Some 40% of staff working in a state child protection and welfare bureau have not been vetted by gardai.
A watchdog has warned of significant concerns and serious deficit in the Health Service Executive's Carlow/Kilkenny division with staff not always notifying gardai of concerns about abuse.
The Health Information and Quality Authority (Hiqa) said there were major gaps in background checks on staff who had been employed in child protection prior to 2008.
Elsewhere, the inspectors found that not all staff understood all of their responsibilities under Children First, rules introduced to safeguard and protect children.
Hiqa said that after 644 initial assessments were recommended on children's welfare only 56 were completed within a recommended timeframe. And they also found evidence that gardai were not always involved in child welfare concerns at the appropriate stage and that communication was too informal.
Hiqa investigated 27 national standards for the protection and welfare of children as part of the Carlow/Kilkenny review. A third of those standards were "not met" and the remaining 18 were only "met in part".
Shortfalls were identified in informing gardai of welfare risks, training for social workers and the upkeep of records.
Social workers told inspectors that the only formal notification to gardai of issues such as sexual or physical abuse and child neglect was issued by the Child Protection Notification Management Team.
Hiqa said this could hinder a Garda investigation and risk a child's safety as information may not have been shared at a "critical early stage". The inspectors also found Kilkenny and Carlow had different systems for screening child protection referrals.
In one office, social workers carried out preliminary inquiry checks under the supervision of a duty team leader. But the other was "overly dependent" on the team leader, who carried out screening, checks and preliminary inquiries alone - resulting in significant delays in the process. In their absence, cases were often left on a waiting list - regardless of how serious the risk posed to a child.