Hi upticka,
Just to add a little to the information that Claudia posted (thanks Clawdia :)) every mattress sold in the US has to pass the fire regulations (16 CFR 1632 and 1633) and a prototype has to be tested for fire resistance in order to be legally sold in the US. There are many people that are concerned about “chemicals” in their mattress that are used to make them fire resistant so the regulations have an exception that allows people to buy a mattress that hasn’t passed the test with a prescription from a licensed health professional (chiropractor, naturopath, doctor etc). As Clawdia said it’s a very simple matter to get the prescription and they will even supply you with forms that you can take to your health professional.
I would also be aware that there are also “safe” fire retardant methods and many mattresses don’t use “chemicals” to pass the fire regulations (unlike some of the information on the Sleep Essentials site). There is more about the fire regulations and fire retardants in post #4 here and more about safe fire retardant methods in post #2 here.
Phoenix