Seventy-four percent of Chicago's inner-city children have witnessed a slaying, shooting, stabbing or robbery, according to a study, and experts worry about the impact such violence has on youngsters' mental health.

"People think if they're chronically exposed to this kind of violence kids adapt to it," said Dr. Carl Bell, a psychiatrist at the University of Illinois School of Medicine. "But they're wrong. If children who witness crimes appear withdrawn or silent, it's a symptom of the damage. They just shut off."The survey of more than 1,000 elementary and high school children on Chicago's South Side found that of students who witnessed violent crimes, in about half the cases the victim was a friend, family member or neighbor. In addition, 46 percent of the students reported that they had been victims of violent crimes themselves.

And the victims aren't receiving the attention and counseling they need, said Bell, also head of the Community Mental Health Council, which conducted the survey.

"There are basically three areas where people impacted by witnessing violence show up - in the criminal justice system, in the mental health system or as a problem with the Board of Education," Bell said.

He said witnessing or being a victim of violence teaches that violence is a way to address problems. As a result, the youths often have difficulty dealing with their own aggression, Bell said.

"You also see elements of nihilism," he said. "If you see people getting killed, you start to think that dying soon is inevitable. Some kids get chronically depressed, withdrawn."

He said officials need to develop a consistent policy on dealing with the children.

"They could develop from that a cadre of professionals able to deal with homicides and other community violence like shootings or stabbings," Bell said.

"That's also true in Detroit," said Anne Milko-Delpier, program coordinator for Detroit's Family Bereavement Center. "There are not a lot of professionals who are trained to deal with kids who witness violent crimes like homicides."

Milko-Delpier said Detroit's court system refers families of homicide victims under the age of 21 to the center, a program run by a non-profit private social services agency called the Children's Center.

She also said she was surprised at the Chicago survey's figures, adding she believes the number of children witnessing violent crimes in Detroit is definitely lower, although no study has been done.

Officials in Philadelphia also could offer no comparable figures on children who witness violent crimes. But the number is probably increasing, said Kemi Adeleye, a director at Families of Murder Victims, which deals with some of the young witnesses.

"Homicide crimes are getting quite common around here," said Adeleye, whose agency is associated with the Philadelphia district attorney's office. "But many say they just kind of get used to it. It's probably not so much that they get used to violent crimes, but rather it becomes such a frequent thing that they are no longer as shocked by it."