Researchers are working hard to determine the cause of more than 500 cases of lung illness affecting e-cigarette users. Eight of those people have died, sparking a criminal investigation from the FDA – but even before this outbreak, e-cigarettes divided the medical community. The American Lung Association has said that "e-cigarettes are not safe," but the American Cancer Society said they're "likely to be significantly less harmful for adults than smoking regular cigarettes."



One of the web's most talked-about pro-vaping videos is an experiment comparing the effects of tobacco cigarettes and e-cigarettes on the lungs, put out by England's top public health agency.



"My research shows that e-cigarettes are significantly less harmful than cigarettes," said Dr. Lion Shahab, an associate professor at University College London.

Public Health England describes e-cigarettes as "at least 95% less harmful" than tobacco cigarettes.

Dr. David Abrams, a professor at New York University, said that he thinks that's a fair estimate. "Actually, I would go further," he said. "I think there's no evidence from looking at the cancer biomarkers, that it could be as high as 98% or 99% for cancer."

Abrams said he's worried that the panic over e-cigarette-linked illnesses will distract from the public health benefits they could offer.

"I think we've forgotten that 120 years ago, the disruptive technology was the cigarette rolling machine that literally caused this epidemic of lung cancer and other diseases. And now we have an opportunity 120 years later to get rid of the cigarette with a new technology that delivers nicotine in a very satisfying way without the major harms of burning tobacco," he said. "If we lose this opportunity, I think we will have blown the single biggest public health opportunity we've ever had in 120 years to get rid of cigarettes and replace them with a much safer form of nicotine for everybody."



To parse the competing claims, "CBS This Morning" asked Abrams' colleagues in the school of medicine to recreate the experiment by Public Health England.

"This is gonna look very yucky," NYU School of Medicine professor Terry Gordon told "CBS This Morning" co-host Tony Dokoupil. "You're gonna see lots of brown and dark color, and that's what's gonna simulate what goes in the lungs of people."

For about two hours, the NYU team simulated smoking four packs of cigarettes, and compared it to the same amount of vaping. The differences were plain to see: The damage caused by cigarette smoke was obvious; the vapor from a coffee-flavored e-liquid, not so much.

Tony Dokoupil compares the effects of e-cigarettes and traditional cigarettes CBS News

Gordon also thinks Public Health England's estimate is "fairly accurate." "Might be 80%-90%. I don't know how they can be that accurate," she said. "But … they're much safer than cigarettes."

But other American scientists, like West Virginia University School of Medicine associate professor Mark Olfert, are drawing very different conclusions.

"I would say it's 95% harmful," Olfert said, "because … in any single study that I've seen that's looking at this in a meaningful way outside the lung, they're finding damage and harm."

Inside a lab at West Virginia University, Olfert investigates vaping's potential long-term effects on the heart by exposing rodents to e-cigarette vapor.

In a recent study, Olfert looked at eight months of exposure -- the equivalent of 25 human years. What he found concerns him: The animals' arteries stiffened almost as much as those exposed to cigarette smoke over the same time.

"Stiffer arteries means greater risk for stroke, for heart attack, atherosclerosis, aneurisms, any number of vascular effects," Olfert said. "It's extremely alarming, because it tells me that e-cigarettes simply are not gonna be safer than cigarettes."

Olfert studies the effects of e-cigarette vapor on rodents CBS News

Now, he's trying to figure out why that happens. He said it's not the nicotine.

"It's something in the base solution," he said. "The base solution is made up of propylene glycol and vegetable glycerin. These are oils. Petroleum."

In response to the argument that e-cigarettes are just oil and water vapor, Olfert said "that's actually the biggest lie about e-cigarettes, is that it's water vapor. That's an oil and petroleum solution."

The CDC is now advising people worried about health risks to avoid vaping, but said that anyone using e-cigarettes who quit smoking shouldn't go back to cigarettes. The FDA's official deadline for e-cigarette manufacturers to demonstrate they are a "net good" to public health is May 2020.

Abrams, however, doesn't believe the sudden outbreak of illnesses should stop adults from vaping. "I think all the evidence we've seen from the FDA and the CDC reports is that these cases are people who bought marijuana oils on the street made either illegally or in a sort of a street version like a dirty street drug," he said.

"We haven't seen a single case that a commercially made legitimate e-cigarette that smokers are using has caused any of these illnesses," Abrams added. "And I would say for smokers they should not be scared by what they're seeing and that e-cigarettes should still be used instead of cigarettes if they've already switched."

Meanwhile, a bipartisan group in Congress is working with parents to keep teenagers away from e-cigarettes, while accusing the vaping industry of marketing to kids.

"It's frankly unfortunate that it takes so many people to get sick and even die across this country before we really pay the kind of attention that we should," said Representative Diana DeGette, a Democrat from Colorado.

"We will not allow our children to be used as human guinea pigs," added Meredith Berkman, co-founder of Parents Against Vaping E-Cigarettes.

Like the Trump administration, they say flavors marketed to teenagers is part of the problem. Data from 2018 shows that more than 20% of high school students used e-cigarettes, up 78% from 2017. Almost 70% of those students used flavored e-cigarettes.

Juul has said in the past that it has never marketed the product to youths. The vaping industry is reportedly already lobbying to create an exemption for mint and menthol, two of the most popular flavors used by teenagers, in the Trump administration's flavor ban. The congressional caucus will have its first major hearing on the issue next week.