How do you avoid clothing with a high amount of toxins in the fabric?

Depends: Which toxins are you talking about? The word toxin is used a lot but often no one knows what they mean by it. If you are talking about petroleum products you might opt for organic clothing or natural fibers. Still, those may contain bacteria or other "toxins" you are trying to avoid. First you need to find out what you r trying to avoid then you can find how to avoid it.