If you want to know more about whether a product is safe, be skeptical researching on the internet. Most so-called information pages will be manufacturers promoting their own products and often claim their competition uses unsafe materials. This makes life confusing for the public trying to find out the truth. If you look hard enough and long enough, you will always find something to be concerned about.
I have worked 35 years in the mattress industry and have seen many different materials used in mattresses so I hope my impartial advice will help you understand a little more about whether you should buy Polyester, Latex or a combination of both.