An Oireachtas committee has heard that over-regulation of vaping would be "detrimental to public health" and would risk driving people back onto cigarettes.
But deputies responded with concern that children are being deliberately targeted by flavoured brands.
The Joint Committee on Health is continuing its scrutiny of the Public Health (Tobacco and Nicotine Inhaling Products) Bill.
"We have no interest beyond helping adult Irish smokers to quit smoking," the head of the Irish Vape Vendors Association (IVVA) claimed.
"Most of our customers no longer smoke," Director Declan Connolly said, but later accepted that this was based on "anecdotal" evidence.
Several deputies pointed to an absence of any research demonstrating that vaping helps smokers to quit.
Mr Connolly accepted that vaping is "not a panacea" but insisted that it has "a very important role to play" in helping smokers to kick the habit.
"Nothing is better than fresh air," he acknowledged, but faced strong criticism from Green Party Deputy Nessa Hourigan for the flavoured brands which he sells on his website.
Deputy Hourigan said that one product came in "an incredibly cute little bottle".
The "strawberry milkshake" flavoured product bore a cartoon character like something you would see "on children's lollypops", she said.
Deputy Hourigan also referred to research published in the British Medical Journal which indicates that smokers seeking to quit do better with aids such as nicotine replacement therapy, rather than vaping.
Mr Connolly said that the 2019 Healthy Ireland report which showed that 38% of people who had tried to quit smoking had used vaping.
But the IVVA accepted that the websites its members operate can not ensure that customers are aged over eighteen.
Fine Gael TD Colm Burke said that the committee heard in 2019 that well over a third of teenagers said that they had vaped, up from under a quarter of them in 2015.
The Irish Heart Foundation and Irish Cancer Society had also warned the committee that teenagers who vape are three times more likely to end up smoking.
That is "not born out by the facts", Mr Connolly countered, saying that there are different ways to view the figures, which are drawn from the European School Survey Project on Alcohol and Other Drugs.
Those admitting to "use during the previous thirty days" had risen substantially, but he argued that this "is not a very good indicator".
The slight increase in the figures for "daily usage" should be used, he said.
The committee heard that there are 700,000 smokers in Ireland and 200,000 e-cigarette users.
Mr Connolly said he would support over 18s legislation, a licencing scheme "if it is proportionate" and "fair", strict advertising rules and a ban on vending machines.
But he pushed back against any suggestion that flavours should be banned, telling the committee that nearly two thirds of users choose those products.
Sinn Féin's David Cullinane quoted a Health Research Board finding that teenagers who use e-cigarettes are up to five times more likely to start smoking.
Another report pointed to "consistent evidence that flavours attract youths to e-cigarettes", he said.
Mr Connolly accepted that "flavours are attractive", but said that many factors push people to vape, noting that those who do are "generally from poorer, working-class backgrounds".
Fianna Fáil TD John Lahart noted that vaping products are "very seductively packaged" as cigarettes once were.
Joan O'Connell, a board member of the IVVA, accepted that some packaging is "overly colourful".
"I would have no problem increasing the age to 21," she said.
