Even though he's a law-abiding, peace-loving citizen, Dr. Joel Chinitz knows more than most people about firearms.

He knows the differences between revolvers and semiautomatic weapons. He can reel off brand names of weapons and talk about safety locks and other characteristics.

He knows this not as a gun owner but as a doctor who cares deeply about the dangers of firearms as a public health risk.

"This relates to my role as a physician involved in public health," says Chinitz. "Violence is a significant health-care problem. For young people, the risk of injury or death from firearms is greater than all the other medical problems combined."

It's a public health problem that he wants doctors to address, and he is setting the example.

The Fort Washington physician is a longtime member of Physicians for Social Responsibility (PSR), and he's now coordinator of its Firearms Violence Task Force.

The busy physician, who holds a master's degree in public health, is also medical director of the Physicians Assistant Program at Philadelphia University, but he nonetheless spends hours of his time on the cause of violence prevention.

Besides being coordinator of the PSR task force, he's also on the governing board of the North Philadelphia Firearms Reduction Initiative.

He speaks often at seminars and town meetings and visits public health clinics all over North Philadelphia to talk to doctors and health-care workers and to help build awareness of the issue.

JUST ASK THE QUESTION

For instance, he urges doctors to ask their patients an important but unusual question: "Is there a gun in your household?"

"This important but often avoided issue is a critical one for the medical community," says Chinitz. "We have to recognize that there are a significant number of firearms in these neighborhoods. And the professionals have to start talking about guns with their adult patients."

All this is dramatically different from the time when Chinitz, now 62, was training to be a doctor in the l950s.

"In those days, doctors didn't even ask people whether they smoked," he says. "Only gradually did we start to ask that question."

Similarly, until quite recently doctors never asked about domestic violence. And now, he believes, it's time to add questions about whether there's a gun in the house.

"And the follow-up question is, ŒDo you really need it?'" he says.

"We should point out that the risks of having a gun in the house are higher than without it. The goal is to persuade the family to get rid of the gun or to keep it locked and unloaded."

Because he's teaching others to deal with the firearms issue, Chinitz had to educate himself. He's talked to experts. He's done research about violence and public health, and he's invited police officers and responsible gun owners to bring firearms to the workshops he holds.

For instance, under Chinitz's leadership, PSR held a conference in October for the medical community that focused on screening and counseling patients about firearms safety. It included a presentation on the "anatomy of weapons" by Curt Hill, a responsible gun owner.

POSITIVE REACTION

The reaction of the health-care community to this emphasis has been positive, says Chinitz.

"Many doctors and others we've worked with say this is something that they hadn't thought about before and that they do plan to incorporate it into their office procedures," he says.

Chinitz is confident that the message is getting through and that health-care workers in clinics will soon screen their patients about guns just as they now routinely ask about smoking or drinking habits.

His work brings him in contact not only with the health-care workers but also with the youngsters in North Philadelphia neighborhoods, whom he meets at various community and town meetings. And this makes him even more convinced of the need for the medical community to address the issue of firearms.

"Every youngster in these neighborhoods has witnessed violence," he says. "There isn't one youngster who has not been affected by it."

Traveling all over North Philadelphia, from Allegheny to Girard, from Broad to 33rd, he lives a life far different from the days when he was a traditional doctor with a private practice.

His specialty was nephrology -- the branch of medicine that deals with the kidney -- and many of his patients used dialysis machines.

Helping them was rewarding, but in time he needed something more to satisfy his activist instincts.

"I spent so much time in the high-tech medical world that I felt isolated from the actual community," he says.

So in l990, he made a bold move. He sold his practice and went back to school, specifically to Temple University to earn a master's degree in public health.

THE DOCTOR IS IN . . . CLASS

His wife Joan was extremely supportive.

"She really encouraged me in this career change and has been involved ever since," he says.

Soon he was working at the Hunting Park Health Center doing primary-care medicine. And when Physicians for Social Responsibility began developing programs on domestic violence, he eagerly volunteered and helped to create the Philadelphia Family Violence Working Group, which included doctors plus representatives of varied women's agencies.

The group, which conducted workshops in health centers, is still an ongoing division of PSR and received a grant from the William Penn Foundation.

His work with domestic violence paved the way for his next big issue: Firearms violence as a public health concern.

Serving as coordinator of PSR's Firearms Violence Task Force, Chinitz also became involved in related projects such as the North Philadelphia Firearms Reduction Initiative, which targets youngsters at risk for delinquency and violence.

This dedicated activist is involved in other community projects, too. For instance, he serves as a volunteer at the Catholic Worker Clinic in Kensington, where he gives free primary-care medicine to those who come to the clinic. Often the patients are homeless, drug dependent or have mental illnesses.

Does he ever feel overwhelmed or discouraged about working on such daunting social problems?

"No," he says. "I get energized by being involved and trying to get others involved. It would be discouraging if I knew about the problem but wasn't taking any action.

"I look at the big picture, and then I try to do what is doable," Chinitz adds.

"The satisfaction is in focusing on a specific contribution that I can make. Even if I help one person, it's a meaningful experience."