Is Natural Deodorant Healthier For You? Starting With Aluminium

Why is Aluminium used in antiperspirants?

Deodorant and antiperspirant sit side by side on the shelf and get talked about as the same thing. They work in completely different ways, and the difference is this one ingredient.

Antiperspirants contain aluminium salts, usually Aluminium Chlorohydrate or Aluminium Zirconium Tetrachlorohydrex Gly. When they meet moisture on the skin they form a soft plug in the opening of each sweat duct, so sweat can't reach the surface. The plugs sit there for around a day and wash out gradually.

Deodorant leaves the sweat glands alone. Sweat on its own is very close to odourless, and the smell only turns up later, once skin bacteria have started breaking it down. Deodorant works on that second stage instead.

Which means there's a simpler question sitting in front of the safety one: do you want to stop perspiring at all? Sweating is how your body manages its own temperature, and plenty of people decide they'd rather not switch it off every morning.

How much Aluminium gets in?

Most of what you apply stays on the surface and washes away. A small proportion passes through the skin, and that has been measured directly. In 2001, Flarend and colleagues used a radioactive tracer to follow aluminium chlorohydrate through the body after a single application. Around 0.01% of the applied dose was absorbed, roughly four micrograms from one application to both underarms. A more recent microtracer study, published in 2022, put the figure lower again.

Those are small numbers. What they measure is also quite specific: one application, of one product, on intact skin, in a very small number of people. What they don't measure is the same product applied every morning for forty years, on skin that's just been shaved, alongside everything else in the bathroom cabinet.

Skin that's been shaved matters here. Laboratory studies on stripped skin, where the outer barrier has been deliberately removed, found considerably greater penetration, and the researchers recommended caution when applying aluminium salts to compromised skin. Shaving disturbs that same barrier, which is why products sting on freshly shaved skin. Nobody has established a reliable figure for how much normal underarm shaving increases absorption. You'll see one quoted online, but it doesn't appear to trace back to a study.

Then there's what the body does with what it takes in. Aluminium is cleared slowly, mainly by the kidneys, and what isn't cleared is deposited in tissue. It's been measured in bone, lung, liver, kidney, thyroid and brain tissue, and the total body burden tends to climb gradually across a lifetime rather than resetting between applications.

The oestrogen question

This is where most of the concern about underarm products started, and it's worth setting out properly.

Some chemicals can mimic oestrogen in the body. They're known as xenoestrogens, or endocrine disruptors, and they interfere with the hormonal signalling that ordinarily runs on your own oestrogen. Parabens and certain phthalates behave this way. Aluminium salts have also been shown in laboratory studies to bind to oestrogen receptors, which is why some researchers describe them as metalloestrogens.

Lifetime exposure to oestrogen is an established risk factor in breast cancer epidemiology. It's why early menarche, late menopause and long-term HRT all appear in risk models. So anything that adds to that lifetime signal is worth understanding, particularly an exposure that starts in adolescence, while breast tissue is still developing, and carries on for decades.

Aluminium has been detected in the breast across several published studies. Exley and colleagues measured it in breast tissue in 2007, and found concentrations significantly higher in the outer regions of the breast, nearest the armpit, than the inner. Mannello and colleagues measured it in breast cyst fluid in 2009 at a median of 150 µg/l, against around 6 µg/l in blood serum. In 2011 the same group analysed nipple aspirate fluid and found higher levels in samples from women with breast cancer than those without.

What none of that establishes is cause. Darbre's 2011 review, which gathers this evidence together, is explicit about it: aluminium being present in breast tissue doesn't demonstrate that it causes breast disease. The large population studies comparing antiperspirant users with non-users haven't found a difference in breast cancer rates. What the measurements do show is that aluminium is reaching breast tissue, and that researchers are still working out what, if anything, it's doing there.

What "safe" is actually measuring

Regulators work to a threshold. The EU's Scientific Committee on Consumer Safety reviewed the absorption data and set concentration limits for aluminium in cosmetics, and anything sold legally here is formulated within them.

It's worth being clear about what that assessment answers, though. It asks whether a given concentration of one ingredient, in one product, is acceptable on the evidence currently available. It doesn't ask what happens when that ingredient goes on every morning for decades. Or when it goes onto skin that's been shaved minutes earlier. Or when it sits alongside the dozen or so other products most of us use daily, several of which carry their own hormone-active ingredients. Those exposures don't arrive one at a time, but that's very close to how they're studied.

Breast Cancer UK have argued for the removal of aluminium compounds from underarm products altogether, on the basis that this exposure is daily, lifelong, avoidable, and applied right next to tissue that's sensitive to hormonal signalling. When those four things are true at once, waiting for certainty seems like the wrong way round. A limit set for a single ingredient in isolation isn't the same thing as knowing it's safe in the life you actually live.

The rest of the label

Aluminium takes most of the attention, but it's rarely the only thing people find when they turn the packet over.

Individually, none of these is dramatic. It's the pattern that matters. Most of us use around a dozen personal care products a day, and underarm products are among the few that stay on the skin for a full twenty-four hours rather than being rinsed off. Very little of that has been studied in combination, over decades, at the doses people actually use.

Where that leaves the decision

Nobody can hand you a settled answer on aluminium, and any brand telling you otherwise is going further than the evidence does. What can be said is that this particular exposure starts young, repeats daily, lands next to hormone-sensitive tissue, and, unlike almost everything else on the list, sits entirely within your control.

You can't do much about the air on your commute, the water in your tap or what was sprayed on your lunch. You can decide what goes under your arms tomorrow morning.

And the trade is a small one. Deodorant made without aluminium won't stop you sweating, because nothing natural will. What it does is handle the odour, which is what most of us wanted from the product in the first place. Given how easy that swap is, taking it off the list seems a fair thing to do.