Most tampons contain cotton fibers. Almost all the cotton grown in India now and much in China is genetically modified to contain BT right in the plant. BT is an insecticide. It becomes part of the genetic structure of the cotton and can't be washed out when the fibers are cleaned and whitened to go into a product. I think it's the BT cotton that's causing the problem in tampons.

There have been many reports of allergies to BT and BT crops worldwide.

BT is used as an organic insecticide, so it sounds safe. I've even used it in my own garden. But I had to wear gloves and use a mask if I was misting or I'd turn bright red from it. If I couldn't let it touch my calloused gardener's hands, just imagine what it can do elsewhere. I think most people have no reaction to it. But some do.

I don't know the solution to this problem, but it's a problem for many women. If you can find a brand that works for you, even if it costs more, it's probably a good idea to stick with it if you've already shown sensitivity.