Cotton fabric is a natural fiber and should cause no problems on it's own, chemical dyes should not cause a problem if they are rinsed out enough during the manufacturing process. What most people are allergic to including myself, is the surface 'dressing' which is added to the fabric after rinsing and before being rolled up. It gives the fabric 'body' a lot like starch does. It is important to wash this out well if you are sensitive to these things. I believe a lot of my allergies come from working in the textile industry over 30 yr period. The worst thing was when I had to use a big industrial winding machine which went so fast all the dust fluff and dressing was in the air to breath in all around me. I get that burning sensation up my nose throat and into my lungs. I am on steriod meds now for life! ( Allergies and asthema) I am happy using my recycled fabrics etc but still give them a good wash too!
Gal
PS It is possible to buy organic natural dyed fabric but it is usually very expensive and not available in huge yardages, usually from studio textile designers.