A Quick and Dirty Guide to Sulfates in Hair Care

Unless you have been under a rock, I am sure that you have noticed an explosion in the number of sulfate-free cleansers that have entered the product market. Those with curlier textures have been steered away from the use of these agents giving preference to texture friendly co-washes and sulfate-free shampoos. Why is this the case? What is the problem with sulfates and sulfate-based cleansers? Here is a quick and dirty guide to sulfates and all that you need to know to determine if they will be part of your natural hair journey.

What are sulfates?

Chemically, a sulfate is composed of a sulfur atom surrounded by four oxygen atoms and has a chemical formula of SO4(2−). Sulfates are commonly used primary surfactants in shampoo formulations and other cosmetic cleansers. Surfactants attract both oil and water and help to suspend particles (i.e. sebum, debris, oil) in water to be rinsed away. They are largely responsible for the foaming action of soaps, shampoos, and other detergents. The most widely used surfactants include sodium lauryl sulfate, sodium lauryl ether sulfate, ammonium lauryl sulfate, and ammonium lauryl ether sulfate due to their high efficacy, ease of use and compatibility, and low cost.

Chemical structure for sodium lauryl sulfate (SLS)

What is the concern with using sulfate-based cleansers?

Sulfates have an excellent safety record and are very effective cleansers. So much so that they often remove even the natural oils from the skin which are necessary to maintain skin integrity and moisture. This can be very drying to the skin, hair, and scalp and lead to irritation and a cycle of overproduction of natural oils that can result in acne and blemishes. Furthermore, the compounds themselves can be irritating to the eyes, skin, and mouth.

Despite the fact that no evidence has linked sulfates themselves to cancer and other health issues, safety concerns have been expressed regarding trace amounts of 1,4-dioxane found in some sulfate-based products. This is a potential contaminant and possible carcinogen that can arise as a byproduct of the ethoxylation process which is used to modify sodium lauryl sulfate to the gentler sodium lauryl ether sulfate. Since cosmetic regulation in the US does not require product testing, the degree to which this compound is found in the hair care industry is unknown.

There is an environmental impact of sulfates that should also be considered. Use and disposal of these compounds into the environment from household water systems have been reviewed and it has been found that a surfactant concentration of 0.5 mg/L of natural water would be essentially nontoxic to fish and other aquatic life under most conditions. One of the greater concerns is actually how sodium lauryl sulfate is made. Sodium lauryl sulfate can be made from two sources – petroleum oil (nonrenewable) or coconut or palm oil (renewable). The use of plant-derived sodium lauryl sulfate avoids unnecessary risk to the environment through the use of a nonrenewable resource for production.

What should I know about sulfate-free shampoos?

Much of the concern surrounding the use of sulfate-based cleansers is the significant drying effect that can occur with use. Stripping away natural oils from the hair and scalp can lead to dry, brittle hair that is prone to breakage. Moisture is key to the health of curly and highly textured hair so this drying effect is not a desired result and must be counteracted with use of a conditioning treatment to restore oil and moisture lost during the shampoo process.

Some companies have shifted to the use of milder detergents such as sodium coco-sulfate which is derived from coconut oil, however, this is still technically a sulfate. It has a molecular size which reduces the amount of skin irritation because it cannot easily penetrate the outer layers of skin and is a palm-free option that avoids the environmental concerns associated with other sulfate cleansers. This is one example of how product labeling can be misleading in that “sulfate-free” often refers to the absence of sodium lauryl sulfate and sodium lauryl ether sulfate rather than the absence of an actual sulfate molecule.

Shampoo products that are completely sulfate-free are formulated with surfactants such as cocoamidopropyl betaine and avoid the use of a primary anionic surfactant. Many of these alternatives have a better dermatologic profile (less irritating) but do not always remove chemical debris deposited on the hair. Over time this can potentially lead to problematic build up on the hair strand requiring the use of a clarifier for removal.

The bottom line…

Sulfates are highly effective detergents to remove debris, grease, and build up from the hair. They can be overly drying and have the potential to cause skin irritation. Complete avoidance of sulfates may be desired by some, however, many concerns can be addressed through proper formula development. Sulfate-based product options are available that mitigate some of the negative impacts these agents may have on the hair and scalp. The key is figuring out what you desire for your healthy natural hair journey.

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