Well, consuming straight nicotine is a brand new phenom, and science is racing to catch up. Give it 10 years for any definitive science to be peer reviewed, confirmed, and then generally accepted. Take a look at things like this: http://www.webmd.com/cancer/news/20060720/nicotine-speeds-lu...

I can't find my original sources, so please, take my personal theories with a grain of salt... Many years ago I was studying the types of cancer smokers are more likely to get other than lung cancer. After my uncontrollable urge to crunch numbers, I came up with 2/3 lung cancer, 1/3 other cancer and made an unscientific guess that nicotine plays a big part in the non-lung cancer related illness.