The study the TGA refers to was conducted by the American FDA and announced via Press Release in July 2009. The problem is they left out some important information.
A day’s supply of liquid contains no more nitrosamines (“carcinogens”) than FDA-approved nicotine products. Although the FDA characterized diethylene glycol (DEG) as antifreeze, actually DEG is a chemical used to keep tobacco moist.
The quantity detected was well below toxic levels.
In short, the FDA did not find harmful quantities of any substance.