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Mysterious lung injuries have killed at least 33 e-cigarette users and sickened nearly 1,500. The Centers for Disease Control and Prevention is digging deeper to find the exact cause. NPR science correspondent Richard Harris traveled to Atlanta to learn about the latest twists in their investigation.
RICHARD HARRIS, BYLINE: The calming sound of a fountain echoes between two laboratories on the CDC's Chamblee campus, but it's fair to say that for many scientists working on vaping injuries at the federal health agency, the mood is not so serene. I'm told that in one of these laboratory buildings, they've actually started testing fluid that had been taken from the lungs of people who had been exposed to vaping products and ended up with severe lung disease. That's a new step in the investigation, which has now swollen to include more than 140 CDC scientists and staff. The lab buildings are off-limits to most visitors, so on a visit Friday, I am guided instead into an adjoining building to meet the man who's overseeing the labs.
Hey. Richard Harris.
JIM PIRKLE: Jim Pirkle. Nice to meet you.
HARRIS: Nice to meet you.
PIRKLE: Yeah. Come on in. Have a seat.
HARRIS: Dr. Pirkle has seen many investigations in his time. Best case, there's a straight line from a health problem to the cause. Vaping lung disease, well, that's a different story.
PIRKLE: There wasn't something that just stood out in everything that closed the case and said, we know exactly what it is.
HARRIS: Pirkle realized early on that his labs, which started out studying the toxic chemicals in cigarettes, could be brought to bear for this mystery.
PIRKLE: We have 13 smoking machines, and we're smoking cigarettes and e-cigarettes all the time - maybe not what you're classically thinking CDC is doing.
HARRIS: Elsewhere, the Food and Drug Administration labs have been studying the vaping fluid from suspicious products, but people don't just breathe that stuff in. E-cigarettes vaporize those components by heating them up.
PIRKLE: So after you've heated the fluid, it's possible you've made something else that's dangerous.
HARRIS: Pirkle shows me some components of the testing equipment.
PIRKLE: We have a pad here that'll collect the aerosol and all the lipid-like substances, and then the stuff that goes through as gases - that is trapped on another trap. And so it's just - it's like a super filter right there.
HARRIS: Pirkle says they'll compare what they find from the devices to what's in the lungs of patients who fell ill. The first fluid samples from vapers' lungs are just now being analyzed at the CDC.
PIRKLE: So that gives us kind of a sampling of what's on the inside surface of the lung, and that's actually very important because we think that's where the problem is. It's when things go in and get in contact with that inside surface of the lung.
HARRIS: One item on that list is to look for oils which have been observed in some samples. They're also measuring natural compounds called terpenes that, among other things, contribute to the pungent flavor of THC extracted from marijuana - yes, terpenes as in turpentine. In all, they're planning to run about a dozen tests on each vape and lung fluid sample, Pirkle says.
PIRKLE: It took a while to get all those methods developed, all that interpretation stuff figured out. But it started this morning, so we're chugging on it. We're out at 60 miles an hour.
HARRIS: Discoveries in this lab will get relayed back to Dr. Ram Koppaka, a lung specialist who got tapped to join the CDC's vaping investigation team.
RAM KOPPAKA: From the beginning, the approach has been to entertain all potential theories.
HARRIS: And it's often tricky to sort out cause and effect. For example, is oily material seen in some lung samples causing the problem or part of the body's reaction? What about the signs of direct chemical damage in victim's lungs? Koppaka is hoping the labs will provide answers. That can help guide treatment, but it is also urgently needed so doctors can know exactly what to look for to diagnose this condition.
KOPPAKA: We don't have that yet. Certainly, if the cause or causes of the lung injury are identified, that would advance that effort a great deal because there might be a way to detect them in the lungs or in the blood or in the tissues or whatever. But we're not there yet.
HARRIS: The consensus around the CDC team, though, is that they are heading in the right direction.
Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.