I'm surprised at all of the ignorant and unhelpful responses. The OP has a good question, and if you haven't done the research to understand why or why not to agree- then don't post a reply. There are definite concerns about the use of fire retardant in children's products. Here is a link to a CBS news story on the subject:
http://www.cbsnews.com/stories/2008/05/19/eveningnews/main4109418.shtml
The businesses that produce the chemicals want to endorse their good qualities and so of course they do not support the claims against their products. Flame retardants have been tested to show that they affect fertility and can cause neurological changes in infants and young children. We all have the chemicals in our blood because the government has been packing them in our products even after they were banned for a time in the 70s.
Is my toddler going to be trapped in her couch/chair during a fire? Uh, I would hope not. That would mean I tied her to it. Since everything else in my house will be going up in flames, I'm sure the chair won't matter. Personally, I'd rather have a chair with no treatment or non toxic fire treatments, which do exist.
I found this thread while looking for such a chair, so if someone has a helpful comment- please post it. Wooden is clearly an easy and good choice, but I'm curious too see if there are any already cushioned choices out there.