A number of reasons have been offered for the increase in violence. The ranks of those seeking public assistance have been swollen by mental patients released onto the streets in recent years. Clinic-based psychiatric social workers now routinely face clients who previously were confined to high-security mental hospitals.

Another cause is the changing nature of cases at welfare offices. Men who owe child-support payments are confronted by newly aggressive efforts to track them down. Social workers are being asked to deal with increasingly volatile issues in family disputes, particularly in child-abuse cases. Aggravating the problem is the recession, which has forced welfare cutbacks as need has grown.

"Social work gets more dangerous every year," said William Griffin, an adjunct professor of social work at the University of North Carolina at Chapel Hill. Mr. Griffin said he had been called in on about 75 assault cases around the country since he began counseling government agencies in 1985 about how to respond to such attacks. 'Yelling in the Wind'

"Many incidents get little attention," Mr. Griffin said. "I'm one of the few people who is collecting this information, and sometimes I feel like I'm yelling in the wind."

In fact, others are beginning to document the violence.

A 1,400-worker division of Kentucky's social services bureaucracy reported 225 threats and physical attacks last year, including 15 in which victims required medical attention. In one recent incident, a father accused of sexual abuse brandished a .357 Magnum during a meeting with caseworkers. In another, an assailant with a shotgun took a worker hostage, said Richard Newman, a branch manager in Kentucky's human resources agency.

"Our people have been kicked with cowboy boots, threatened with Coke bottles, poked with umbrellas, bit on the ears, grabbed by the hair and smashed into desks," Mr. Newman said. Small Towns, Too

A California report documented 58 cases during 1990 in which workers were struck, stabbed, beaten, or shot and 16 other cases involving other forms of physical assault.