In the war against child abuse, protective service workers are manning the front lines. If a youngster dies from maltreatment -- the fate of an estimated 1,200 children in 1986 -- these social workers get the blame for "the system failing."

The rest of the time they may be resented by the same parents they are trying to help. And always, there is a mass of paperwork, an overburdened court system and a society that considers the profession only slightly more important than slinging hamburgers in a fast food joint.

Not surprisingly, social workers don't last very long working in protective service. In one national survey, a third of the workers had been in their jobs for less than two years. Burnout and the threat of burnout are constant problems; when they occur, it is the children who suffer.

Pro-Child, Arlington County's child protective services program, is an exception to the burnout epidemic. Its nine social workers have been there an average of 7 1/2 years, a fact they attribute to high morale and mutual support. But the problems they face in the county of 158,700 are the same of any suburban community, including a zooming caseload.

In fiscal 1981, 335 reports of suspected abuse were investigated in Arlington, including seven sex abuse. By fiscal 1987, that total had almost doubled to 612 -- 240 reports of physical abuse, 287 of neglect and 85 sexual. Roughly 40 percent of the investigations find the charge of maltreatment to be unfounded.

"The amount of actual abuse has risen steadily every year," says Pro-Child supervisor Marsha Moss. "We're beginning to have more neglect than physical abuse, which we attribute to the drug problem."

The explosive growth in sex abuse reports does not mean that a decade ago the problem hardly existed. "It was there, but we just didn't get any referrals," says Moss, who has worked at Pro-Child for a dozen years. "There's much more community awareness now, because of public education and the media."

Even now, she says, only "a fraction" of the incidents are discovered. Most of these involve children under 10; many are girls. Usually the abuser is a male parent, step-parent or relative, although "we're beginning to see a few cases where the female is abuser," Moss says. "The type of abuse ranges all the way from fondling to intercourse."

There are very few reported cases involving older kids, but "it absolutely has to be going on in that age group," she says. "Older children are more embarrassed and ashamed than younger children, and plus, there's a bond -- this has been going on in the family for a while."

Only rarely -- less than 2 percent of the time -- does child abuse in Arlington result in the removal of the youngster into foster care; a small number of kids are also placed with a relative. "Most of the families that we're working with are not sensational cases," says Moss. "They're troubled families, most of whom don't know much about parenting."

Of the nine social workers, five primarily do investigations; the other four, who teach parenting skills and provide access to community services, handle most of Pro-Child's 171 ongoing cases. In interviews, the caseworkers talked about the limits and handicaps they face:

Rhonda Walker, 30, who's been with Pro-Child 2 1/2 years: "It's hard for us to come in and expect changes in a couple of months or even a couple of years, because this is the way these people have been used to living for a much longer time. Take eating habits. Their mothers didn't buy them a lot of fruits and vegetables, so our clients do the same things with their kids, and just give them fast food. That's all they know. We try and teach them things about nutrition, but it's hard. We do see some change, but it's not always easy -- not as easy as some people may perceive."

Allyn Trautman, 51, 10 years at Pro-Child: "The key issue with a lot of people we work with is to be a consistent figure in their lives. I had a woman who screamed and shouted things at me, told me to get out of her life, and I would just give her a week or two to calm down and then I would go back. Even though there's a real push-pull, the fact that we're going to keep coming back means a lot to them. We're parental figures to those who have not had either consistent parenting or good parenting."

Helen Hughes, 55, eight years at Pro-Child: "One mother I've worked with comes from a very emotionally deprived background and does not know how to nurture. Since working with us, she's less inclined to lash out physically at her children. I wish she could be more emotionally supportive. But even though she isn't Mother of the Year, she does care. Considering her background, she is doing very well. But the community doesn't see that, because they're comparing her with where they came from. And therefore, they perceive that we are not doing our job, because we are not bringing her up to their standards. Sometimes, though, that just isn't possible."