Why Are Sulfates in Hair Products Bad?

Sulfates are a common ingredient in lots of cosmetic and cleaning products, including your shampoo and conditioner. While some studies have linked sulfates to cell damage, sulfates are considered safe in concentrations below 1 percent or when used for short periods of time, according to the Journal of the American College of Toxicology.

Sulfates help your shampoo loosen the grease and sebum from your hair and scalp. (Image: nd3000/iStock/Getty Images)

What Are Sulfates?

Sulfates are an additive to cleaning products that causes the foaming action commonly associated with soaps. The most common sulfate is sodium lauryl sulfate (SLS), found in most shampoos and conditioners. Used primarily as a foaming agent, a sulfate combines with water to emulsify grease, dispersing it into the water so that it can be washed away. Sulfates also act as a surfactant, a substance that reduces the surface tension of water, helping your shampoo loosen the grease and sebum from your hair and scalp. A shampoo that contains sulfates typically has a concentration of around 15 percent.

Sulfate-free shampoos don't lather like a traditional shampoo. (Image: ori-ori/iStock/Getty Images)

Sulfates and Skin Damage

SLS is a "low hazard," according to the Environmental Working Group's Skin Deep Cosmetics Database, and has been linked to organ toxicity, skin irritation and ecotoxicology (harm to the environment or a specific ecosystem). However, sulfates are considered to be safe in small quantities by the Food and Drug Administration and the Cosmetic Ingredient Review. In a series of tests conducted by the American College of Toxicology, concentrations below 1 percent, or higher concentrations intended for discontinuous usage, were found to pose no significant health risk to humans; in higher concentrations, sulfates did cause cellular damage. At a concentration of 15 percent with prolonged exposure, harmful effects on laboratory rats included skin irritation, depression, labored breathing, diarrhea and even death. The studies noted that damage increased in higher concentrations but was limited in products designed for discontinuous use, such as shampoos.

Sulfates and Cancer Risk

Sulfates have been rumored to be carcinogenic, but this myth is unfounded. In the 1970s, some shampoos used a different compound, ethanolamine lauryl sulfate, which did contain cancer-causing nitrosamines. Today, these compounds are banned from cosmetic products and no longer constitute a threat in your shampoo bottle. The sodium lauryl sulfates in your shampoo have no carcinogenic properties, according to the American College of Toxicology and the Cosmetic Ingredient Review expert panel, which revisited the compound in a safety assessment conducted in 2002.

Sulfate-Free Shampoos

If you have particularly sensitive skin, sulfates may increase your sensitivity, causing irritation. "Though sulfate-based shampoos do effectively clean the hair, they can also strip the hair of essential oils as well as irritate the skin," cosmetic chemist and BeautyStat founder of Ron Robinson told Glamour. If you dye your hair, sulfate-free shampoos can also help maintain your color, which can be stripped by the detergent in a shampoo that contains sulfates. Sulfate-free shampoos don't foam and lather like a traditional shampoo, an aesthetic difference that accounts for the widespread use of sulfates in cleaning products. Rest assured, however, that despite the reduced lather, your sulfate-free shampoo is still doing its job.

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