“Syndets” were originally developed by chemists to eliminate a problem commonly found with soap, namely “scum” formation. Soaps, unlike detergents, react with dissolved minerals in water to form an insoluble precipitate; often seen as the classic bathtub ring. With sodium lauryl sulphate there is no scum problem.
But there is one problem with SLS. It is such an effective detergent that it is too good at removing the protective oils from the skin and that can result in skin irritation. As far as toxicity goes, given that it is even used in toothpaste, it has undergone a battery of toxicity tests and passed with no problem. But the “natural personal care product” industry sees synthetic chemicals as evil, giving traction to “sodium lauryl sulphate-free” products. But just because the term does not appear on the label does not mean the product does not contain the chemical. All you have to do is come up with a different name for SLS. And there are plenty: olefin sulfate, sodium dodecyl sulphate (SDS), dodecyl sodium sulfate; lauryl sodium sulfate, lauryl sulfate sodium salt, sodium n-dodecyl sulfate, sulfuric acid monododecyl ester sodium salt, and sodium dodecane sulfate.
Another way to hide SLS is by listing “sodium coco sulphate” as an ingredient and explaining that it is derived from natural coconut oil. First, a comment about “derived from.” Converting the fats in coconut oil into sodium coco sulphate involves a series of complex chemical reactions so the final product is hardly “natural.” By this sort of logic an automobile could be described as “derived from nature” because every substance of which it is made originates in nature. Iron-containing minerals and petroleum are as natural as you get. Perhaps more significantly, lauric acid makes up about two thirds of the fatty acids of which coconut oil is composed so that when this mixture undergoes the conversion to sulphates, sodium lauryl sulphate makes up two thirds of the products. There is nothing wrong with sodium coco sulphate in a cleaning product, it is an effective detergent, but insinuating that it is free of sodium lauryl sulphate is a dirty business.