L.S.
Sulfates are hard on colored hair; they also *may* cause cancer. Color-safe shampoos/conditioners may/may not contain sulfates, you have to read the label. Sulfates = sodium lauryl sulfate (SLS). SLS is also known as sodium laurilsulfate or sodium dodecyl sulfate (SDS or NaDS0).
I use Burt's Bees Color Keep Shampoo; it's sulfate free.