Hi skubaman,
You can see my thoughts about CertiPUR in post #12 here. They use different limits for different chemicals that vary widely depending on the known “safe” limits for each chemical (you can see the specific testing limits here*) and IMO it is certainly a step in a good and and “safer” and more objective direction that can give most people a reasonable answer to the question of “how safe is safe enough for me?”.
ADMIN NOTE:*Always check CertiPur site for the latest guidelines available
Having said that … there will still be a smaller minority of people that are either more sensitive to even CertiPUR certified foams or that have health conditions such as MCS (Multiple Chemical Sensitivities) that may still find they experience some kind of reaction when they sleep on certain materials that for the large majority of people would be fine. Based on anecdotal feedback … this would be more common with memory foam, less common with polyfoam, and least common of all with latex. Some people may also find that they are only sensitive to specific versions of each of these materials made by a specific company and not to others or in some cases they may find that they are sensitive to specific batches of the same material and not to others because there may be some variation in the formulation of each batch or how it is cured or aired out during and after manufacturing. You can see an example of a specific product that I was sensitive to here although I am fine with most versions of memory foam.
Beyond a CertiPUR certification (or another legitimate certification) … the only way to know whether you are sensitive to a specific product that most others wouldn’t be sensitive to would be based on personal experience because foam manufacturers don’t release the specific details of the individual or amount of chemicals they use in their formulations which are proprietary. Some people that know they have a history of sensitivity to some versions of a specific category of foam may even choose to avoid that category completely just to reassure themselves and to have a larger margin of safety and lower the risk of their choices but these are all personal choices that would be based on “best judgement” that takes into account the specifics of each person’s history and circumstances.
Phoenix