Sodium lauryl sulfate (also known as SLS), sodium laurel sulfate and its relative sodium laureth sulfate (SLES) are foaming agents commonly used in personal care products such as shampoos, cleansers, body washes and toothpaste to produce that lather. 

Why should you try and avoid Sodium Lauryl Sulfate ?

Research in America at the Georgia University medical centre indicates that sodium laureth sulphate and sodium lauryl sulphate can both react with other chemicals found in cosmetics to form nitrosamines and 1,4 dioxine, which are both known carcinogens. For this reason the American Food and Drug Agency classifies both sodium laureth sulphate and sodium lauryl sulphate as drugs when used in cosmetics. 

Most research seems to suggest that sodium lauryl sulfate is not a carcinogens, they are however irritants and has been linked to health issues ranging from eczema to canker sores.   However, since most products containing them are rinsed off quickly, they may not be cause for alarm. But if you are in the better safe than sorry camp, or if you have sensitive skin or are looking for a product for children, then you may want to avoid products containing SLS or SLES.

Products commonly found to contains Sodium Lauryl Sulfate 

Soaps
Shampoos
Bubble-baths
Tooth paste
Washing-up liquid / dish soap
Laundry detergent
Childrens soaps / shampoos
Moisture lotion / Moisturiser
Sun Cream

Looking for alternatives

Sodium Lauryl Sulfate Free Soaps
>> Nurture My Body Organic Baby Bar Soap SLS and Phthalate Free

Sodium Lauryl Sulfate Free Shampoos
>> Nurture My Body Fragrance Free Organic Volumizing Shampoo SLS Free for Fine, Limp Hair

Sodium Lauryl Sulfate Free Toothpaste
>> Nature's Gate Organics Toothpaste with Fluoride, Peppermint Whitening, 5 oz (141 g) (Pack of 3)

Related link EWG:

http://www.cosmeticsdatabase.com/ingredient.php?ingred06=706110&nothanks=1