The survey by the National Highway Traffic Safety Administration found most of these 500,000 talkers are drivers of sport-utility vehicles and minivans on the road during nonrush hours.
Female drivers are more likely than male drivers to talk on their mobiles, with female drivers of light trucks almost twice as likely to use their cellphones as males driving the same type of vehicles. User rates were higher for drivers during the week than on weekends, and more suburban drivers than rural ones used phones.
The report comes amid a growing national debate over the safety of cellphone use by drivers. New York banned use of hand-held cellphones last month, and a number of other states including Georgia, Pennsylvania, Utah and Wyoming are considering similar restrictions.
Federal regulators said public concern spurred the survey and another study is being conducted on how cellphone use affects driver performance, but no release date has been announced. The study is one of the first to quantify cellphone use through observation rather than by phone survey. Data collectors, who also checked seat-belt use, observed more than 12,000 vehicles daily for two months during the past fall at hundreds of highway intersections across the country.
The report doesn't address accidents linked to cellphones. NHTSA has other data that show during 1999, police officers cited cellphones as contributing to car accidents in 93 cases. During 1991, police officers cited the phones in seven cases.
The Cellular Telecommunications and Internet Association, an industry group here, says phone use shouldn't be singled out as a safety hazard for drivers. "We know people use their phones in their cars, but phone use is just one of many distracting activities," Dee Yankoskie of the group said. "We need responsible use."
Driver distractions such as eating or tuning the car radio contributed to 11% of the fatal crashes during 1999, resulting in almost 5,000 fatalities, according to NHTSA crash data not included in the report. The Cellular Telecommunications and Internet Association has been working to educate the 109 million cellphone owners in the U.S. on the importance of attentive driving while on the phone, pushing for education rather than legislation.