to oral exposure, EFSA concluded in 2008 that aluminum is not carcinogenic at doses supplied through the diet (EFSA, 2008).

Aluminum can damage the nervous system, which has been demonstrated using dialysis patients. These were chronically exposed to very high doses of aluminum directly through the bloodstream due to their treatment and developed dialysis encephalopathy, which is characterized by brain damage as well as bone mineralization disturbance and anemia. Animal studies also indicate negative effects on fertility (including sperm quality) and offspring development (e.g., motor disorders and delayed onset of puberty).

Legal regulations

Food

So far, there is no legally defined EU maximum content for aluminum in food. In January 2016, an action value of 10 mg aluminum per kg of lye pastry was issued in Austria (BMSGPK-2021-0.359.197 of 5.7.2021). An action value indicates the need for a detailed investigation or clarification. It does not represent a limit value or regulatory maximum content.

Cosmetic products

At EU level, the content of aluminum compounds in cosmetic products such as aluminum-zirconium complexes is regulated by the Cosmetics Regulation (No. 1223/2009).

Food contact materials

There are currently no legally binding limits for contact materials and articles made of metals or alloys. However, the Council of Europe technical guideline "Metals and alloys used in food contact materials and articles" (1st Edition) is recognized throughout Europe and has the status of a national regulation in some other member states. In this guideline, a maximum value of 5 mg/kg food simulant is recommended for aluminum, i.e. no more than 5 mg of aluminum per kg of food or filling material should dissolve out of the article and pass into the food during use.

Regarding the use of aluminum in commodities, there is a national recommendation from the Ministry of Health (BMG-75210/0035-II/B/13/2015 dated 27/1/2016). This states: "For the preparation and storage of highly acidic or highly saline foods (e.g. lemon, sauerkraut, tomatoes, barbecue marinades), cookware or objects made of untreated (uncoated) aluminum should not be used because of the high aluminum release to be expected. This also applies to aluminum foil used to cover acidic or salty foods in contact with food."

Investigations

We regularly investigate aluminum in various commodity groups, food contact materials and cosmetic products as part of focus campaigns.

Children's food

Young children are generally considered a particularly sensitive population group. Consequently, we have carried out monitoring of aluminum levels in children's foods. The studies on children's foods showed that they contain extremely low levels of aluminum. The average content was 1.7 mg/kg, with infant formula and follow-on formula having average contents of 0.8 and 1.2 mg/kg, respectively. Baby meals and cereal-based complementary foods each had mean levels of 1.3 and 3.4 mg/kg. The slightly higher aluminum content of the cereal-based baby food is due to the generally higher contamination of cereals with aluminum.

Glass noodles

Following increased recalls of glass noodles within the European Community due to unusually high aluminum content, two focus actions on aluminum in glass noodles were conducted. In general, glass noodles are noodles made only from the starch of mung beans, peas or similar. In the first action, out of a total of 31 samples, two were objected due to excessive aluminum content. In the absence of a legal maximum content, these objections were made on the basis of a risk analysis, since consumption of the samples would already have resulted in the maximum tolerable weekly intake (TWI 1 mg/kg body weight per week, EFSA 2008) being exceeded. Since both samples were obtained from sweet potato starch, the action was repeated with focus on such products. In the second action, no objections were raised due to elevated aluminum content.

Pretzel pastries

Lye pastries and similar baked goods are treated with caustic soda (2 to 6%) before the baking process to give them a brown crust and the typical taste during baking. For this purpose, the dough pieces are dipped into the lye and then placed on the baking tray and baked. Aluminum trays are often used for baking. These have a high thermal conductivity and are relatively corrosion resistant. However, if the caustic soda comes into direct contact with the aluminum, the protective oxide layer of the aluminum sheet is attacked. Aluminum is dissolved from the sheet and can transfer to the lye pastry. Tests have repeatedly found aluminum contents in lye pastries of more than 10 mg per kilogram of food. As early as 2002, the German Federal Institute for Risk Assessment (BfR, 2002) therefore recommended reducing the transfer of aluminum to technically unavoidable levels. This could be done, for example, by dispensing with complete dipping of the dough piece and instead only partially coating the surface with the caustic soda solution. The use of silicone liners, baking paper or non-stick coating for the aluminum sheets also help to avoid or reduce the aluminum transfer. Aluminum contents of 5 -10 mg / kg occur in bread and pastries in general, as they are naturally present in the grain. Higher contents (> 10 mg/kg), on the other hand, are considered technically avoidable and should not occur (BfR 2002, 2020; EFSA 2008).

We conducted a monitoring campaign on aluminum in pretzel pastries between the beginning of February 2015 and the end of July 2015. The purpose of this monitoring was to determine common aluminum levels in lye pastries in Austria and, if necessary, to initiate measures to eliminate sources of contamination in the manufacturing process. A total of 76 lye pastries from the various Austrian provinces were sampled during the focal action. More than 75 percent of the samples (59 samples) had aluminum levels below 10 mg/kg, while about 20 percent (15 samples) had elevated levels (10 - 90 mg/kg). In addition, two further samples (2.6%) were rejected on the basis of a risk analysis due to a highly excessive aluminum content (> 90 mg/kg).

Additives containing aluminum

Since EFSA reduced the tolerable weekly intake (TWI) from 7 mg/kg body weight to 1 mg/kg body weight in 2008, VO No. 380/2012 and 231/2012 amended the conditions of use and reduced the use levels for aluminum-containing food additives, including aluminum varnishes. In order to check the aluminum-containing additives available on the Austrian market for their conformity with these legal regulations, we carried out a focal action in this regard in 2015. A total of 32 samples were examined, including pure additives and additive mixtures, as well as ready-to-eat foods with the corresponding additives. All samples tested complied with the new legal regulations on food additives and colorants from aluminum paints with regard to aluminum content.

Food contact materials

We carried out two focus actions in 2015 with regard to the material transfer of aluminum from food contact materials. In one focus action, the aluminum transfer from cans to the filling material was investigated. In principle, beverage cans are coated on the inside so that direct food contact should not be possible. Beers, as well as carbonated beverages such as shandy, soft drinks, etc. were investigated. Initially, the aluminum content of the tank product (in production) was determined, and subsequently also after canning after a storage period of 6 and 12 months. In addition, the aluminum migration of the empty cans was determined using food simulants. The results show that the cans can release aluminum, particularly in the case of acidic beverages and longer storage periods, despite being coated. This means that the protection provided by the coating may weaken in the long term. However, the maximum value of 5 mg/kg of food set by the Council of Europe was not exceeded in any case.

Furthermore, we carried out a focus action on the transfer of aluminum from tableware and cookware. The results showed that baking pans and grill cups in particular significantly exceed 5 mg/kg when exposed to heat and acid at the same time. However, according to the manufacturer's information, these products are also not suitable for products containing acid or high levels of salt.

According to the results of a study by the BfR, aluminum migration from commercially available, uncoated aluminum menu trays also exceeds 5 mg/kg of food after a two-hour holding phase (BfR 2017).

Cosmetic products

In 2015, a focal action on aluminum in cosmetics was carried out as part of the national control plan to obtain an overview of the usual use levels in the various areas of application. Among other things, 25 antiperspirants and two deodorants were also examined here. The deodorant samples did not contain any aluminum. The antiperspirants had aluminum contents of between 0.2 and 5.8%, with the majority of samples in the 2-3% range.

Based on the available data, EFSA derived a weekly tolerable intake of 1 mg aluminum/kg body weight (the so-called "Tolerable Weekly Intake" TWI). Based on current knowledge, this amount can be ingested weekly over a lifetime without posing a health risk to humans.

EFSA's 2008 exposure assessment found that the average population with a weekly intake of 0.2 - 1.5 mg of aluminum per kg body weight exceeds the TWI of 1 mg per kg body weight by a significant proportion of the population. The largest contributors to dietary aluminum exposure were cereal products, vegetables, and beverages. The exposure levels determined by EFSA in 2008 included inputs from food additives and food contact materials in addition to natural aluminum levels in foods (EFSA 2008).

The vast majority of aluminum contained in foods passes through the gastrointestinal tract without being absorbed. On average, only about 0.1% of the aluminum in food and 0.3% of the aluminum in drinking water is absorbed through the intestinal wall. This is because although aluminum dissolves from most foods in the stomach (acidic pH), it precipitates again in the intestine (neutral pH) and thus cannot be absorbed. However, aluminum absorption from individual meals can vary greatly because different ingredients in the food can either promote or reduce absorption. Aluminum absorbed through the intestine is distributed throughout the body (in particular, e.g., higher concentrations of aluminum are present in cooking and kidneys), where it may remain for an extended period of time, and is eventually excreted through the kidneys.

Aluminum in food contact materials

Aluminum is relatively resistant to corrosion because the surface immediately forms a thin layer of aluminum oxide upon contact with oxygen, which protects the pure aluminum underneath from further oxidation and chemical attack. Nevertheless, aluminum is attacked by acidic (e.g. lemon, sauerkraut, tomatoes, sour fruit, barbecue marinades), salty and basic foods (e.g. in the production of lye pastries), which releases dissolved aluminum. For such applications, coatings made of a different material are therefore required on the food side. In addition, the aluminum housing of the coffee capsules is also coated with a plastic layer on the inside, which prevents aluminum release.

Aluminum-containing antiperspirants and breast cancer

For some time, a link between the use of antiperspirants and the incidence of breast cancer has been suspected. Studies showed that aluminum was found in the breast, mammary glands, and near the axilla in breast cancer patients (Exley et al. 2007). However, it is unclear whether this was from antiperspirant use or due to the ability of the altered cells to concentrate aluminum from the body.

A study published in 2017 by the Medical University of Innsbruck showed that breast cancer patients more often testified to having used "underarm cosmetics" several times a day at a young age (<30) compared to healthy subjects (Linhart et al. 2017). Furthermore, aluminum was detected in the breast tissue of healthy women as well as women with breast cancer, with higher aluminum concentrations in the diseased women. The amount of stored aluminum correlated with the frequency of use. However, due to the study design (case-control study), no causal relationship between aluminum salts as such and breast cancer could be established. In addition, this study showed that breast cancer of close relatives was the major risk factor.

Authors of a review article from 2008 and also epidemiological studies as well as the French health agency (Afssaps) concluded that there is insufficient data to establish a clear link between breast cancer and antiperspirants containing aluminum (Mirick et al. 2002, Namer et al. 2008, ANSM 2011).

Very little is known to date about the absorption of aluminum from antiperspirants through the skin. From a human study on two volunteers, an uptake via the skin of 0.014% was derived (Flarend et al. 2001). From an in vitro study with human skin, depending on the type of application (deodorant spray, roller, stick), uptake of a maximum of 0.96 % was derived. In the case of damaged skin, an uptake of up to 5.8 % was demonstrated here (Pineau et al. 2012). Currently, there are three human studies on the dermal bioavailability of aluminum from antiperspirants containing aluminum chlorohydrate, the results of which vary widely. Since the most recent of these three human studies provides the most reliable value for the bioavailability of aluminum, this value was used for the latest BfR calculations (BfR 2020). The result of the current BfR calculations is that adverse health effects from the regular use of antiperspirants containing aluminum chlorohydrate are unlikely according to the current state of knowledge. Consequently, the contribution of aluminum-containing antiperspirants to the overall exposure to aluminum is significantly lower than previously assumed. Since the number of subjects in the study used for the BfR calculations is relatively low at six, further meaningful studies are necessary.

Overall, due to the different results, further research is needed to better understand the uptake of aluminum after application to the skin and to clarify a possible role of aluminum in breast cell changes.

Aluminum and Alzheimer's disease

Based on the proven neurotoxicity of aluminum as well as studies on Alzheimer's disease patients who showed elevated aluminum concentrations in the brain, the hypothesis arose that aluminum was involved in the development of Alzheimer's disease. However, EFSA concluded that dietary aluminum intake does not increase the risk of Alzheimer's disease (EFSA 2008). The German Federal Institute for Risk Assessment came to a similar conclusion regarding a possible link between aluminum from consumer products and Alzheimer's disease. They, too, could not prove a connection between an increased aluminum intake and Alzheimer's disease (BfR 2007).