Acetamide MEA is a common additive in hair products. Questions about whether it’s toxic or carcinogenic have been thrown around the Internet. But before jumping to conclusions based on the fact that it’s on a list, it’s important to look at the studies and facts and understand whether or not it’s actually dangerous.
What is it and what does it do?
Acetamide MEA is an ethanolamine used most commonly in hair products as a conditioning agent and thickener. It’s a combination of acetic acid and ethanolamine – hence its name, acetamide. It serves as a foam-booster in shampoos and soaps.
As of 2008, it was used in at least 148 formulas. It’s also a humectant — which means it takes in water from the outside — because of the crystals in it (International Journal of Toxicology, A Consumer Dictionary of Cosmetic Ingredients).
Is it irritating in cosmetics?
Acetamide MEA in topical products is considered, at most, a mild irritant. Several studies on rabbits have shown that acetamide MEA was mildly irritating and not sensitizing after prolonged application (13-week study) or a high concentration (70% occlusive patch for 24-hours) (Cosmetic Ingredient Review).
As for human exposures, in a study with 19 women, a 0.5% solution was found not to cause unacceptable amounts of clinical irritation. Another study with 50 subjects using 7.5% found that it did not cause primary irritation or sensitization.
Overall, the FDA deems it as safe in typical beauty product concentrations, but permits no more than 7.5% in leave-on products and no more than 20% in washout products. Acetamide MEA should also never be in a formula including nitrosating agents, as they could form nitrosamides, which have been associated with cancer development.
What about Spray Products?
In certain spray products, like deodorant, most droplet diameters aren’t respirable, though some can be (American Cyanide Company). Acetamide MEA can cause respiratory ailments for people with constant exposure, like hairdressers, which one study found (Chest). However, please note this was a test with ethanolamine, which is stronger than acetamide MEA.
Is it carcinogenic?
Acetamide MEA has been suspected to be a carcinogen with large-scale exposure, but there’s no data that this is a problem in topical application, as with hair products (Carcinogens Reference List). None of the studies done when it’s put on skin demonstrated toxicity or carcinogenesis.
As for food, that’s a different story. The Joint Expert Committee on Food found acetamide MEA to be unacceptable as an additive to food coloring. They also initially deemed acetamide MEA to be a carcinogen upon ingestion based on studies with mice and rats, but later ruled out gene toxicity as the cause (A Consumer Dictionary of Cosmetic Ingredients). In later studies, acetamide MEA was found to be non-mutagenic (non-mutation-causing) in rat hepatocytes (liver cells).
Bottom Line
Acetamide MEA is generally considered safe in beauty products. It’s only mildly irritating, and with low toxicity. In concentrations of 7.5% in leave-in products and 20% in washout products, it is safe to use.
However, consuming or aspirating it has been shown to cause illness and cancer in studies, so in that regards it can be a carcinogen. As with many ingredients, it requires more investigation to be 100% certain. We recommend keeping an eye out for new studies, but it appears to be fine in cosmetic products (just be careful with spray deodorant)!
