Is Aluminum Zirconium Tetrachlorohydrex Gly safe on skin (left on)?

Aluminum zirconium tetrachlorohydrex gly is an FDA-approved active ingredient for OTC antiperspirants in the US, allowed up to 20% concentration, and requires a mandatory warning for individuals with kidney disease; in the EU, it is covered by Annex III of the EC Cosmetics Regulation with specific conditions of use, including concentration limits (e.g., up to 20% in non-spray products and 10% in spray products) and warnings against use on broken or irritated skin.

Why here

This ingredient is specifically regulated for its intended use as a dermal leave-on antiperspirant active, necessitating adherence to concentration limits and specific labeling requirements to ensure consumer safety.

What would have to be true

Use in antiperspirant products at concentrations up to 20% (US, EU non-spray) or 10% (EU spray) applied topically to the underarms.

The other side

N/A.

Aluminum zirconium tetrachlorohydrex gly can potentially cause skin irritation, especially in individuals with pre-existing skin conditions, or when applied to broken or recently shaved skin, and can trigger an immune response in sensitive persons.

Why here

As a dermal leave-on product, antiperspirants containing this ingredient are applied directly to the skin, often in the sensitive underarm area, where irritation, allergic reactions, or contact dermatitis can occur, particularly if the skin barrier is compromised.

What would have to be true

Direct topical application to the skin, especially on sensitive, broken, or recently shaved skin.

The other side

While irritation can occur in sensitive individuals, Aluminum Zirconium Tetrachlorohydrex Gly is generally considered safe for most people when used as directed.

Some studies suggest a possible association between aluminum compounds in antiperspirants and breast cancer, particularly with frequent use starting at a young age or when applied to shaved skin, with higher aluminum levels observed in breast tumors than in healthy tissue.

Why here

Dermal leave-on application of antiperspirants to the underarm area, which is in close proximity to breast tissue, raises concerns about potential local accumulation and effects.

What would have to be true

Regular, long-term application of antiperspirants containing aluminum compounds to the underarm, especially on shaved or irritated skin.

The other side

Major health organizations, including the American Cancer Society, National Cancer Institute, FDA, and WHO, state there is no conclusive scientific evidence linking antiperspirants or aluminum to breast cancer risk. Studies indicate very low dermal absorption of aluminum from antiperspirants (estimated at less than 0.01%), and no meaningful difference in aluminum levels between cancerous and healthy breast tissue has been consistently shown.

In vitro studies suggest that aluminum, including related aluminum salts like aluminum chlorohydrate, may act as a metalloestrogen, potentially interfering with estrogen receptor signaling, increasing estrogen receptor alpha protein levels, and affecting hormonal balance.

Why here

Dermal leave-on application allows for potential absorption into the body, where aluminum could interact with biological systems as suggested by in vitro research.

What would have to be true

Dermal exposure to aluminum compounds in antiperspirants.

The other side

The Scientific Committee on Consumer Safety (SCCS) considers that systemic exposure to aluminum via daily applications of cosmetic products does not significantly add to the systemic body burden of aluminum from other sources, and there is no safety concern for consumers even when considering total exposure from all known sources.