Why a hazard score isn't a risk score
A hazard is what an ingredient could do at some dose, in some test. Risk is what it's likely to do at the amount in your moisturizer, on your skin. Hazard-based ratings can flag an ingredient because of a high-dose animal study, while a well-studied active gets a middling score simply because it's potent.
That's why DemythSkin scores efficacy and safety separately, weighs how much of each ingredient is in the formula, and grades each one on human evidence. A product can be very gentle and do nothing, or effective and a little irritating; you should see both.
Comedogenic ratings, used carefully
Many pore-clogging ratings trace back to rabbit-ear tests on pure ingredients, which often don't match what happens on human skin in a finished product. We flag pore-cloggers by group and position rather than by a single number; see the acne & pore-clogging checker.