Aluminium has been in close contact with our food for over a century now. It is a common practice to cook in aluminium utensils, as it has excellent heat transfer properties. As an abundantly available metal in the earth’s crust, aluminium is widely exploited for its lightweight, corrosion-resistant, inert, odourless, durable and completely recyclable qualities. It is no wonder that it finds extensive use of in food and related packaging industry which consumes aluminium on a massive scale.
A considerable chunk of rolled aluminium goes to the food processing and packaging industry which relies heavily upon the versatile metal in various forms to provide a hygienic, impermeable, odourless environment for the items to improve their shelf life. Food wrapped and cooked in foils, and, beverages stored in aluminium cans are a common sight. Trace amounts of aluminium enter our system through natural sources like water, air, grains, cereals, potatoes, spinach, soy, tea and some seafood like jellyfish. Aluminium based salts are used widely in bakery foods and confectionaries as colouring, leavening, stabilising and emulsifying agents. Along with direct ingestion, aluminium also enters our body through cosmetics and medicines like antacids and in vaccines where it is added to fire up the immune response. There are alarm bells scientists are now critically examining the impact of aluminium exposure in humans. Their observations call for attention.
Aluminium has no known biological value and is not absorbed in the body. Very few studies are available on aluminium activity in the gastrointestinal tract. However, once ingested, aluminium quickly transports to all organs. While trace amounts are expelled out through stools and urine, evidently, when in excess, the metal burdens the organs, especially the kidneys, which struggle to flush it out.
The maximum accumulation of aluminium is noticed in bones, causing rapid demineralisation leading to dystrophy and hampering the regrowth of the cells. The metal goes unnoticed in blood scans, leaving a bone biopsy as the only source of detection. Studies conducted in the past couple of decades recognise aluminium as a potent neurotoxin, and its overexposure inhibits more than 200 biologically important functions; it is found to causes adverse effects in plants, animals, and humans. Although there is much scientific debate, some studies indicate a disturbing link between aluminium exposure and Alzheimer’s, wherein the researchers found high levels of it in brain cells. Another study provides mounting evidence that aluminium may play a critical role in the protein aggregations or formation of amyloids — the chief symptom of the debilitating neurological condition. Yet other research has shown that high levels of aluminium affect reproduction and development of the foetus.
One major pathway of aluminium toxicity is found to be by leaching. Research provides insights that water and oil-based cooking in aluminium utensils adds only a minor amount of the metal, which is routinely flushed out in the body. Whereas, acidic foods cooked in aluminium pots and pans can bring about a dramatic change in leaching levels. Ready food mixes, spice powders, and beverages come in different types of aluminium packing. They are highly acidic and readily penetrate through the thin polymer coating around the metal, leaching it into the food. Moreover, the polymer itself is a source of contamination.
There is a tremendous spike in the consumption of processed foods, which is leading to a chief dietary source of aluminium exposure in humans. Frequent consumption of bakery foods is another potential route. Prolonged use of antacid and other medications that contain aluminium compounds significantly increase the toxicity. Besides, we are absorbing significant amounts of metal from cosmetics. Although drinking water is a negligible source for aluminium, it adds to the woes if the water source is contaminated. Moreover, irrigation facilities close to bauxite ores can significantly contribute to higher levels of aluminium which in turn get absorbed by the crops and enter the food chain.
Many countries are waking up to the growing dangers and passing regulations to control the amount of aluminium in food. A broad regulatory value is 0.6mg/kg of food per week, with an overall tolerable limit of 2mg per kilo of body weight. Excesses lead to perils and awareness goes a long way in minimising the hazards. Reading labels provides a safety net while switching to use of glass and steel for storage could contain the exposure.
(The writer is a science communicator, journalist and writer)