E-cigarettes can cause cancer even when they are nicotine-free, scientists have claimed. The research suggests that there might be little difference health-wise between using the electronic pens and smoking regular cigarettes.Lab experiments on the battery operated devices found they lead to the same kind of cell damage that triggers the disease. The finding adds to growing evidence electronic cigarettes may cause serious health problems because of the toxins they contain.In the study scientists tested two popular brands and showed they harmed cells in ways that could spark the development of a tumor even with no nicotine, the addictive ingredient in tobacco.Writing in the journal Oral Oncology, they said: “Our study strongly suggests electronic cigarettes are not as safe as their marketing makes them appear to the public.”Although some countries have banned e-cigs their use and sale in the UK, like the US, are legal.But the US Food and Drug Administration does not regulate e-cigarettes and has warned of possible health risks, although evidence is limited as they have just been readily available for less than a decade.Professor Jessica Wang-Rodriquez, of the University of California, San Diego, said: “There haven’t been many good lab studies on the effects of these products on actual human cells.”The head and neck cancer specialist and colleagues at the Veterans Affairs San Diego Healthcare System created an extract from the vapour of the products and used it to treat human cells in petri dishes.These were more likely to suffer DNA damage and die, compared with untreated cells. In particular the exposed cells showed tell tale ‘strand breaks’ in the familiar double helix of molecules that intertwine.When one or both break apart and the cellular repair process does not work properly, the stage is set for cancer. The affected cells were also more likely to launch into programmed cell death or cell injury, known as apoptosis and necrosis respectively.In the main part of the study the researchers used normal epithelial cells which line organs, glands, and cavities throughout the body, including the mouth and lungs, and found while nicotine caused worse damage, vapor that was free of the chemical was enough to alter them.