SLS (sodium lauryl ether sulphate, also known as sodium dodecyl sulphate SDE) is a common ingredient in shampoos, toothpates, shaving creams and gels, hand soaps, liquid soap and washing detergents. It is included for its foaming, thickening and penetrating properties. It has a harsh, drying effect on the skin. In toothpastes it can slow the healing, and cause recurrence of, apthous ulcers and desensitises perception of sweet taste. It is also often derived from unsustainable palm monocultures.