Sometimes the cosmetics industry is one filled with oxymoronic contradictions. Take, for example, the use of cationic surfactants, positively charged chemicals based on quaternary ammonium cations.

Cationic surfactants are used for hair conditioner, mouthwash, and soap, among many other things. However, in the long run, they make your hair dry and brittle, irritating hair follicles; short-term, “oral intake of them can be fatal”; and irritate the skin as well. Sisyphean indeed. It only gets better (or worse?): the same chemicals that go in your conditioner, your mouthwash, and your soap are also used in germicide, fabric softener, and detergent. Comfort yourself with the thought that you are cleaning your mouth with detergents!

Many chemicals fall into the category of cationic surfactant. Stearalkonium chloride (SKC), benzalkonium chloride (BZK), cetalkonium chloride (CKC), cetrimonium chloride (CTC), cetyl pyridinium chloride (CPC), glycidyl trimethylammonium chloride, distearyldimonium chloride, lauryl dimonium hydrolyzed collagen, polyethoxylated tallow amine (POEA), cetyl trimethylammonium bromide (CTAB), and many more – these are all elements in this particular set, conveniently allowing for more diversification of adverse side effects as well as a way to hide the presence of cationic surfactants from unwary customers.

For example, a group of scientists from Shimane and Hiroshima universities in Japan discovered that rats injected with BZK accumulated deposits of it in their lungs and kidneys, before dying from the toxic effects. In humans, exposure to this corrosive chemical can induce paralysis; lowered blood pressure; CNS depression; weakness, loss of consciousness; skin, eye, nose, throat, and mucous membrane irritation; and inhibit breathing. CTAB and CPC’s harmful consequences can take place by practically all methods: ingestion, inhalation, and exposure to skin; CPC is even more toxic if inhaled.

Cosmetics companies, of course, do not advertise this information. One ingredient explanation for SKC went thus: “Stearalkonium chloride is a conditioner that binds to the hair to leave it feeling soft and silky. It also enables the hair to be styled with more control, and reduces fly-away produced by static.” Note the absence of anything relating to its long-term effects or allergenic properties.

It is hard to avoid cationic surfactants. A quick survey of the ingredient labels on the cosmetics in my own house turned up kids’ hair spray with CTC, toothpaste with CPC, moisturizing lotion with distearyldimonium chloride, and sunblock with hydrolyzed collagen. The best that you can do is to scrutinize each cosmetic item, be it lotion or shampoo, for surfactant ingredients, and choose your mouthwash wisely.

ThinkQuest 2006: Xiaoxiao, Lisa, Susan & Sri