Science arises from contradiction. Authors battle themselves using evidence as a weapon in order to achieve the so rare “scientific consensus”. From this organized mess we have been able to provide some answers to important matters in the past. To answer the question of whether aluminum in antiperspirants can cause breast cancer, we need to dig deep into one of these debates.
Three studies came up with the link between cancer and antiperspirants with aluminum.
The first evidence of such a link comes from a 2001 article that found that breast tumors appeared mostly in the upper outer quadrant of the breast. Then in 2003, a study claimed that antiperspirant/deodorant use and underarm shaving were associated with an earlier age of breast cancer diagnosis. Finally, a 2005 article reported a significant and linear increase in breast cancer located in the upper outer quadrant over the period 1979– 2000, an area closer to the armpit and presumably more exposed to aluminum deposits from cosmetic use. These publications created a hypothesis that the aluminum contained in antiperspirants causes breast cancer.
There isn’t strong evidence to support that antiperspirants with aluminum cause cancer.
As a consequence, several studies have been conducted to determine whether there is a link between aluminum-containing antiperspirants and breast cancer. Most of the epidemiologic studies conducted to date have not produced consistent results on this association. There are mixed results, but no article with high quality evidence proving the correlation. The claim that the incidence in the upper outer quadrant increases over time has not been confirmed. Other evidences suggests that there is no association, such as the non-increase in the incidence of bilateral breast cancer. If the product is applied to both armpits, it should increase the incidence of bilateral breast cancer, but this was not the case. In addition, men also use these products, so we should find an increased incidence of breast cancer among them. But we didn’t.
Although there is some biological evidence that aluminum has some carcinogenic potential when tested in vitro and in animal models, the human body is far more complex than these tests can capture. This evidence isn't strong enough.
What do the American Cancer Society and the National Cancer Institute say?
In the meantime, the American Cancer Society has stated: “There are no conclusive epidemiologic studies (studies in humans) linking breast cancer risk to antiperspirant use, and very little scientific evidence to support this claim”. The National Institutes of Cancer say: “no scientific evidence links the use of these products to the development of breast cancer”.
Our recommendation regarding aluminum in antiperspirants
So, the conclusion is not categorical: aluminum probably does not cause breast cancer. This might not be the answer that you were expecting but it’s what science is saying far. Since it is still a subject in debate, if you want to be extra careful it is prudent to reduce exposure to aluminum and avoid application on injured or irritated skin.
Written By Luis Guilherme