Hi Mateo,
Cotton is one of the most heavily sprayed crops on earth and there are many people who wish to avoid pesticides or other potentially harmful substances or residues in their mattress (or their food and clothing) or who for personal reasons prefer to use materials that are a little more “earth friendly”.
The materials in your mattress (and your pillow) are also closer to your face and mouth and the air you breathe than the clothing you wear or other household furniture so some people are more concerned with the materials in their mattress than anything else in their home environment.
Post #2 here and the more detailed posts and information it links to have more information about safe, natural, organic, “chemical free”, and “green” mattresses and mattress materials that can help you sort through some of the marketing information and terminology that you will encounter in the industry and can help you differentiate between them and answer “how safe is safe enough for me” or “how green is green enough for me” or even “how organic is organic enough for me” so you can decide on the types of materials you are most comfortable having in your mattress. These types of issues are complex and are generally specific to each person and their individual sensitivities, circumstances, criteria, beliefs, and lifestyle choices.
There is certainly organic Dunlop latex available that is made with latex that is grown on certified organic plantations and that use organic methods to manufacture the latex. There is more about organic latex (GOLS certified) and organic certifications in general in post #2 here and the other posts it links to.
Phoenix