Hi JannyGoats,
In general the most “risky” materials would be any memory foam or polyfoam (depending on the specific type because some of these are fairly “safe” by most people’s standards if they are made in North America or are CertiPur certified) which are made primarily from petrochemicals, the glues in the mattress (water based glues are generally safer than solvent based glues), or some types of fire retardant materials. Even though inherent fabrics are chemically bonded in their manufacturing and don’t have free chemicals added to them or that are used to coat them (which is often the case with furniture) … some types do have some ingredients that would be more “risky” such as formaldehyde or antimony and others that are added to the plastic dope before it is spun into a fiber. Many inherent fabrics are actually blends of different types of material to form the char, to keep the char together so the fire can’t penetrate into the fuel underneath, and often other fibers that are used to make the fire barrier more “comfortable” and lofted. There are even some inherent fire barriers that are Oeko-Tex 100 certified such as here.
Mattress manufacturers don’t generally use fire retardant foams (unlike furniture manufacturers that often use polyfoam that has added fire retardant chemicals to the foam) and rely mostly on barrier methods that surround the fuel inside the mattress (such as the foams) to pass the fire regulations.
I wish the information about all the different types of fire barriers that are in use and their exact composition was easier to obtain but the specifics of the materials that most manufacturers use are mostly proprietary and “secret”. After probably hundreds of hours of reading and research I still don’t have anywhere near all the information or knowledge I would want.
With a doctors or health professional’s prescription a manufacturer can make a mattress for a customer that doesn’t use a fire barrier at all and there is an added bonus that there is no tax on the mattress.
In general terms … I would be most “comfortable” in terms of safety with fire barriers that use needle punched or densified wool or with viscose/silica fire barriers (sometimes blended with polyester to create loft). Aramid or Para Aramid fibers (such as Nomex or Kevlar) would also be safe IMO but they are more costly and have a stiffer “feel”. Kevlar thread is used in most fire barriers so the flames can’t go through the needle holes. There is a little more about fire barriers in post #2 here. IMO … the “safest” or perhaps “least harmful” of the chemicals is Boric Acid.
Phoenix