Aluminum-based compounds have been used in antiperspirants since the late 1950s. Although they are effective in reducing perspiration, there has been ongoing debate and concern regarding their safety, particularly in relation to breast cancer and other health issues.
In this article we explore the current understanding of aluminium in deodorants, examining the evidence and health implications from a scientific perspective.
Potential Health Concerns
Breast Cancer Link
Several points have been raised regarding the potential connection between aluminum in antiperspirants and breast cancer:
- Historical Precedence: Aluminum was introduced in commercial antiperspirants around the 1950s, roughly a decade before an increase in breast cancer incidence [2].
- Topological Redistribution: Modern data shows about 85% of breast cancers occur in the external parts of the breast, near the underarm area where antiperspirants are applied. This shift in cancer location could be influenced by antiperspirant use, though this remains speculative [2].
- Skin Permeability: The axilla's skin is particularly thin and permeable, potentially exacerbated by shaving and certain chemicals in antiperspirants that increase skin permeability [2].
- High Concentrations in Products: Aluminum salts in antiperspirants can be quite concentrated (5-10% w/v aluminium concentration) [2].
- Aluminum Levels in Breast Tissue: Studies have detected relatively high levels of aluminum in the mammary gland of women in industrialized countries. These levels are higher than those typically found in serum [2].
- Absorption and Toxicokinetics: Although studies using aluminum isotopes have shown dermal absorption, they do not fully represent the long-term exposure scenario starting from puberty. These studies primarily measured aluminum in urine, not in breast tissue or other organs [2].
Alzheimer's disease link
- Aluminum Deposits in the Brain: Studies have identified aluminum deposits in the brains of Alzheimer’s disease patients. However, it is unclear whether these deposits are a cause or a consequence of the disease.
- Animal Studies: Some animal studies have suggested that high doses of aluminum can cause neurotoxicity and symptoms similar to Alzheimer's. However, these studies often involve aluminum exposures far higher than what humans would typically encounter.
- Epidemiological Studies: Epidemiological research has not consistently demonstrated a clear link between everyday aluminum exposure and Alzheimer's disease. Some studies have found associations, while others have not. The majority of health organizations and Alzheimer's disease research groups currently maintain that there is no definitive evidence that normal everyday exposure to aluminum causes Alzheimer's disease. They acknowledge that while aluminum exposure should be studied further, the existing evidence does not conclusively link aluminum with Alzheimer's.
Aluminium absorption from antiperspirant deodorants
As aluminum could play a negative role in these health issues, a major factor is to identify how much aluminium we absorb from deodorants.
The problem is that it's hard to conclusively answer that: we don't have definitive and complete answers yet. In particular, a challenge is to understand how much of the aluminium applied to the skin is absorbed in the body (and where).
Let's start with identifying a baseline of how much aluminium we get exposed to everyday.
Dietary Sources: the primary source of aluminum is dietary, with an average intake of about 7-9 mg per day for adults in developed countries [1]. This can vary based on diet and cooking methods.
Antiperspirant Deodorant Source: let's now focus on aluminium from deodorants.
- As mentioned above, average concentration in aluminium in most antiperspirant deodorants is 5-10% (some high strength or clinical are 15-20%).
- If we use an aluminium deodorant for 60 days, weighting 40g, at 10% aluminium concentration: daily aluminium exposure = 66.7mg
You might notice how that's almost 10x higher than the exposure we have with food. That's why this could be of concern.
Absorption: thankfully, only a little of the aluminium we expose ourselves to (either oral ingestion or skin application) gets absorbed.
- Dietary Sources: absorption from orally ingested aluminium is estimated at 0.1% [3]. This would mean 0.007-0.009 mg absorbed per day, or 7-9 µg ( microgrammes), are absorbed from food everyday.
- Antiperspirant Deodorant Source: absorption from skin-applied aluminium is estimated at at 0.01% [4].This would mean 0.007 mg absorbed per day, or 7 µg (microgrammes), are absorbed from antiperspirant deodorants everyday.
Safe tolerable daily absorbed dose: the European Food Safety Authority (EFSA) states a maximum safe tolerable dose of 0.143 µg per kg of body weight. For an adult weighing 60 kg, that is 8.6 µg per day [3].
As we can see above, aluminium absorbed from antiperspirant deodorants might be just as much as the one absorbed from dietary sources.
What's worse, together they would bring us around 2x of the safe tolerable daily dose of aluminium.
Nuances and avoiding fear-mongering
As mentioned above, assessing how much of the aluminium applied to the skin is absorbed in the body is complicated. A recent scientific study is proposing a much lower absorption than the 0.01% used above, estimating it 25x lower than that [5]. If that would be the case, the aluminium absorbed from antiperspirant deodorants would be just 4% of the one absorbed from dietary sources.
Beyond that, to reduce aluminium intake one should also look at reducing dietary sources of it. And, additionally, to be mindful about medical drugs as a few of them can be heavy sources of aluminium.
Uncertainty and knowledge gaps about aluminium absorption from antiperspirants
On the other hand, it's also important to be mindful about what we don't know regarding the effect of aluminium in antiperspirants.
The studies mentioned above about aluminium absorption from antiperspirants* are only limited to a 1-time one-off application, studying the effects of that single application in the days and weeks to come. To emphasise this: the antiperspirant deodorant was applied only 1 time! In real life, we apply antiperspirants multiple times (every single day) over the period which was considered by the studies. It's possible that multiple applications might significantly change the results, and for the worse.
And perhaps the most concerning pitfall, current studies have only been limited to systemic (in the whole body: think blood / urines) absorption and weren't able to exclude a much higher local absorption close to the site of application. For example, in the chest / breast and armpit areas. As we read in one study: "a direct measurement of such 'mammary' aluminium from cosmetic use is lacking, studies using a single axillary application [...] failed to provide information on this point, since they measured absorbed [aluminium] in urine [...] but not in the breast or other internal organs" [2].
Conclusion
In summary, despite current scientific evidence does not conclusively prove a direct health risk, research on aluminum absorption from antiperspirants is limited and does not fully capture the long-term, repeated use and potential localised effects on tissues like the breast.
Despite the lack of conclusive support from current scientific evidence (and the importance to avoid fear-mongering), given the uncertainties (and evolving nature of research in this area) a cautious and informed approach to aluminium exposure is advisable.
A sensible approach might be to avoid aluminium exposure from antiperspirant deodorants. Especially if there are available, effective and affordable alternatives.
Our goal at Pure is specifically to provide such a product with our Deodorant stick. It's aluminium-free and it comes in biodegradable plastic-free packaging.
Note: this presents our best understanding and interpretation of the current evidence on aluminium in antiperspirants.
* both the ones reporting "0.01% absorption" as well as the most recent one suggesting 25x less absorption
Sources
[1] World Health Organization (WHO). In their report titled "Aluminium in Drinking-water," part of the WHO Guidelines for Drinking-water Quality, they provide an overview of aluminum exposure from various sources, including diet.
[2] "The postulated innocuity of lifetime exposure to aluminium should be reappraised" by Mandriota and Sappino. Journal: Frontiers in oncology.
[3] "Aluminium-containing antiperspirants contribute to aluminium intake", BfR opinion No. 007/2014, 26 February 2014
[4] "Human exposure to aluminium," published in the journal "Environmental Science: Processes & Impacts" in 2013. By Philippa D. Darbre and J. M. Harvey
[5] "Assessment of dermal absorption of aluminium from a representative antiperspirant formulation using a (26Al) Al microtracer approach: a follow-up study in humans" by Rianne de Ligt et Al, Toxicology Research, 2022, 11, 511–519