The organic underwear is probably most important garment for you. Next to the skin for many hours, it is of out most importance to protect it .  Skin problems and sensitivities are getting more and more common and are difficult to eradicate once there. So be good to yourself as well as to environment. We don't need pesticides, insecticides and other chemicals next to your skin and not in our soils and waters.

By the way, newer fibers like bamboo or soy have great properties - stronger than silk, cotton or wool, it wicks moisture better than cotton. It also deters bacteria and body. Worth considering.