According to Insulfoam's MSDS sheet it is comprised of the following:
(The MSDS sheet which I'll link, is divided into two main categories, Non-Hazardous Components and Hazardous Components. On the Non-Hazardous Components side we have)...
Polystyrene CAS# 9003536 <92%
(Then on the Hazardous Components side)...
Pentane CAS# 109660 <2%
Polymeric film (no CAS registry # is given) 1-3%
Bromine Flame Retardant CAS# 3194-55-6 <1%
Incidentally CAS# 3194-55-6 is registered as Hexabromocyclododecane. And is the very chemical being banned globally.