Hi lawrencekansas,
The latex is Oeko-Tex certified for harmful ingredients and VOC’s and the polyfoam and memory foam is CertiPur certified for the same thing. These are not 'organic" mattresses but the certifications provide the assurances that the large majority of people need to be comfortable with knowing that their mattresses are “safe”.
ADMIN NOTE: *Removed 404 link|Archived Footprint: ertipur.us/pages/for-consumers/find-products/
Of course the whole idea of “how safe is safe enough” is relative to each person’s own beliefs and the “degree” of safety or assurance they are looking for so some people may also choose to do much more extensive research into the complex, controversial, and conflicting information about natural, safe, ecofriendly, or organic materials and for those post #2 here and the information it links to would be a good starting point.
They sell Savvy Rest mattresses which use very good quality materials but as you mentioned can be more costly than many other manufacturers that use the same materials (100% natural Dunlop latex or 100% natural Talalay latex and organic wool quilted/cotton covers). All the latex you are likely to encounter whether it is blended or 100% natural would be “safe” and “non toxic” in most people’s opinion.
There are some general guidelines in the mattresses section of the site which will help you understand some of the theory behind different materials, layer combinations, and mattress designs and how they can match different body types and sleeping positions but there is no formula that can take someone’s weight and sleeping positions and “translate them” into a mattress design. Your body will tell you much more than any theory. Your own personal testing on mattresses where the retailer or manufacturer can tell you what is inside it is always the most accurate way to make your choices and if you do choose to go with an online choice your local testing and feedback on a more detailed phone conversation will also help them to help you make the best choice between the mattress they make or sell.
The only real answer as far as what is “best for your back” is the mattress that keeps you in the best alignment in all your sleeping positions but this may be a very different mattress for different people.
“Finding the experts” that already know what you would otherwise need to learn is always the most effective approach.
Just in case you haven’t read it as well … post #1 here is the most important post on the forum and will give you all the basic information you need and a step by step approach to help you make the best possible choices.
Phoenix