The Centre for Disease Control and Prevention in the US has found the possible reason for 2000 vaping injuries.
Fluid samples of the lungs of patients with e-cig or vaping product use associated lung injury identified vitamin E acetate which is an additive in some THC-products.
Lab tests show 29 patients from 10 states has vitamin E acetate in all fluid samples, THC was identified in 82% of the samples and nicotine in 62% of the samples.
THC is the chemical in the class B drug cannabis that gets someone stoned.
In summary, they found the majority of vaping injuries have been caused by someone vaping a THC product, and as the department claims most of the injuries are caused also by people buying unofficial untested vaping products on the street or bought elsewhere.
Scientists have found the cause of the injuries as vitamin E acetate have though said more research is needed as other chemicals could be causing problems, it is widely regarded though as a step in the right direction.
Here in the UK the government are keeping an eye on things and will wait and see what the US comes up with before making any decision.