Ammonium Lauryl Sulfate

Ammonium lauryl sulfate, like any other surfactant, makes a good base for cleansers because of the way it disrupts the hydrogen bonding in water. Hydrogen bonding is the primary contributor to the high surface tension of water. In solution, the lauryl sulfate molecules ionize, meaning that the ammonium or sodium separates from the rest of the molecule as a cation. The rest of the molecule aligns itself with others like it and forms what is known as a micelle. The molecules align themselves in a sphere, with the polar heads (the sulfate) on the surface of the sphere and the polar hydrophopic tails pointing inwards towards the center. The water molecules around the micelle arrange themselves around the polar heads, but this disrupts their hydrogen bonding with the water surrounding them. The overall effect of having these micelles in an aqueous (water) environment is that the water becomes more able to penetrate things like cloth fibers or hair, and also becomes more readily available to solvate anything coming off the before mentioned substance.

In high concentrations this molecule may cause severe irritation to eyes and skin. Inhalation may cause irritation to the respiratory system. Ingestion may cause irritation, nausea or diarrhea.

In a 1983 report by the Cosmetic Ingredient Review, shampoos containing up to 31% ALS registered 6 health complaints out of 6.8 million units sold. These complaints included two of scalp itch, two allergic reactions, one hair damage and one complaint of eye irritation.

The CIR report concluded that both Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate “appear to be safe in formulations designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin. In products intended for prolonged use, concentrations should not exceed 1%.”

The Human and Environmental Risk Assessment (HERA) project performed a thorough investigation of all alkyl sulfates, as such the results they found apply directly to ALS. Most alkyl sulfates exhibit low acute oral toxicity, no toxicity through exposure to the skin, concentration dependent skin irritation, and concentration dependent eye-irritation. They do not sensitize the skin and did not appear to be carcinogenic in a two year study on rats. The report found that longer carbon chains (16-18) were less irritating to the skin than chains of 12-15 carbons in length. In addition, concentrations below 1% were essentially non-irritating while concentrations greater than 10% produced moderate to strong irritation of the skin.