Hi Saskin,
There is some information about the different types and blends of latex in post #6 here. All of the latex you are likely to encounter (either Dunlop or Talalay that is made with either natural or synthetic rubber or a blend of both) will have a reliable safety certification such as Oeko-Tex, Eco-Institut, or Greenguard Gold and based on actual testing I would consider any type or blend of latex to be a very “safe” material in terms of harmful substances and VOC’s. If certified organic latex is important to you then some 100% natural Dunlop latex has an organic certification but there isn’t any 100% natural Talalay latex that has an organic certification. There is more about organic certified Dunlop latex in post #6 here.
Most (although certainly not all) people that are looking for an “organic” mattress are usually concerned more with “safety” than whether the latex has an organic certification. There is more information about the three different levels of organic certifications in post #2 here and some of the benefits of an organic certification in post #3 here and there is more about the different types of organic and safety certifications in post #2 here and more about some of the differences between organic and safety certifications in post #2 here that can help you decide whether an organic certification is important to you for environmental, social, or personal reasons or whether a “safety” certification is enough.
If organic certifications are an important criteria for you then a retailer or manufacturer should be able to show you any certifications that would apply to their mattresses and materials to confirm that any organic claims are legitimate.
Phoenix