There are concerns about the health effects of exposure to aluminum, including the aluminum salts found in most antiperspirants. Aluminum is not classified as a human carcinogen. The Aluminum Association states "there is no evidence that normal day-to-day use of aluminum products - whether in food, cookware, drinking water, deodorant, medicines or cosmetics - causes any adverse health effects."
However, aluminum workers are at heightened risk for neurologic disorders, indicating that there is a level of exposure at which aluminum is a powerful neurotoxin. Aluminum also appears to be a breast carcinogen. The question for breast cancer survivors and those at high risk is whether routine daily use of aluminum-containing antiperspirants contributes to breast cancer risk.
Now a new study has reported that aluminum salts can damage DNA and compromise the functioning of tumor suppressor genes (including BRCA1 and BRCA2) in normal breast cells.

Aluminum and breast cancer

Most antiperspirant sprays, sticks, and roll-ons contain aluminum chlorohydrate or another aluminum salt to block the secretion of sweat. The aluminum in such preparations has been shown to enter through the skin in tiny amounts and accumulate in all types of breast tissue, including in the upper outer quadrant where many tumors arise.
Aluminum has been shown to cause oxidative damage to cellular components and to induce inflammatory responses within the breast. The presence of aluminum also appears to alter iron metabolism in breast tissue, increasing iron levels, with unclear consequences. Several studies have shown that aluminum can induce DNA damage at concentrations typically found in human breast tissue. Aluminum has also been shown to interfere with the functioning of estrogen receptors of estrogen positive (ER+) breast cancer cells.
Aluminum could also promote metastasis. One study demonstrated that the presence of aluminum increased both the migratory (ability to move freely and distance moved) and invasive properties of hormone receptor positive (ER+/PR+) breast cancer cells. In the study, this effect was seen after long-term (32-week) exposure - short-term (one week) exposure had no effect. Another study reported similar effects of aluminum in triple negative (ER-/PR-/HER2-) breast cancer cells.

Breast cancer survivors and antiperspirants

Antiperspirants containing aluminum salts are generally more effective in reducing sweat than products without aluminum. However, it would be worth trying one or more of the available aluminum-free products, which might be adequate for many women, especially as they age.
As noted above, aluminum in antiperspirants has been shown to enter into circulation through the skin. The amounts are generally tiny, with the highest exposures generated by spray antiperspirants, followed by sticks, then roll-ons. Applying an antiperspirant to skin that is scraped, cut or irritated (such as may occur after shaving) can result in far higher exposures. The implication is that it is better to use roll-on or gel antiperspirants than sprays or solids. In addition, such products should not be applied right after shaving or if the underarm skin is broken or shows signs of irritation. It also makes sense to apply as little as necessary and not to apply antiperspirants more than once per day.
Given the increase in inflammation induced by aluminum, inflammatory breast cancer (IBC) patients should probably entirely avoid using aluminum-containing antiperspirants and deodorants. Based on the results of the study described below, BRCA1 and BRCA2 mutation carriers are also best off avoiding such products, even after mastectomy.

Latest research finds aluminum can damage DNA and compromise DNA repair

The study referenced at the beginning of this news story was designed to investigate the effects in non-cancerous breast cells of exposure to aluminum salts commonly used in antiperspirants. To conduct the study, the authors used MCF-10A immortalized non-transformed human breast epithelial cells. Both aluminum chlorohydrate and aluminum chloride were found to interfere with DNA repair systems in MCF-10A cells. Long-term (defined as 19 to 21 weeks) exposure to aluminum chlorohydrate and aluminum chloride caused lowered levels of BRCA1 mRNA and BRCA1 protein. BRCA1 (breast cancer susceptibility gene-1) is a tumor suppressor gene. Mutations in BRCA1 and other tumor suppressor genes can cause carriers to have relatively high lifetime risks of developing breast and other cancers. Reduced levels of mRNA for other DNA repair genes (including BRCA2, CHK1, CHK2, Rad51, and ATR) were also observed.
As noted above, loss of BRCA1 or BRCA2 gene function is associated with increased susceptibility to breast cancer. Harmful BRCA mutations have a strong heredity component. However, the study results suggest that exposure to aluminum-based salts in antiperspirants can also reduce levels of these vital components of DNA repair in breast cells. The authors conclude that aluminum has the potential to influence breast carcinogenesis since aluminum can not only damage DNA but also compromise DNA repair systems.
Please see our personal care products tag for more information concerning consumer products that could influence breast cancer risk or survival.