NHS staff have been subjected to sexual harassment, groping, upskirting and even rape by bosses, fellow workers and patients while at work, a report reveals.

Nurses, care assistants, cleaners and administrative staff have ended up suffering serious mental trauma, and even quitting their jobs after becoming the victims of sexual misbehaviour and crime.

The findings are contained in research published on Thursday by Unison. The union is urging ministers to overhaul the Equality Act 2010 so that employers would once again be held liable if they were aware that incidents of sexual harassment had occurred but did not then take action.

In one incident a member of a healthcare team upskirted a colleague and then “accidentally” shared the images with another worker. In another, a female administrator in an all-male team was visited regularly in her office by a colleague who asked her to have “a one-night stand or a quickie”. A third case was of a staff member being sent nude images of colleagues using the dating app Grindr.

“Many nurses, cleaners and administrative workers feel they have to put up with appalling behaviour as nothing will be done. This is generally because the perpetrators are in a position of power or believe they are untouchable,” said Christina McAnea, Unison’s assistant general secretary.

The findings emerged from a survey Unison conducted of 8,487 NHS staff across the UK in May. Of them 695 – one in 12 – said they had been sexually harassed in the previous 12 months. Those cases included three rapes and one threat to rape.

Most of the perpetrators were colleagues (54%), though 42% were patients, some of whom were drunk. Most victims were women (82%). Many perpetrators (61%) were older than their target and 37% held more senior roles in the organisation.

Some victims subsequently self-harmed, had suicidal thoughts or suffered a loss of confidence.

Ruth May, NHS England’s chief nursing officer, said: “We have a zero-tolerance policy when it comes to abuse, violence or harassment in the workplace and we will not stand for harassment or assault of any kind against NHS staff.

“Leaders of NHS organisations take these incidents seriously when they are reported, and we would want to provide the appropriate care and support to staff affected.”