Is Alum Safe? Uses and Health Concerns

Is Alum Safe? Uses and Health Concerns

By Anne Marie Helmenstine, Ph.D.

Updated February 04, 2020

Alum is an ingredient in some foods and quite a few non-edible products. If you're careful about reading labels, you may wonder what alum is and whether it's really safe. The answer is yes—usually—but in small amounts.

Alum Safety Depends on Multiple Factors

Any form of aluminum sulfate could be called "alum," including toxic versions of the chemical. However, the type of alum you find used for pickling and in deodorant is potassium alum, KAl(SO4)2·12H2O. Sodium aluminum sulfate is a type of alum that is used in commercial baking powder.

Potassium alum has been used in maraschino cherries and pickles. The aluminum helps make the cell walls of fruits and vegetables sturdier, producing a crisp pickle or firm cherry. Although alum is approved as a food additive by the U.S. Food and Drug Administration, it is toxic in large doses. The current trend is to reduce reliance on chemicals to improve food texture. Alum may be used to soak some pickles, but it is no longer used in the final pickling solution.

Alum in deodorant may be absorbed through the skin into the bloodstream. Although it is deemed safe enough for this purpose by the Food and Drug Administration, there may be negative health consequences from continued exposure to aluminum ions in the alum. Because some of the product is absorbed into the skin, one way to cut your exposure to the product is to apply it every other day, rather than every day.

Alum is the key ingredient used in styptic powder and pencils. The small amount absorbed into the bloodstream from occasional use shouldn't cause health problems.

Women are advised against using alum to tighten the vaginal wall. While the astringent property of the mineral may temporarily tighten tissue, use of the mineral in this manner may result in scarring, increased susceptibility to infection, and absorption of toxic chemicals.

Alum Health Concerns

All forms of alum can cause irritation of the skin and mucous membranes. Breathing alum can cause lung damage. Aluminum also may attack lung tissue. Because it's a salt, eating massive amounts of alum can make you sick. Usually ingesting alum will make you vomit, but if you could keep it down, the alum could upset the ionic equilibrium in your bloodstream, just like overdosing on any other electrolyte.

However, the primary concern with alum is long-term exposure to low levels of the chemical. Aluminum, from your diet or healthcare product, can cause degeneration of nervous system tissue. It has been suggested that long-term exposure to aluminum could lead to an increased risk of certain cancers, brain plaques, or Alzheimer's Disease, but there is currently no evidence to support this claim.

Alum from natural sources may contain impurities, including toxic metals such as chromium. Because the chemical composition of natural alum is variable, it's best to avoid its use when there is a chance of ingesting the mineral or getting it into the bloodstream.

Alum Material Data Safety Sheets

If you are concerned about the specific risks associated with alum, it's best to consult a Material Data Safety Sheet. You can search for these online and find them by a specific type of alum, like potassium alum.