Risk Versus Hazard

Herb Skovronek’s letter hit a sore spot in arguing that “the hazard from such incidental exposure is nil,” in reference to secondhand smoke (C&EN, Sept. 22, page 2). It worries me when someone who spent a good part of his career working on the control and detection of hazardous substances mistakes hazard for risk.

For a minute, let’s ignore benefits from a smoking ban that have nothing to do with health risk, like improperly discarded cigarette butts. Not only do smokers make the choice to expose themselves to hazardous chemicals, but they also choose to expose everyone around them as well.

Most people don’t like the idea of other people making such a decision for them, especially when these bystanders receive no tangible benefit from such an exposure. In assessing risk, it is also important to keep in mind cumulative exposure. The beaches and parks of New Jersey are likely not the only places people are exposed to secondhand smoke.

The concepts of risk and hazard are often confused. The hazard of a chemical is independent of risk. In risk assessment, one compares the magnitude of the hazard with the exposure to arrive at an idea of risk. Odor threshold is really a proxy for quantifying exposure to a hazardous substance. Exposure at the odor threshold may or may not result in a meaningful health risk. The vilification of dissenting opinions is often the refuge of a poor argument, but sometimes an argument is just lousy.

John Berry
Philadelphia