Kansas health officials confirmed the first death in the state Tuesday associated with an outbreak of serious lung disease related to vaping or using e-cigarettes. It is at least the sixth such death reported nationwide. The Kansas resident was over 50 and had a history of underlying health issues, state health officials said in a news release. The person was hospitalized “with symptoms that progressed rapidly.” Kansas officials said they do not have detailed information on what types of products were used by the patient.

The national investigation has not identified any specific vaping or e-cigarette products linked to all cases. Many patients report using vaping or e-cigarette products with liquids that contain cannabinoid products, such as THC, the active ingredient in marijuana that produces the high.

The Kansas death is at least the fourth reported in a middle aged or older person. Minnesota and Los Angeles county officials also reported deaths in older persons last week. The Minnesota patient was over 65 years old and died in August after a long and complicated hospitalization. Minnesota officials said the patient had a history of underlying lung disease, was hospitalized with a severe lung injury that progressed to include other conditions, and found the lung injury was associated with vaping illicit THC products.

Oregon health officials said last week that a middle-aged adult who died of a severe respiratory illness in late July had used an electronic cigarette containing marijuana oil from a legal dispensary. It was the first death tied to a vaping product bought at a pot shop. Illinois and Indiana reported deaths in adults but officials have not provided information about their ages or what type of products were used.

State and federal health authorities are focusing on the role of contaminants or counterfeit substances as a likely cause of vaping-related lung illnesses — now up to at least 450 possible cases in 33 states.

Officials are narrowing the possible culprits to adulterants in vaping products purported to have THC.

The sudden onset of these mysterious illnesses and the patients’ severe and distinctive symptoms have led investigators to focus on contaminants, rather than standard vaping products that have been in wide use for many years.

One potential lead is the oil derived from vitamin E, known as vitamin E acetate. Investigators at the U.S. Food and Drug Administration found the oil in cannabis products in samples collected from patients who fell ill across the United States. That same chemical was also found in nearly all cannabis samples from patients who fell ill in New York in recent weeks, a state health department spokeswoman said.

On Monday, New York state officials said they are issuing subpoenas to three companies the department has identified as selling “thickening agents” containing high levels of vitamin E that can be used in black market vaping products that contain THC. Dealers have been using thickening agents to dilute THC oil in street and illicit products, industry experts said.