The U.S. Centers for Disease Control and Prevention is investigating a growing number of “severe” lung disease cases that appear to be related to vaping.
Since late June, according to the CDC, 94 people in 14 states have come down with serious lung illnesses that may be linked to use of e-cigarettes, which heat substances including nicotine and cannabis to create aerosols that users inhale. The case count has grown high enough to prompt the CDC to work with state health departments to learn more about what could be causing the worrisome conditions, which are primarily affecting adolescents.
Although “more information is needed to determine what is causing the illnesses,” according to the CDC, vaping appears to be a common thread across states involved in the investigation, including Illinois, California, Indiana, Minnesota and Wisconsin, where nearly a third of reported cases have originated. Wisconsin state health officials say both pediatric and adult patients are exhibiting symptoms including shortness of breath, fatigue, chest pain, cough and weight loss. Many patients reported vaping in the weeks or months before hospitalization, according to the state health department. It’s unclear which e-cigarette products they had used, and they may have consumed substances including nicotine, THC and/or synthetic cannabinoids (a category that includes the drug K2), according to health officials.
A CDC representative did not immediately respond to TIME’s inquiry about common symptoms, substance use or preexisting conditions across cases. The agency said in its statement that an infectious disease does not appear to be behind the illnesses.
Vaping nicotine is thought to be a healthier long-term alternative to smoking cigarettes, since it delivers fewer cancer-causing chemicals than traditional combustible products. But as e-cigarette use has grown more popular among both adults, for whom it is intended, and teenagers, for whom it is illegal, a number of apparent side effects have been reported. Preliminary studies have shown links between e-cigarette use and vascular, respiratory and cellular damage, and federal health agencies are looking into rare health issues potentially associated with vaping, such as seizures, injuries resulting from exploding devices—and, now, pulmonary diseases. Some teenagers have also become addicted to nicotine by vaping, raising concerns among public-health officials.
It’s not entirely clear how or if e-cigarettes are causing many of these health problems. But nicotine poisoning can occur when people, especially children, ingest liquid nicotine or absorb it through the skin, according to the American Academy of Pediatrics. Vaping products are also not regulated by the Food and Drug Administration (FDA), so safety and manufacturing practices may be lacking at some companies. In 2018, for example, the FDA warned that products from a Chinese e-cigarette company contained unapproved drugs intended for erectile dysfunction, which could be dangerous for certain users.
People who vape non-nicotine substances—such as K2, which has previously been tied to large-scale overdoses—may also be at risk of health problems.