An ongoing Food and Drug Administration investigation into a possible link between seizures and e-cigarette use was kicked off by three cases allegedly involving Juul use, Bloomberg reported today.

“No proof of causality, but at a minimum, an association with Juul.”

Bloomberg obtained communications between FDA officials in mid-October 2018, which detailed the three cases. The FDA found “no proof of causality, but at a minimum, an association with Juul,” Mitch Zeller, the director of the FDA’s Center for Tobacco Products, wrote to Scott Gottlieb, the FDA commissioner at the time. In an interview, Zeller said that the FDA had not been able to confirm that Juul use was associated with the seizures in two of the three initially reported cases, according to Bloomberg.

“We are aware of their initial report that found 32 cases tied to vapor products over 10 years, some of which referenced JUUL products by the submitter,” a Juul spokesperson said in an emailed statement to The Verge. “While FDA has not reached out to us about this issue, we will vigilantly monitor for any evidence of potential safety issues and work cooperatively as we continue to combat youth usage and eliminate cigarettes, the number one cause of preventable death in the world.”

Over the next several months, the agency uncovered an additional 32 reports of e-cigarette use that had been linked to seizures between 2010 and 2019. In April, it publicly announced its investigation. Since then, the total number of reports to the FDA associating e-cigarette use with seizures has increased to 127. The FDA continues to investigate reports of seizures through its Safety Reporting Portal.

Separately, the Centers for Disease Control and Prevention is investigating an unknown lung disease that also seems to be associated with e-cigarette use. More than 190 people have the unknown illness. Last week, one person died after being hospitalized with the disease.

Yesterday, USA Today published an article pointing the finger at marijuana vapes for the lung disease. Juul is quoted in it. “Many patients were vaping both nicotine and THC,” Juul told USA Today in a statement. “We also must ensure illegal products, such as counterfeit, copycat, and those that deliver controlled substances, stay out of the market.”