More than 1,150 children referred to health boards in the Eastern Regional Health Authority are not being helped because of a shortage of social workers, according to an IMPACT survey.
The union's assistant general secretary for the sector, Mr Sean McHugh, estimates this is around one-quarter of all cases.
The worst affected community care area is Area Four (Crumlin-Drimnagh), where there are eight vacancies for social workers and 280 unallocated cases. Fostering and foreign adoption applications are also severely affected by the lack of social workers.
Mr McHugh says there are 40 social worker vacancies out of 270 posts. Those hardest to fill are in Dublin, where the cost of living and difficulty acquiring accommodation made it difficult to recruit and retain staff.
IMPACT gave the following breakdown of the problem. Area One (Dun Laoghaire-Rathdown) is down half a post and has a team leader on maternity leave. It has 140 unallocated cases.
Area Two (Dublin South-East) has 2.5 vacant posts and 38 unallocated cases. However, the area also contains the office for asylum-seekers in Mount Street and this has 110 unaccompanied child refugees attached to it who are in need of monitoring.
Area Three (South Inner City) has two vacancies and 80 unallocated cases. Area Four, referred to above, is the worst affected with eight vacant posts and 280 unallocated cases.
Area Five (South-West including Tallaght) has two vacancies and 55 unallocated cases. Area Six (Dublin North-West) has 6.5 vacancies and 150 unallocated cases.
Area Seven (North Inner City and Ballymun) has five vacancies and 200 unallocated cases. Area Eight has eight vacant posts and 60 unallocated cases.
Area Nine (Kildare) has no vacancies and 45 unallocated cases. Area 10 (Wicklow) has 2.5 vacant posts and 110 unallocated cases.
A spokeswoman for the ERHA said yesterday that around 600 of the 1,150 cases had been assessed as involving child abuse and that these children were being prioritised.
Allocations would be on the basis of need and urgency. The remaining 550 cases involved a wide range of problems.
Since August 1999, 17 new social workers had been recruited and 15 more were in the process of being appointed. She accepted there was a recruitment problem in the Dublin area.
"There are simply not enough social and care workers to provide the services the Government has promised", Mr McHugh told union delegates yesterday. These cases had all received provisional assessments but no social worker was available to carry out a full investigation.
This confirmed the union view that there was "no meaningful personnel or manpower policy in the child protection area".
"In 15 or 20 years' time we could be investigating the scandal of child protection at the turn of the millennium. It won't be possible for people to use the old argument that we would have done something if only we'd known.
"If the repeated warnings of staff are not heeded, the finger of blame will be pointed at those in Government who allowed the situation to continue and at society for turning a blind eye."
Mr McHugh warned that IMPACT would "not allow the Government to blame staff who were being asked to do the impossible".
It might be public policy to encourage the public and professionals such as teachers, doctors and health workers, to report suspected cases of child abuse, Mr McHugh said, but this would simply lengthen the waiting lists in the present circumstances.
Delegates passed a motion calling for a five-year development plan which would provide comprehensive and easily accessible services for children and their families. These should include provision for extra staff and improved training.