I think the question is a little larger, and should include not just risks of the chemical but the benefits. I have been on stages on three occasions where there was a curtain which caught fire and did not self extinguish. One was very new and other two had valid certs. Know a lot about two other incidents with new curtains. One was on opening day of a major pac. All cotten curtains, all quartz lights. The benefits of flame retardant need to be studied, especially in an era of LED.