The Center for Environmental Health, based in Oakland, said it has told Walmart, Toys R Us, Target and Amazon, among others, they are selling products that contain the flame retardant chlorinated Tris -- a substance that has been banned from children's nightwear since 1977, the San Francisco Chronicle reported.
California added chlorinated Tris to a list of known carcinogens, and the center says that means products must carry warning labels if they contain significant amounts.
The center said it bought products from retailers in October and tested them.
"You can say, 'Maybe I'll luck out and go to the store and get a product that doesn't have this chemical in it,'" Caroline Cox, the research director, said. "But on the other hand, we found enough products that do contain chlorinated Tris that we would like to get this problem taken care of. I don't want anybody to have to worry when they need to go buy a crib mattress for their kids."
The center said it sent legal notices to nine companies last month and planned to add 15 more Thursday.