Sorbitan stearate is an essential ingredient in many lotions and other skin-care products. It acts as a humectant to bind moisture, thicken the product, and stabilize the mixture of water and oils. This stabilization effect is why sorbitan stearate is known as an emulsifier — it allows two liquids, which normally would not blend, to form a stable mix called an emulsion. Many everyday products use this to keep a cream base from breaking apart during long-term storage in vials, jars, and bottles. Separation may still occur, however, when products are subjected to extreme hot or cold temperatures.
The source of sorbitan stearate is berries and other vegetable matter. The compound is derived as a natural alcohol, combining a sugar alcohol called sorbitol with fatty acids from vegetables. Sorbitol can be found in natural sources such as corn, plums, and many other common foods. When the sorbitol and fatty acids react, they create a new compound that retains the humectifying properties of sorbitol, and makes the alcohol an effective skin moisturizer and softener. This is why it is often used in anti-aging formulas, rash treatment creams, and dry skin treatments. The moisturizing properties are also useful in sunscreen lotions and creams.
The compound is also used in some cosmetics. Sorbitan stearate can act as a binding agent for cream-based cosmetics, such as cream eyeshadow or liquid foundation. It can also act as a moisturizing agent to reduce the dehydrating effects caused by repeated use of some cosmetics, and to reduce skin flaking caused by wearing makeup over long periods of time. Lotion-based medical treatments and salves, such as athlete's foot medications, may also include some form of sorbitol-based emulsifier.
Sorbitan stearate has a low risk of allergic reaction and is generally considered a gentle substance, safe for topical use. Some users have reported skin reactions, including irritation, redness, and hives. These reactions are usually mild, rare, and treatable by conventional methods. Many baby products use the compound, and little to no adverse effect has been reported on infant skin.
The Environment Canada Domestic Substance List has raised concerns about sorbitan stearate as a possible environmental toxin. Many cosmetic products identify the compound as an environmentally-safe plant emulsifier, however. Other, non-naturally derived stearates may pose issues with water pollution or environmental toxicity — such as glycol stearate, which combines natural stearate alcohols with toxic ethylene glycol to produce sheened, pearl-like textures in products like shampoos.