Sodium laureth sulfate
Sodium laureth sulfate (SLES, also SLS), is a detergent and surfactant found in many personal care products (soaps, shampoos, toothpaste etc.). It is a cheap and very effective foamer.
If SLES is not present sodium dodecyl sulfate (SDS), ammonium lauryl sulfate (ALS) or sodium lauryl sulfate (SLS, cheaper to make) will probably be.
There is a persistent but unfounded myth (usually circulated via e-mail) that SLES is carcinogenic. It does not cause cancer, but it can irritate the skin and cause nausea or diarrhea if ingested.
Sometimes listed as Steol-130, 230, 270, 330, 370 or 460; Stepanol; Alkyl Ether Sulfate; Sodium POE(2) Lauryl Ether Sulfate; Sodium Diethylene glycol Lauryl Ether Sulfate; Sodium Lauryl Ether Sulfate.