Hi mattressmaven,
There is some information about the 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
An organic certification requires that the natural latex content is no less than 95% of the latex (not 98%) and that any additional chemical inputs and other criteria meets the standards that are summarized here.
There is also more about the different types and blends of latex in post #6 here but 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 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.
Phoenix