I didn't know nicotine was a carcinogen as is stated in that article, I'm pretty certain it is NOT. I'm also pretty certain there are no other carcinogens in plain ejuice, that being nicotine with pg and vg. How he can state anything is beyond me when he points out that "no studies have been done" to support anything he claims!
Nicotine is definitely not a carcinogen. The pharmaceutical grade nicotine that is used in NRT products (patch, gum, lozenge, Rx inhaler, and nasal spray) is identical to the pharmaceutical grade nicotine used in e-cigarette liquid. Pharmaceutical grade nicotine is extracted from tobacco, and therefore may contain harmless traces of Tobacco-specific Nitrosamines (TSNAs).
In 2009 when the FDA issued their infamous press release about testing 18 samples from two brands of e-cigarettes*, the gifted spin-doctor Dr. Joshua Shafstein focused on the idea that e-cigarettes contain carcinogens, leaving out the very pertinent fact that the quantity FDA detected was no higher than that found in nicotine patches and gum.
There are no cancer warnings on FDA-approved nicotine products because there has never been a case of cancer linked to use of those products. So if 8 nanograms of TSNAs in a patch doesn't cause cancer, why would an identical 8 nanograms of TSNAs in e-liquid cause cancer? The answer is, it wouldn't.
Smokeless tobacco (ST) products contain much higher concentrations of TSNAs than 8 ng, yet nicotine toxicology expert Dr. Neal Benowitcz testified at a 2010 FDA hearing "The lack of increase in common cancers in lifelong ST users indicates that nicotine is not a general cancer promoter."
http://www.fda.gov/downloads/Drugs/NewsEvents/UCM232147.pdf
*Despite the fact that there were dozens, if not hundreds, of companies selling e-cigarettes, the FDA chose to test only samples from the same two companies that a few months earlier had filed a suit against FDA product seizures in the U.S. District Court for the District of Columbia. Merely a coincidence? Yeah, right!
For more information see CASAA's e-cigarette history:
E-cigarette History