Is Isononyl Isononanoate Safe?



What Is Isononyl Isononanoate?

Isononyl isononanoate is a synthetic ingredient used in cosmetics and skincare products to improve the texture and feel of a formulation. Isononyl isononanoate is used mainly as an emollient, texture enhancer, and plasticizer.

The esters and salts of nonanoic acid are called nonanoates, hence isononyl isononanoate. The esters of nonanoic acid occur naturally in the oil of pelargonium, a group of flowering plants that include about 200 species of perennials, succulents, and shrubs, commonly known as geraniums. Pelargonium is native to temperate and tropical regions of the world, with many species in southern Africa. 

Nonanoic acid, also known as pelargonic acid, is a fatty acid composed of a nine-carbon chain terminating in a carboxylic acid. It is a clear, oily liquid that is nearly insoluble in water.

Isononyl isononanoate can also be produced by esterification of isononyl alcohol and isononanoic acid. Isononyl isononanoate has unique characteristics including extremely low freeze point, low viscosity, and excellent solubility and compatibility in a variety of ingredients such as esters, volatile silicones, mineral, and vegetable oils. Isononyl isononanoate is typically used at concentrations ranging from 2 to 10%.

Isononyl Isononanoate

the good:Helps to improve the texture and feel of a formulation.

the not so good:Isononyl Isononanoate doesn’t provide the skin with any significant benefits and is mainly used to improve the formulation. 

Who is it for?All skin types except those that have an identified allergy to it. 

Synergetic ingredients:Works well with most ingredients 

Keep an eye on:Nothing to keep an eye on here. 

Why Is Isononyl Isononanoate Used?

In cosmetics and skincare products, isononyl isononanoate functions as an emollient, texture enhancer, and plasticizer.

As an emollient, isononyl isononanoate is often found in creams, lotions, and facial moisturizers. Emollients work to soften and soothe the skin while also acting as occlusive agents. Occlusive ingredients form a protective film on the surface of the skin, which helps to prevent evaporation of the skin’s natural moisture. Over time, this increases skin hydration by causing a buildup of water in the uppermost layer of skin.

These same emollient properties make isononyl isononanoate an ideal ingredient for hair care products. It forms a smooth, even film on the surface of the hair that provides increased slip between adjacent hair strands, which makes detangling easier. Isononyl isononanoate further reduces tangling by smoothing and flattening the cuticle surface, which can also add shine and gloss to the hair. It leaves the hair feeling soft and silky without weighing it down or making it feel greasy.

As a texture enhancer, isononyl isononanoate offers superior spreadability and a dry touch feel. It gives skincare products a distinctive velvety feel. Furthermore, isononyl isononanoate acts as a replacement for volatile silicones in antiperspirants where it reduces tackiness and prevents clogging in aerosols.

Lastly, isononyl isononanoate functions as a plasticizer. Plasticizers are materials that soften synthetic ingredients by reducing brittleness and cracking. Plasticizers are useful for cosmetic products such as nail polishes, glosses, and shampoos.

Is Isononyl Isononanoate?

The United States Food and Drug Administration (FDA) includes nonanoic acid on the list of food additives permitted for direct addition to food for human consumption.

The safety of nonanoic acid and its esters, including isononyl isononanoate, has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel, a group responsible for evaluating the safety of skincare and cosmetic ingredients. The Expert Panel reviewed data that indicated that nonanoic acid is not toxic. At concentrations of 12% and less, nonanoic acid is not a skin irritant. Furthermore, since nonanoic acid does not readily penetrate the skin, it is not a sensitizer. After evaluating the scientific data, the Expert Panel concluded that these ingredients were safe for use in cosmetics and personal care products.

The Expert Panel noted that nonanoic acid and its esters may increase the dermal penetration of other ingredients. The Expert Panel cautioned that care should be taken in formulating cosmetic products that contain these ingredients in combination with other ingredients for which dermal absorption was a concern.

References:Johnson, W, 2012. ‘Final Report of the Cosmetic Ingredient Review Expert Panel on the Safety Assessment of Pelargonic Acid (Nonanoic Acid) and Nonanoate Esters’, International Journal of Toxicology.


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