In cosmetic safety science, few distinctions matter more than the difference between hazard and risk. A hazard is an intrinsic property of a substance — its potential to cause harm. Risk, by contrast, is the probability that harm will actually occur under specific conditions of exposure.
Consider water. In high enough quantities, water is hazardous — it can cause hyponatremia. But the risk of harm from drinking a glass of water is essentially zero. The same logic applies to cosmetic ingredients.
HumanSafe scores ingredients at actual use concentrations — not theoretical maximum exposures. An ingredient that scores poorly in isolation may score well at the concentration found in a finished product. This is dose-aware safety assessment.