South Australian Premier Jay Weatherill says he makes no apologies for intrusive testing of potential child protection workers.

Questions to job applicants now explore such things as sexual experiences and fantasies, fidelity, use of dating websites and "even history of one-night stands", the Public Service Association (PSA) said in a bulletin to its members.

There was a royal commission in SA over child protection failings including the Chloe Valentine case and now-jailed paedophile Families SA worker Shannon McCoole.

The inquiry made 260 recommendations to bolster the child protection system and Mr Weatherill described it as "an excellent chance for a fresh start".

The Public Service Association said it had been at odds for months now about a requirement for "existing employees to undergo intrusive psychological testing".

It said the Child Protection Department initially refused to consult the union, but that changed after the matter was taken to the Industrial Relations Commission.

'Incredibly private and probably irrelevant'

The PSA said there were ongoing concerns "about the relevance of the highly intrusive tests, which could have longstanding effects on future employment and personal relationships".

It said the questions were "incredibly private and probably irrelevant".

Despite the union's view, Mr Weatherill described the process as totally appropriate.

"It is sad that we have to have this level of intrusion and scrutiny, but the truth is that we've already seen in the past that some people will try and infiltrate their way into these roles so that they can get access to children," he said.

"The interests of the children are paramount — that comes first — and it may mean that comes into collision with some other issues, some other rights around privacy.

"But that's the sad fact of life now in our modern era."

The union also cited concern about how securely the data would be stored and whether it would be accessible within other public sector agencies, and potentially beyond.

PSA official Nev Kitchin expressed concern for people's future job prospects, depending what data was stored.

"If a person refused to answer one of those questions, what difference would that make to the test?" he asked.

"If, overall, they're deemed to be unsuitable, how do you determine that?

"Where do you then put them in government, what are the implications for that person in relation to trying to find work in other government departments, where does the information go to?"