Children's toys are often criticised, health investigators repeatedly find substances of concern in plastic bottles and sweaters as well. For several years now another group of products has been working up tempers too: deodorants. One group of active substances in particular is subject to discussion.

Many deodorants contain aluminium salts such as aluminium chlorohydrate. These pull the skin together and clog sweat pores like a cork. In this way they ensure that one sweats less.

For the cosmetics industry, these materials are an asset. For some time however, the rumour has been going around that aluminium is supposed to increase the risk of breast cancer and power the development of Alzheimer disease. Only recently a film on French-German TV channel ARTE unsettled many consumers. The audience got to know a cancer patient who suspected the existence of a link between her illness and deodorant use. The scientist and oncologist Philippa Darbre expressed her views on this. She claims to have found that aluminium transforms healthy breast cells in Petri dishes into cancer cells.

Aluminium-containing deodorants in any supermarket. A scandal?

It’s not quite so simple. If one looks at the film more closely, it becomes clear that fears are provoked here without providing real facts. High doses of aluminium act as a poison, which can cause the body serious harm. But what occurs with small amounts such as those found in deodorants? In fact, no one can tell thus far whether the aluminium contained increases the risk of breast cancer or Alzheimer’s disease. The available studies show inconsistency and most studies do not meet the required academic standards. It is true that scientists in recent years have noted an increased development of tumours in the upper-outer quadrant, that part of the chest which is particularly close to the armpits. Beyond that the influence of aluminium was studied.

Among other things, a piece of work was published according to which higher aluminium concentrations were able to be detected in the liquid of the nipples of breast cancer patients than in healthy subjects. Other studies however showed no noticeable differences between the aluminium contents in healthy and diseased breast tissue. But even if aluminium should accumulate in cancer cells, this does not yet mean that the substance is also the cause responsible for the disease. The aluminium might also accumulate as a result of changes in the tissue.

Do not apply to freshly shaved skin

In order to provide a better overview, the Scientific Committee of the European Commission for Consumer Safety is grappling with the topic. The experts looked once again at all previous studies. They weren’t able to recognise any acute danger: “The SCCS is of the opinion that the available information does not support the concerns about a possible cancer-promoting effect of aluminium”, it states in the provisional opinion statement, which was able to be commented on until May 26. Nevertheless, experts advise that aluminium-containing deodorants at least not be applied to freshly shaved skin. From outside, the metal compounds can indeed only with difficulty find their way into the body. Experts assume that a few milligrams of aluminium are applied with a deodorant, but of this probably only tiny amounts in the microgram range manage to reach the bloodstream. The sharp blades of a razor, however, lead to micro-injuries to the skin. Through these far more aluminium can be absorbed than through intact skin.

In addition, aluminium does not only exist in deodorants. As the third most abundant element in the earth’s crust, aluminium is a natural component of human plant-based nourishment. It occurs in foods such as tea, cocoa, chocolate, lettuce and vegetables. As a dye component it is mixed in industrial sugar-based and bakery products, or cosmetics such as lipstick and eye-shadow. It is to be found even in toothpastes or sunscreens, small amounts of the metal are transmitted from fine metal coverings and films to the food. In this way too much of the metal may be managing to enter the body. “The tolerable upper intake level is probably reached solely via food for a part of the population”, says the German Federal Institute for Risk Research, the BfR. Add to this the burden of aluminium-containing deodorants, the limit could at least sometimes get exceeded and aluminium thus accumulate, for example, in the lungs, skeletal system or brain.

Studies with consistent body of data needed

Nevertheless, there is also repeated reporting of a risk for Alzheimer’s. Researchers have found the metal – among many other substances – in the amyloid plaques of diseased brains. But it is involved in their creation? The experts of the SCCS play down the issue on the basis of a lack of unequivocal results. A similar conclusion was previously reached by the German Federal Institute of Risk Assessment. In February this year they wrote in an opinion piece: “Several epidemiological studies that attempt to prove a relationship between the intake of aluminium (…) and Alzheimer’s disease do not permit any scientific deduction because of the inconsistent nature of the data”. The consumer policy spokesperson of the German Greens, Nicole Maisch, has now urged the government to better guarantee the safety of cosmetics: “Consumers need to be informed about possible health dangers”. The German federal government wants to deal with the issue. Upon a request from the Green Group in the Bundestag the German Federal Ministry of Consumer Protection replied that the measures needed would be discussed. What’s more, an additional labelling system for the cosmetics involved would be tested out.

What is needed now are good studies that will work out – free from conflicts of interest – whether or not and how aluminium present in cosmetic products can harm health. Scientists need to find out what the reasonable limits for the various aluminium compounds are and how consumers can avoid an increased intake. Whoever would like to do without deodorants with aluminium already has a large selection available. A look at the ingredients is enough. Some manufacturers already advertise on their packaging the fact that their product does not include aluminium.