Isotherm is made from recycled PET bottles (“plastic” cooldrink bottles) that are heat bonded without any chemicals or added fire retardants.  Polyester is super safe and has natural fire-retardant properties.  The product is basically the same as the polyester used in pillows and duvets.  No one can say that he/she will never return into the ceiling after installing insulation.  If the geyser bursts, an alarm get installed, the roof leaks, etc, it is comforting to know that there is a safe itch-free insulation material on the ceiling.