Number of people killed

Among a group of 1,043 patients for whom there was data on sex and age, 70 percent were male while 80 percent were under 35.

More than three-quarters of those sickened used tetrahydrocannabinol (THC), the primary psychoactive substance of marijuana, with or without nicotine products.

A report by clinicians in North Carolina last month pointed to the inhalation of fatty substances from aerosolized oils, but a new study by the Mayo Clinic published this week found patients´ lungs had been exposed to noxious fumes.E-cigarettes have been available in the US since 2006, and it is not clear whether the outbreak is only happening now -- or if there were cases earlier that were wrongly diagnosed.

Initially conceived as a smoking cessation device, e-cigarette use has skyrocketed among teens, with preliminary official data for 2019 showing more than a quarter of high school students using e-cigarettes in the past 30 days.

They were until recently perceived as a less harmful alternative to smoking because they do not contain the 7,000 chemicals in cigarettes,