Sodium laureth sulfate (SLES)
Detergent and surfactant found in many personal care products (soaps, shampoos, toothpaste etc.). A cheap and very effective foamer.
There is a persistent but unfounded myth that SLES is carcinogenic.
Sometimes listed as Steol-130, 230, 270, 330, 370 or 460; Stepanol; Alkyl Ether Sulfate; Soudium POE(2) Lauryl Ether Sulfate; Soudium Diethylene glycol Lauryl Ether Sulfate; Sodium Lauryl Ether Sulfate.