There has long been concern that the aluminium in antiperspirants could be linked to breast cancer which had seemingly been started by an email rumour.
An article published by the American Cancer Society discusses the issue in detail and concludes that the claims are untrue. It cites a well conducted case-control study undertaken in the US that there was no evidence to link the use of aluminium containing antiperspirants with an increased risk of breast cancer. A case control study is the best method to look for risk factors. A group of 813 patients with the disease in question (the cases) was compared with a similar sized group of 793 people without the condition (the controls). Each group is then questioned in detail about their exposure to risk factors throughout their lifetime. In this study the odds ratio for developing breast cancer for those who had ever used antiperspirants was 0.9 meaning there was no association.
It should also be remembered that lipsticks, toothpaste and some pharmaceuticals (ant acids and vaccines) contain aluminium compounds as do some food colourings and flame retardants of children’s toys. Since aluminium is poorly absorbed through the skin, the EU Scientific Committee on safety concluded that daily applications of cosmetic products (including antiperspirants) does not add significantly to the amount of aluminium entering the body from other sources most notably the diet.