What you say is so true, that's why I just try and have fun with it, saying things like:

"Man! Have you heard about this mercury stuff."

If they say no, I keep going:

"Geez! It's all over, in vaccines, silver fillings, and people are getting sick all over. It's amazing."

It really seems to get their attention, especially if they have silver fillings or if they've been vaccinated lately.