AS OF JAN. 1, 1977, 82 per cent of the city's 2,200 retired police officers were classfied as "disabled," as were 83 per cent of the 1,000 retired firefighters. Can it be that these careers are all that hard on a body? Of course not. The evidence won't support any such theory. As staff writer Ron Shaffer noted in a report last Sunday, these "disability" rates are way higher than those of similar cities: Los Angeles has four regular retirements for every disabled; in Detroit, it's seven regular to one disabled; and in New York, 13 regular to one disabled. In Washington it works the other way around: There are four disability retirements for every regular retirement.

Why is this? One must begin with the fact that the system makes disablity retirement a greatly preferable and extremely accessible thing. A retiree on disability generally receives two-thirds pay, while an officer or firefighter who retires optionally after 20 years receives half pay. Retirees also receive pay increases when active officers get them. But - and here's a big bonus - the disabled pensioner isn't taxed. All of this means that the benefits are among the best in the country, under a system built up by Congress over the years to aid recruitment.

In Washington, of 170 police officers and firefighters who applied for disability pensions last year, only five were refused. A city budget expert estimates that even if the system were stopped right now, with everyone on retirement today living a normal lifespan, the cost of discharging outstanding obligations would be between $1 billion and $1.5 billion. Obviously this amount would be less if there had been more regular retirements and fewer disability payments.

Back when police and fire departments were smaller and short-handed, one could justify a generous system to attract recruits. Even now, for that matter, few would begrudge generous payments to those whose abilities to function have indeed been impaired in service to the community.

But somewhere along the process that includes a retirement board, police and fire surgeons, recordkeepers and various layers of lawyers and doctors, the system has spun out of control. To begin to gain control of it, activities of the retirement board must be made more open - and the mayor needs to oversee the board's activities more carefully. A fundamental flaw in the system is the limit now placed on most board decisions, in which the only alternatives are to find the applicant disabled or not disabled. Instead, there should be a system of degrees of disability.

Unfortunately, however, concern about disability payments seems to materialize only briefly when some top official retires. And that brings us to the departure of Police Chief Maurice J. Cullinane. We're not in a position to asses with any authority the medical circumstances surrounding the chief's particular case. Nor is it fair to argue that any police officer or firefighter who is awarded seemingly excessive payments should voluntarily forego them on principle.So perhaps it was unrealistic to expect a chief to set an example in this instance. In any event, there have been many other demonstrably worse cases than his.

But the system has run amok. With a new police chief taking over, Mayor Washington, the city council and Congress should seize the opportunity to overhaul the system in a way that will continue to compensate those who deserve it while ending the practi ces that have encouraged enormously costly abuses for all too long.