Often people will point out that something is a known carcinogen, using that as evidence that it is dangerous However just because something is (or often may be) a carcinogen is an overly simplistic way of determining if something is dangerous or not The dose received from a carcinogen is very important in determining how likely it is to give you cancer
For example, every time you drive you're exposed to exhaust fumes from your car and those around you, which are carcinogenic However this doesn't mean you should be scared of getting cancer any time you're in a car, when in reality you're at far greater risk of being involved in a crash