actually your prop is probably 1%(maybe 2%) benzyl alcohol depending homebrew,ugl, or pharm grade. so no matter your mg/ml, its still 1 or 2% b.a. USUALLY the case with prop is the concentration of the HORMONE that causes pain not the b.a. because you can 2 % b.a. in say deca and it will probably be painless. but having said that some people are sensitive to the alcohol but in my opinion it is usually the hormone.