The Centers for Disease Control and Prevention Director Robert Redfield has been invited to testify before a House panel at a hearing about the “outbreak of lung illnesses associated with using e-cigarette products,” according to a Tuesday letter obtained by The Daily Beast. The hearing with the House Oversight’s Subcommittee on Economic and Consumer Policy is slated to take place on Sept. 24.

On Tuesday, the state of Kansas confirmed a sixth death linked to a vaping-related illness that has affected people nationwide. According to NBC News, the other five vaping-related deaths occurred in Illinois, Indiana, Oregon, Minnesota, and California. The CDC said it’s been investigating the outbreak of “severe pulmonary disease” associated with e-cigarettes, and stated last week that there are 450 potential lung illness cases across the U.S.

In a statement, subcommittee Chairman Raja Krishnamoorthi said he asked Redfield to testify about the warning the CDC issued against using e-cigarettes until “more conclusive evidence of the cause of these illnesses” was found.

“I look forward to learning from our nation’s preeminent public health institution on the potential causes of this outbreak and what must be done to end it,” Krishnamoorthi said. The CDC did not respond to requests for comment.