Cell phone usage is being blamed for several problems this week as a University of Utah study found that cell phone usage on highways causes traffic jams.

In addition, the French government said mobile handsets can be bad for children, and Massachusetts law enforcement authorities said a hit-and-run fatality was caused by a man text messaging on his cell phone.

David Strayer, a psychology professor at the University of Utah, said new research not only showed that the cars of drivers talking on cell phones tended to move slower, but also that the conversational activity tends to cause traffic to show down.

"At the end of the day, the average person's commute is longer because of that person who is on the cell phone right in front of them," Strayer said in a statement. "That SOB on the cell phone is slowing you down and making you late."

The Utah study is scheduled to be presented during the U.S. Transportation Research Board's annual meeting later this month; the board is a unit within the National Academy of Engineering and Institute of Medicine.

The study adds to previous research conducted by Strayer's team, which demonstrated that the reaction of young adults talking on cell phones is as slow as the reaction times of senior citizens. The Utah research group also established that conversation -- and not the use of hands-free phone devices -- is the main distraction while driving and talking on cell phones.

In the new study, the Utah team found that the costs of delay and traffic jams can be deceptively high. "If we compile the millions of drivers distracted by cell phones and their small delays, and convert them to dollars, the costs are likely to be dramatic," a member of the Utah team reported. "Cell phones cost us dearly."

Meanwhile, the French Health Ministry this week reported that excessive use of cell phones by children should be avoided. While the French agency noted that there is no conclusive evidence that cell phone use causes any harmful health effects, the agency suggested that use of mobile phones by children should be curtained as a cautionary measure.

"One should use a mobile phone with good judgment, avoid calling when reception is poor, or during high-speed travel, and finally, keep the telephone away from sensitive areas of the body by using a hands-free kit," the agency stated, according to the Reuters news service.

In Massachusetts, a man was charged this week with text messaging on his cell phone while driving his SUV in a hit-and-run accident in which a 13-year-old boy was fatally injured. Prosecutors in Taunton said that Craig Bigos told them he thought he hit a mailbox while he was text messaging on his cell phone.

Bigos was released on bail in the incident; he pleaded not guilty in the incident.