Bikes: the helmet's value.

Though head injuries are the leading cause of bicyle-related deaths, fewer than 10 percent of U.S. bike riders wear helmets. In the Dec. 4 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, the Centers for Disease Control (CDC) offers the first estimate of the U.S. toll taken by this failure to don head protectors: one death daily and another head injury every 4 minutes.

In reviewing five years' worth of data from two national registries of health statistics, CDC researchers identified 2,985 bicyle-crash fatalities involving head injuries and 905,752 nonfatal, bicycle-related head injuries. Based on the reduced risk of head injury documented among bicyle-accident victims wearing helmets, Jeffrey J. Sacks and his CDC co-workers conclude that between 1984 and 1988, helmet use by all U.S. bicyclists "could have prevented as many as 2,500 deaths and 757,000 head injuries"--primarily in children.

Childhood deaths from bicycling roughly match the death rate once associated with a bacterial meningitis known as "H. flu," notes Barry D. Weiss of the University of Arizona in Tucson. "While we now immunize all [U.S.] children against H. influenzae, we do little or nothing on a national level about bicycle-related deaths," he writes in an editorial accompanying the report.