Chemicals that mimic the body's natural hormone oestrogen are known to affect a woman's risk of breast cancer.
Evidence is mounting that the aluminium-based compound, which often makes up quarter of the volume of some antiperspirant agents, can break through the skin and that once in the body it could mimic oestrogen. A review just published in the Journal of Applied Toxicology calls for further research to evaluate the potential that this could increase the risk of getting breast cancer.
Over recent years scientists have found that many compounds in the environment mimic or interfere with oestrogen. These compounds are normally complex molecules and are found in many plants, and used in materials like detergents, pesticides and plastics. Now scientists are realising that a variety of simple metal ions, including aluminium and cadmium can also bind to the body's oestrogen-receptors and influence their action.
"Since oestrogen is known to be involved in the development and progression of human breast cancer, any components of the environment that have oestrogenic activity and which can enter the human breast could theoretically influence a woman's risk of breast cancer," says author of the review Dr Philippa Darbre, who works in the School of Biological Sciences, at the University of Reading, UK.
Aluminium salts in antiperspirants are a major source of exposure to aluminium in humans. It is often sprayed into armpits, inadvertently concentrating exposure near to the breast. In addition, it is often applied immediately after shaving, when the skin is likely to be damaged and less able to keep the aluminium out. "It is reasonable to question whether this aluminium could then influence breast cancer," says Darbre.
Her concern is not confined to aluminium. Smoking tobacco introduces cadmium into the body, and research shows that it too can collect in breast tissue. There are indications that this accumulation of cadmium may also be linked to an increased risk of breast cancer, potentially showing one of the reasons why smoking could be linked to this disease.
"Each of these agents on their own may not have a powerful effect, but we need to see what happens when a number of them act together - it could be that this would have a significant effect on diseases like breast cancer," says Darbre.