“The urgent issue,” he said, “is that millions of people are dying from tobacco products already on the market.”

Down the street from the convention center, at the N’vY Hotel, Philip Morris International was trying to reinforce that message to anyone venturing into its Science Hub, with a touch screen that told the company’s story of moving into the harm-reduction business. Plates of colorful macarons were positioned at the entry.

Moira Gilchrist, a vice president of Philip Morris International, said the company was trying to promote the business’s new policy of transparency to the delegates and anyone else at the meeting.

“Anyone who is interested in alternatives to cigarettes that can be offered to the world’s billion smokers is invited here to see the science we have, which we believe is really promising,” Ms. Gilchrist said. “Part of why we are here today is encouraging policymakers not to treat every single tobacco product as the same.”

Addressing lingering suspicions about the role of Big Tobacco, Ms. Gilchrist said: “We are absolutely not asking people to believe us. We’re asking people to replicate our science, to review our science and come to their own conclusions.”

“We’re not asking for forgiveness,” she added.

But many delegates interviewed at the convention remained wary of electronic nicotine delivery devices, and as the session wrapped up on Saturday, they approved a directive affirming that heat-not-burn products should continue to be subject to the same restrictions as other tobacco products, like cigarettes. They declined to offer an endorsement or special treatment to any alternate nicotine delivery systems.

“It’s not a victory for vaping,” said Matthew L. Myers, president of Campaign for Tobacco-Free Kids, who took part in the long debate Thursday night. “They would like to be treated differently in every respect.”

So the debate will continue.

“We believe there is room for these alternative products and believe it has to be well studied and well investigated,” said Dr. Ghazi Zaatari, a delegate and medical school professor in Lebanon, who oversaw some of the conference’s research. “We have been fooled before.”