Wisconsin health officials also stated that patients reported using open tank systems and replaceable cartridge devices. Open systems allow users to prepare their own boiling liquids if they wish.
Dr. Emily Chapman, chief medical officer for the Minnesota Children's Hospital System, said he has treated four cases of acute, severe lung damage – including respiratory failure – in teens who have been vaping in the last month or so. Although hospital patients have shown improvement, Dr. Chapman said, it is unclear whether they will fully recover.
In addition, she noted that exploring teenage vamping patterns can be complicated.
Dr. Chapman also said she was concerned about what part of the public believed vaping was safe.
"The truth of the matter is that we have so little experience with vaping, compared to the experience we have with cigarettes and cigars. Remember how long it took us to understand that cigarettes are linked to lung cancer.
A recent study by Yale and Duke identified chemicals called acetals in some Juul e-cigarette liquids. These chemicals, according to the researchers, can be particularly irritating to the lungs and can cause damage by inhalation.
Jul does not agree with the findings of the study.
"The hypothetical analysis of researchers' exposure does not take into account real-world conditions, including realistic exposure of people to vapor products such as Juul," says Lindsay Andrews, a Juul spokesman.
Dry pods contain high levels of nicotine, which it can cause addiction and health problems. Some experts are worried about the effects of nicotine on the developing teenager's brain, and some studies suggest that nicotine intake can also affect the heart and arteries.