People using e-cigarettes will be asked to stick to nine designated smoking areas at next month's Royal Adelaide Show.

The new rule cannot be legally enforced but the show's general manager, Michelle Hocking, told 891 ABC Adelaide that organisers would be making a polite request for cooperation.

"What we're doing this year is we are asking politely - if you do want to have an e-cigarette can you go to a smoking zone," she said.

"And we're sure other members of the public will help us police that."

Ms Hocking said organisers made the call in the interest of public safety and in keeping with the event's child friendly appeal.

Ms Hocking said she sought advice from the health department and was told some e-cigarette juices can be harmful as they contain nicotine.

"Apparently the vapour [can have] a lot of nicotine in it and for the Royal Show it was about public health always, but also what it looks like and in particular for children," she said.

"A huge percentage of visitors to the Royal Show are families and little children and so we thought we'd bundle them [smokers] in the same place."

Callers into ABC 891 Adelaide asked Ms Hocking whether South Australia was over-policing such issues and becoming a "nanny state".

They asked whether the sale of alcohol and junk food at the show could also portray the wrong message to children.

But Ms Hocking said e-cigarettes were clearly different.

"You're consuming junk food, there's no third element of that like a vapour or smoke that is going to upset the person standing next to you, you're consuming that yourself," Ms Hocking said.

"We don't get complaints from other people saying the person next to me was eating a doughnut and now I'm fat.

"I think the majority of the public would accept that cigarettes are a little bit different to what people would say is junk food."

Ms Hocking said she was aware of other Adelaide venues also banning e-cigarettes.

Labor MP Annabel Digance is chairing a parliamentary committee in South Australia looking into the health risks associated with e-cigarettes.

The committee was formed in May and is consulting with various groups.

Ms Digance was supportive of the Royal Adelaide Show's decision to ask e-cigarette smokers to use designated smoking areas.

"The show has a duty of care to a wide demographic who will go through their gates over a week, so they need to make the best decision possible for all concerned and I get what they are doing," she said.

Ms Digance said there were still a lot of "unanswered questions" when it came to e-cigarettes.

She said while it was legal to possess nicotine juice for cigarettes, the distribution and sale of the nicotine juice was illegal.

"E-cigarettes are still such an unknown product," she said.