"That study and this new research are both consistent with the widely-held view that vaping is not without risk of cancer and other diseases, but that risk is usually considerably lower than smoking".
The researchers say that more work is needed to see whether vaping really does increase cancer rates.
The study was published in the Proceedings of the National Academy of Sciences in the U.S., just as MPs in the United Kingdom are holding an inquiry into the health effects of e-cigarettes to address gaps in research.
By the end of the trial, the smoke had caused DNA damage in the animal's lungs, bladders and hearts, as well as limiting lung proteins and important DNA fix.
The team exposed mice to e-cigarette smoke for three hours each day, five times a week for three months.
"It is therefore possible that E-cigarette smoke may contribute to lung and bladder cancer, as well as heart disease, in humans", the researchers wrote in their study, which was published in the journal PNAS on January 29.
Typically, an e-cigarette is filled with chemicals like propylene glycol, glycerine, nicotine, and flavorings such as menthol or mint.
Stats from the Centers of Disease Control and Prevention (CDC) say that previous year more than 7 percent of Chicago high schoolers reported using cigars, and more than 6.5 percent said they vaped or used e-cigarettes. The chemists wrote that the damage caused by vaping increased as a person took more puffs of an e-cigarette.
"The results suggest that whilst some people switch from smoking to vaping quickly and completely, others have a longer transition". Their organs were likewise less able to fix DNA.
The study was carried out by testing the effects of e-cigarette vapours on healthy mice and human cells, which means further studies will be required in order to determine if e-cigarettes can harm human organs similarly. Another experiment found the exact same pattern in human lung and bladder cells exposed to nicotine and a chemical it gets broken down into, nicotine-derived nitrosamine ketone. The report found vaping was likely to be less harmful than conventional cigarettes.
The report also said that the potential dangers and benefits of vaping e-cigarettes may depend on the user's age.
It's the first evidence we have that nicotine can be carcinogenic in and of itself, said Dr Roy Herbst, chief of medical oncology at Yale Cancer Centre, and chair of the American Association for Cancer Research's Tobacco and Cancer sub-committee.
While tobacco smoke contains a host of potentially risky chemicals, e-cigarette vapour consists only of nicotine and some relatively harmless organic solvents.