Although often used interchangeably, hazard and risk are distinct and useful concepts. A hazard is something that can cause harm, while risk is the chance of that harm actually occurring in the real world. A hazard poses no risk if there is no exposure to that hazard. For instance, a shark feeding frenzy is an extreme hazard, but there’s no way I’m jumping into the water with them, so my risk is near zero — it’s never going to happen unless I fall or get pushed.
In medicine, carcinogens are a classic source of hazard/risk confusion. Many substances are carcinogenic (a genuine hazard), but only in high doses — much higher than anyone needs to worry about (a tiny risk). The state of California is notorious for classifying substances as carcinogenic without regard for the distinction between risk and hazard (like with coffee, most notoriously and recently). Media coverage of the issue, while suitably skeptical in many cases, also tends to ignore to the risk/hazard difference.
I focused on this distinction in a recent update to my the spinal manipulation chapter of my neck pain tutorial. Neck manipulation is not only a hazard, but a substantial one: the stakes are high, it’s obviously possible to hurt people seriously, even lethally. But what are the risks in the real world? Is any risk acceptable for benefits that are probably minor at best? And considering the high stakes? Understanding hazard versus risk is particularly important to this topic.