People commonly have misperceptions about what's dangerous and what isn't. Based on a review of the scientific literature on various risks summarized in "RISK: A Practical Guide for Deciding What's Really Safe and What's Really Dangerous in the World Around You," here are a few examples.

RISKIER THAN YOU MIGHT THINK

* The sun, a natural risk that doesn't evoke great fear, causes 1.3 million skin cancer cases and 7,800 melanoma deaths in the United States every year.

* Medical mistakes, anything from errors by doctors to misfilled prescriptions, kill as many as 98,000 Americans a year. And that's just in hospitals.

* Air pollution indoors, where we spend 90 percent of our time, is often worse than outdoors. Particularly in schools.

* Food poisoning sickens approximately 76 million Americans a year, and kills 5,000.

RISKS THAT AREN'T REALLY RISKY

* Nuclear radiation, a man-made radiation risk, is a weaker carcinogen than most people think. It's caused only about 500 cancer cases among the 90,000 survivors of the atomic weapons in Hiroshima and Nagasaki.

* Hazardous waste, according to the Environmental Protection Agency, is one of the smallest environmental risks we need to worry about.

* Cell phones aren't a plausible cause of cancer. They don't emit the kind of radiation that can cause mutations of our DNA and lead to that disease. -- D.R.