I never gave that any thought (till now) as I treat all chemicals as toxic (especially the ones that flash off/vaporize quickly) but I went into the kitchen & looked at the can of brake kleen and it is non chlorinated so I think I'm good (& no I don't use it inside!). Just me I dont see a problem with blowing out the carb bowl with it even if it was chlorinated tho my favorite brand (cheap) is no chloride (done it many times) in a well ventilated area tho (car near the shop door/door open)