You are getting into some complex, confusing, and controversial, issues here and I’ll do my best to unravel them a bit.
Prior to 2007 … mattresses in most states had to pass 16 CFR 1632 which was often called a “smouldering” or “cigarette” test because mattresses had to be fire resistant enough to withstand a smouldering cigarette without going up in flames. Some states (such as California) also had some tougher regulations that mattress manufacturers had to comply with.
In 2007 … an additional regulation 16 CFR 1633 which was called a “blowtorch” test was introduced which meant that mattresses had to withstand an open flame or blowtorch applied to the top and sides of the mattress for about a minute without bursting into flames (they measure the heat release for 30 minutes and it can’t exceed a certain limit). This new regulation was in addition to the old regulations so now a mattress manufacturer had to destroy 2 mattresses and pass two tests before it could be sold to the public. Mattresses are always tested and need to pass as a complete unit rather than the individual components being tested.
Because this second regulation was much more difficult to pass (and there is some controversy about its necessity at all and the reasons it was introduced) … the use of various chemicals and fire retardant methods became more common.
There are many methods that are used to pass these regulations and in many cases it is a combination of methods that are used together to pass a particular mattress or mattress foundation combination. The methods that are necessary and the combinations used depends on the combustibility of the mattress materials and ticking and quilting and the mattress has to be self extinguishing so that it doesn’t create “flashover” as it keeps burning
Some of the methods and materials include foams that have chemicals or other materials (such as carbon fibers) added to make them less combustible (although fire retardant foams are uncommon with mattresses and more common with furniture), a “sock” that encloses the inner components of a mattress or a quilting material that is part of the mattress cover that are made from non woven fabrics that have fire retardant chemicals added, various types of inherently fire resistant fabrics or combinations of fabrics (such as rayon and polyester impregnated with silica) that don’t contain any added chemicals (this is very common), and natural fabrics such as cotton that has boric acid added to it. Wool can also be used in certain densities and weights to the quilting of a mattress to pass the regulations but this is a more expensive fire retardant method even though it is the most natural. In many cases a mattress uses a combination of these methods to pass the regulations. There is some more information about fire barriers in this page and in post #2 here and in post #4 here.
A prescription allows a manufacturer to build a mattress and sell it to an individual that hasn’t passed the fire regulations. In most cases this involves the removal of the sock or the viscose layer in the quilting but they may still use the fire retardant foams or synthetic fibers in the mattress rather than special ordering these materials without the fire retardant components or removing them and changing the feel and performance of the mattress.
So a prescription mattress may be “safer” because some of the fire retardant layers or methods aren’t used (if the fire barriers that are removed were “unsafe” in the first place) but it doesn’t guarantee that all the materials are safe.
Safety is the real issue that most people want to address and this has much more involved than just any possible fire retardant chemicals that some mattresses use. Different materials can be more or less “safe” than others in terms of what is in them or any potential harmful offgassing or harmful chemicals that may leach or become part of household dust . Even though in North America most polyfoam and memory foam has been tested for offgassing and harmful ingredients (through programs such as CertiPur) … some batches of foam may not be fully cured so they may be more “harmful” or affect more sensitive people even though they have been spot tested. The manufacturing of foam is not as "exact’ a science as most people may believe and there may be unreacted chemicals or uncured foams that slip through. In other cases … some people are much more sensitive than the testing protocols so they may still react to certain types of materials or foams or glues used in a mattress even though for the large majority of people they are considered “safe”. There has also been very little research done into the long term effects of chemical combinations rather than just specific chemicals by themselves.
Offgassing itself is only one of the issues involved as well (and what you actually smell may not be harmful because some of the VOC’s that can be most harmful have no obvious odor) because as certain materials degrade and break down over time … they can become part of the household dust and could cause harm with ongoing exposure to the chemicals used to manufacturer the foam itself even though there is no more “offgassing” involved at least at detectable levels.
So with all of this … the question becomes “how safe is safe enough for me” for any individual and unfortunately there is little documented information that will allow consumers (or anyone for that matter) to answer that question in all cases.
There is an interesting discussion about some of these issues here :huh: http://cr4.globalspec.com/thread/3496/memory-foam-or-foamy-memory[url=http://cr4.globalspec.com/thread/3496/memory-foam-or-foamy-memory]issues here[/url] and the Chem-Tox site here clearly shows that some people can be much more sensitive than others.
Because of this … for those who are unusually sensitive … then choosing materials that don’t use harmful compounds can be particularly important. The “safest” of these materials are innersprings or microcoils, natural fibers (that aren’t treated in their manufacturing), rubberized coir, latex, and even densified polyester (see post #2 here) or “soft solid” gel materials (see post #4 here) although neither of the last two are natural materials. Most people who are more sensitive than the “norm” would probably choose to avoid polyfoam, memory foam, and synthetic fibers completely regardless of whether they have fire retardant chemicals added to what is already a large number of chemicals used to manufacturer the foam.
Beyond this there is the additional “layers” of information about whether a material is synthetic, natural, organic, or green … all of which are often used in misleading ways in the industry. For example … blended latex uses a combination of synthetic and natural latex in its manufacturing but has usually passed various types of testing that are more stringent than CertiPur (such as Oeko-Tex) and are considered to be safe for close contact with babies because they don’t use the same harmful chemicals that are used in polyfoam and memory foam. Most people with MCS (Multiple Chemical Sensitivities) will do well with blended latex even if they can’t tolerate polyfoam or memory foam but some people want the additional safety margin of using latex that is made with natural latex only. There is more information about differentiating between all these types of “labels” in post #2 here.
Organic is another level of certification yet that mostly has to do with the growing and agricultural methods used to produce the raw materials (no pesticides and organic farming methods) that are used in natural latex layers although there is now organic latex as well (see post #6 here). In addition to this … the actual production methods used to manufacture latex cores can also be certified as being “organic” and a factory can also be certified as well. This means that you could use an “organic” raw material (such as liquid latex) but that the product or layer that was produced from it would only be natural (if the production of the latex core wasn’t certified). in most cases … natural latex and organic latex are very similar except one is certified and one isn’t. The organic certification provides some assurance that there are no pesticides or harmful methods used in the production of the material but these same methods can be used in materials that don’t carry an organic certification. There are some types of wool for instance produced in the US that are probably “purer” and use more organic farming and husbandry methods than may types of wool that are certified as organic … even though the manufacturer didn’t want the added expense (to themselves or the consumer) of having it certified as organic.
So if I had certain health issues or sensitivities and was looking for a mattress that was “safe enough” … I would focus on more natural materials or materials that are known not to cause any issues with even sensitive people such as natural fibers, latex (blended or 100% natural depending on preference and the degree of assurance someone is looking for), coir, innersprings or densified polyester. Sometimes this can involve some real research into which “natural” materials are really natural and which organic materials or products are really organic and which synthetic materials are really “safe”.
The safety of mattress materials can be a complex and difficult issue with a great deal of conflicting or uncertain information. Post #2 here also has more information and links that can help answer the question of “how safe is safe enough for me?” in more detail yet.
So hopefully this helps to unravel at least some of the confusion into “safety” and if I was sensitive and looking for the “least risky” mattress … I would not only make sure I had a prescription so that a mattress didn’t have to pass the fire regulations for me to buy it … I would also make sure that the materials in the mattresses were within my personal tolerance or belief in terms of “potential harm” and safety as well.