A salt is a chemical combination of a metal with some other element like chlorine or oxygen. Sodium chloride, table salt, is an example. A solution of sodium chloride in our bodies is necessary for life but even touching pure sodium will result in severe burns.

It’s what is connected to the metal that makes a salt dangerous or safe.

Some salts of aluminum, zinc, and magnesium kill animals. Zinc, magnesium, and aluminum phosphide is one such salt. Other salts like zinc oxide are safe for humans but kill fish. Aluminum however absorbed may accumulate and become neurotoxic to humans.

Zinc Salts

A chemical called Zinc ricinoleate is used in some deodorants because it effectively absorbs bad odors.

The GHS (Globally Harmonized System) of Classification and Labeling of Chemicals is an international agreement on how to display the properties and hazards of chemicals.

What is the classification for zinc ricinoleate? You may have already guessed it, or you clicked on the PubChem link above – it’s an irritant.

How about zinc oxide? It is commonly applied to skin as sun screen and is extremely well tolerated in humans.

But the GHS hazard warning says it hurts aquatic life in an aquatic environment. It also non-selectively ruptures cell walls in some bacteria.

Magnesium Salts

Magnesium oxide (aka magnesia) is an ingredient in deodorants that frequently advertise that they are aluminum free and baking soda free. Although classified as an irritant and environmental hazard, magnesium oxide is frequently used in small doses as a mineral supplement in capsule or pill form. In water, it forms magnesium hydroxide, sometimes used as a laxative and antacid in appropriate doses.

When magnesium oxide is put on moist skin, it becomes magnesium hydroxide and increases the alkalinity of the skin. The natural acid environment of the skin that harbors useful bacteria is disrupted.

Magnesium Hydroxide (aka Brucite) has been shown to exert an antibacterial activity by by making conditions so alkaline that some strains of bacteria die.

The scientific paper published in 2021 by researchers at a South Korean University stated in their summary, “Therefore, it is considered that additional experiments on the biological safety of brucite mixed with substances that are continuously exposed to human skin are necessary.”

Aluminum Salts

There is no known biological function in the human body for aluminum. Everything is absorbed to varying degrees by the skin. And what is absorbed and not eliminated accumulates in the human body. The question remains, “What is the effect on the body after years of accumulating unnecessary aluminum from deodorant/antiperspirants or the diet?”

Aluminum chlorohydrate (ACH) is the common salt included in antiperspirants in concentrations up to 30% in preparations when prescribed by dermatologists. Over the counter products contain less.

According to one study, more aluminum is ingested than is absorbed through the skin. They applied 84 mg. per armpit for 7 days and were able to show only minuscule quantities measured in micro-grams that were absorbed.

Other research also shows similar small absorption. A German study suggests that only 0.01% to 0.06% is absorbed.

Bottom Line

Some salts are safe; others are not. We don’t use salts in deodorme because they wouldn’t serve any purpose and would interfere with our incredibly effective ingredients.