[Brandye]

I do not know which is "best." Water based are the old standbys and I have never heard of anyone having a reaction to them. Silicone certainly lasts longer. As long as there is any trace left, it will help. My problem with those is that those traces may last a very long time and it is not stuff that I really want in my when water is an alternative.

I do not allow anal penetration and so do not worry about his. The studies you cite are nice little academic exercises but whether or not there is any practical advice that can be inferred is another question.

If you are this concerned about the dangers of one lube vs another, why allow penile penetration of your anus? This is more damaging than any common lube.