A shortage of guards and a high rate of absenteeism are endangering safety and security at the D.C. jail and annex, union officials charged yesterday.

The staff shortage is acknowledged by both union and management officials. The high rate of absenteeism, the union says, is symptomatic of serious morale problems at Corrections Department facilities, which include the jail and annex in Southeast Washington; the reformatory at Lorton; and two youth centers.

Records of the D.C. Department of Corrections show that the 497 guards at the jail and annex have missed on average more than seven weeks of work each during a recent 10-month period.

Of that lost time, 3 1/2 weeks was charged off to sick leave,according to the records, which cover a 10-month period through July of this year.

The absenteeism is occurring when the jail and annex are understaffed by more than 50 officers, according to both the Department of Corrections and the union, Local 1550 of the American Federation of Government Employees.

"Our employes are abusing sick leave and missing work because the morale is low and the working conditions are getting worse," said Bernard Demczuk, the union's shop steward.

"We are working short. The stress level is way too high . . . Do we have to wait until there is a riot or an officer is killed?"

In a memo to Mayor Marion S. Barry last June, Corrections Department Director Delbert C. Jackson said his department is seriously understaffed and that any other reductions "would be disastrous" in terms of safety, inmate welfare and employe morale.

Another Jackson memo, written in April, said that the department had made a mistake in underestimating inmate populations and was faced with a "lack of staff."

Union officials said that a single guard is often left to watch 80 or more prisoners, and that inmates are easily able to assault other prisoners because of lack of supervision. Most of those assaults are not reported by firghtened inmates, officers said.

The union is scheduled to hold a press conference and rally today at the D.C. jail to urge Barry and the City Council to investigate the department's operations.

Union leaders cited the recent mass jailbreak in Jessup, Md., as one reason for publicly calling for corrective action. "We don't want to say, 'We told you so,'" one officer said.

Of the 7 1/2 weeks of absenteeism, 3 1/2 are sick leave, 2 1/2 annual leave, and 1 1/2 weeks include authorized leave without pay as well as "absent without leave."

The union has 1,500 members and represents 1,700 guards and other employes.

The union also notes that five inmates at the new D.C. jail have hanged themselves this year. "We can't help but think that perhaps at least one of those lives could have been spared if we had enough staff to do our job properly," Demczuk said.

The guards also charge that their working conditions are unsafe for several reasons. These include:

A quarter-million dollar electronic security system at the new D.C. jail has malfunctioned since its installation in 1976.

Untrainned CETA (Comprehensive Education Training Act) employes are used as armed guards over inmates, including standing watch at Lorton's prison towers, a violation of the CETA rules.

Correctional officers are assigned noncorrectional duties.

There is too little training. "If we are lucky we receive two days of inservice training per year," Demczuk said. He said the American Correctional Association standards call for a minimum of two weeks per year.

In a statement prepared for release today, the union rejected Jackson's explanation that his budget won't allow additional hiring.

"Budget constraints are certainly one reason for the staffing shortage and its adverse results," the statement said. "But we also question management's allocation of monies . . . we see too much waste."

The union cited as an example a management study that showed $120,000 worth of wasted food each year.