Your couch probably has flame retardants embedded in the foam which have been linked to cancers and a range of other problems from obesity to reproductive defects.  A growing number of studies in humans and animals suggest that the problems are real and many scientists don’t think the flame retardants are worth the risk.

http://kristof.blogs.nytimes.com/2013/11/23/are-you-sitting-down-on-a-couch/?_r=0