A study by Flarend et al, published in the journal Food and Chemical Toxicology, found that a one-time use of aluminum chlorohydrate, found in many antiperspirants, applied to the skin is not a significant contribution to the body burden of aluminium.

However, another study, by Farasani and Darbre ,published in the Journal of Inorganic Biochemistry, found that use of underarm aluminium (Al)-based antiperspirant salts may be a contributory factor in breast cancer development, by damaging DNA and compromising DNA-repair systems.

For more about the confusing data on this subject, see this page on the National Cancer Institute’s website, and this page from breastcancer.org’s website.

The data concerning the impact of aluminum in antiperspirants on breast cancer is muddy and unclear.  On this subject, we advise using the Precautionary Principle–better safe than sorry.