Found this, page-21

Hi not really sure if this answers your question and do not intend to pretend my comment are definitve merely a point for discussion as none of the chemical compounds involved are made clear.

the first Fire block is a consumer applied product. doesn't contain bromides.

Note its FAQ page has the following;

"Meets most requirements for fire marshals and NFPA 101, Safety Life Code. "
the Second fabric-back has the following comment on their website. they are a fabric treater.
"Natural fiber fabrics, such as cotton, linen, silk, and wool can be treated to meet all flammability standards. Most synthetic fabrics, such as nylons, acrylic, polypropylene, and acetates are nonabsorbent fibers that are difficult to treat. However, rayon and polyester can be treated. "
the Third states on their Website
"NOT INTENDED FOR CLOTHING!

Does not work well on acrylic, acetate, Nylon or fabrics coated with Teflon, permanent press or other resistant coatings. (A test - if water beads up on a fabric, this product will not be able to penetrate.) Leaves no visible residue and will not discolor the fabric. Apply with a spray bottle or garden sprayer; never dip."
Just some info for speculators
Also I will admit that I got so bored with the previous list that I didn't get to Websters fabrics. they seem to be using flame resisitant techniques that date from 1978 and do not seem to make any real claims regarding toxicity.