The Risk Profile of E-Cigarettes is an excellent article to back up a letter - it's useful to have something to support us.
If you are writing specifically about the EU hearing in five days time - you couldn't get better than - Clive Bates (former director of ASH) Medicines regulation for e-cigarettes – when caution can kill
I have spent loads of time replying to my replies and sending extra links for my respondees to research with. I have had good, bad and indifferent responses.
Still working at it.