Using a new method of testing, researchers found that in three out of the ten e-cigs studied, the level of formaldehyde, a known carcinogen, came close to the amount in conventional cigarettes. Furthermore, a highly toxic molecule called acrolein was detected "sometimes at levels even higher than in traditional cigarettes," said Thomas Laurenceau, chief editor of the magazine.
Do e-cigarettes cause cancer? - The Week
to my knowledge formaldehyde couldnt get there unless you actively put it there
makes no sense