Nearly two-thirds of nurses, paediatricians and social workers who work with traumatised children have psychological difficulties themselves, potentially damaging their ability to work effectively, a new study shows.

Researchers from the University of Glasgow found that people on the front line dealing with injured or vulnerable children developed secondary traumatic stress and reported high levels of chronic difficulties in their family life.

Dr Joan Burns, a clinical psychologist said: "Police and ambulance workers have developed black humour which enables them to cope with traumatic events, but those dealing with children feel this is inappropriate.

"Many people working with children said they felt helpless in their inability to protect the children. People who suffer from secondary stress find they avoid certain situations and suffer from intrusive thoughts and images when they are doing something completely different," she said.

Researchers questioned 119 people who worked as medical staff in a children's hospital, social workers in the field of child protection or child telephone helpline volunteers. Eighty-five per cent of social workers reported trauma symptoms.

"Results suggest that more research is needed to find ways of protecting people who work in this field," said Doctor Burns.