In what is believed to be the first death from a vaping pen explosion in the United States, 38-year-old Tallmadge D'Elia died when two pieces of the e-cigarette lodged themselves in his cranium, the Pinellas County medical examiner said.
D'Elia was discovered when firefighters broke into the burning apartment in St Petersburg, Florida, on May 5
The fire was found to have been caused by the exploding device, and resulted in 80 percent burns to his body.
The lethal vaping device was identified as a Smok-E Mountain brand, which is manufactured in the Philippines, according to the local Tampa Bay Times newspaper.
It said the device was known as a "mechanical mod" e-cigarette, which lacks some of the safety features that other makes have, including computer chips to prevent them from overheating.
"A regulated device typically contains electronic circuitry, built-in safety features, and adjustable power settings," Gregory Conley, president of the American Vaping Association, told AFP.
"In contrast, a mechanical mod is unregulated and works simply by drawing the power of a battery to an atomizer," he said.
"If the battery in a mechanical mod over-discharges and the device doesn't contain enough air holes to allow the battery to vent, there is a risk of explosion."
The coroner's report did not specify what made the vape pen explode.
The Smok-E Mountain brand's Facebook page had been taken down on Thursday.
According to FEMA, the Federal Emergency Management Agency, there were 195 fires and explosions involving electronic cigarettes between 2009 and 2016 in the United States.
None of them was fatal, although a fire safety officer who studied the cases told the Tampa Bay Times they could result in "horrific injuries" to the face, and to the thigh and groin area if they exploded in users' pockets.
The Food and Drug Administration warns that the devices can explode and cause severe injuries, noting that while the exact causes of such incidents remains unsolved, they appear to be mostly linked to lithium-ion batteries, which are also used in cell phones.
The Centers for Disease Control and Prevention has said that "e-cigarettes have the potential to benefit adult smokers who are not pregnant if used as a complete substitute for regular cigarettes and other smoked tobacco products."
However, a study carried out on mice, and reported in the National Academy of Sciences' publication PNAS in January, showed that vaping can increase the risk of certain types of cancer and heart disease.
