Foodborne exposure to aluminium

Aluminium's occurrence in food is a result of its natural occurrence in the environment and its dispersion via industrial uses.

Because of its numerous useful physical and chemical properties (malleability, high electrical and chemical conductivity, low density, etc.), aluminium is a metal which finds applications in many industries and activities:

• construction and transportation;
• agro-foods (preservation, colouring, additives, etc.), packaging (beverage and food containers, etc.), manufacturing of kitchen utensils;
• pharmaceutical industry (gastric cytoprotectants, antacids, vaccine adjuvants, pharmaceutical glassware, etc.);
• surgery (ceramics used for orthopaedic and dental surgery, alloys in orthopaedic implants, etc.);
• cosmetology (antiperspirants, hair dyes, etc.);
• drinking water treatment processes (flocculants and clarifying agents).

What are the routes through which we are exposed to aluminium?

In humans, the principal chronic exposure routes for aluminium are the oral route (food, water, oral medication), cutaneous route (cosmetics and antiperspirants) and the respiratory route (dust inhalation).

For the oral route, the general public is essentially exposed to aluminium through food, with the contribution from water totalling less than 5% of total intake.

The main foods that contribute to aluminium intake are the following:

• for infants: vegetables, milk and fruit purees;
• for children, adolescents and adults: cereal-based products, vegetables.

Aluminium-based additives in foods (such as food colouring agents, anti-caking agents, firming agents, etc.) represent a very low-level source of exposure. 

Healthcare products such as antacids and gastric cytoprotectants which contain large amounts of aluminium may during treatment expose consumers to doses well above those found in foods.

The use of cosmetics containing aluminium also contribute to exposure.

Aside from professional contexts in which workplace air may contain high levels of aluminium, inhalation is considered a minor exposure route.

Aluminium and drinking water

Aluminium may be present in drinking water due to its natural occurrence in the water supply or may be the result of the potabilisation process. During treatments for producing water intended for human consumption, aluminium salts may be used in the flocculation stage.  This treatment reduces micro-organisms in the water (bacteria, viruses, parasites), improves water colour and turbidity and provides water quality which ensures the efficacy of the disinfection stage.

However, if potabilisation treatments are performed correctly, the aluminium used in the process is eliminated directly after its use.

Treatment facilities which use aluminium must be designed and operated in such a way that they can continually ensure compliance with the French quality standard set at 200 µg/L in accordance with WHO recommendations.

Since 2004, the monitoring of aluminium in municipal water supplies is reinforced when aluminium is used in the water treatment process.

Over the last six years, the rate of exceedence of the quality reference standards for water has dropped: 2.8% of the periodical analyses indexed in the SISE-Eaux database^[1] between 1999 and 2003 versus 1.8% between 2003 and 2009.

Aluminium toxicity

The toxic effects of aluminium mainly concern the central nervous system (encephalopathies, psychomotor disorders) and bone tissue.

The proven clinical effects of aluminium have regularly been observed in situations of high chronic exposure: kidney failure patients on dialysis, parenteral nutrition, people exposed in an occupational context.In workers toxicity is mainly observed in the lungs and nervous system. 

However currently no studies have shown any such effects in the general public exposed through ordinary diet or health products.

In 2008, EFSA^[2] also set a Provisional tolerable weekly intake (PTWI)of 1 mg/kg bw/week (7 times lower than the previous DHTP). In 2011, the JECFA^[3] raised the value previously set in 2006 by establishing a PTWI of 2 mg/kg bw/week. This PTWI applies to all the aluminium compounds found in foods.

What is ANSES doing about aluminium?

Following a joint report we published along with the INVS and AFSSAPS (now known as ANSM) in 2003 on the assessment of the health risks of aluminium, ANSES conducted several studies on the exposure of the French population to this substance through their food, including:

The second Total Diet Study (TDS 2)

The second French Total Diet Study (TDS 2) shows that the average aluminium exposure of the French population is approximately 0.28 mg/kg bw/week in adults and 0.42 mg/kg bw/week in children (3 to 17 years old).

The TDS 2 study is the most representative study available, due to the number of foods analysed, the methodology employed (meal preparation practices as close to reality as possible) and to the increased sensitivity of the analysis methods used.

Average French exposure is lower than the PTWI set by EFSA (1 mg/kg bw/week). However, an analysis of the distribution of all results shows that there is a 0.2% exceedence of the PTWI in adults and a 1.6% exceedence in children (3 to 17 years old).

Due to the ubiquitous nature of aluminium in the environment, almost all foodstuffs contain a certain amount naturally, with high levels found in both cocoa and tea (50 mg/kg in chocolate).

Since TDS 2 takes into account the consumption of various products, it makes it possible to pinpoint the major aluminium contributors.For adults, the major contributors are cereal-based products (20%), vegetables (14%), and tea (11%). In children, the contribution of cereal-based products totals 27%, vegetables 12%, milk and dairy products 9%, and chocolate 5%. All the rest of intake is spread out over a large range of foodstuffs.

Water, however, is only a minor contributor, and the contribution of sodas totals only 0.4% in adults.

Infant Total Diet Study (iTDS)

In the context of the Infant Total Diet Study currently being conducted by ANSES, the concentrations in aluminium are being measured in the diets of children from 0 to 3 years of age.

The results of this study will be published in early 2015 (contingent upon the time required for sampling and analysis).

^[1]Database of the French Ministry of Health which compiles all of the health and safety monitoring results for water intended for human consumption.
^[2]EFSA, Safety of aluminium from dietary intake, EFSA Journal (2008) 754, 1-34.
^[3]Joint FAO/WHO Expert Committee on Food Additives (JECFA), Summary and conclusions of the seventy-fourth meeting, Rome, 14-23 June 2011, JECFA/74/SC.