Hello.

Is there any chemist or medical specialist out there who is willing to
comment on the following issue, regarding a debate about the
effectiveness of bongs (water pipes) to filter out potentially harmful
ingredients from smoke.

On this webpage you can find a comparison between the composition of
tobacco and marijuana smoke, listing the ingredients in both:
http://www.erowid.org/plants/cannabis/cannabis_info3.shtml

I don't smoke regularly myself, nor do I condone of smoking anything
(whether it's marijuana or tobacco). I am interested in this issue
however because I think that when you are engaged in some potentially
harmful activity, it's still best to minimize potential health-risks as
much as possible.

What are the primary nasty (in terms of health risk) ingredients in
smoke and to what extend are they likely to be filtered out by water
used for filtration in a smoking device?

There are studies that suggest that a bong is counterproductive because
it  affects the tar-THC ratio adversely:

http://www.maps.org/news-letters/v06n3/06359mj1.html

Is this the only possible consideration or are there other potentially
harmful ingredients, besides tar, found in smoke that might be filtered
by passing smoke through water?

Perhaps someone could point out the most likely place to find the
solubility in water of the primary ingredients in smoke?
Some medical advice on which ingredients in smoke are most likely to be
detrimental to the respiratory system would also be appreciated.

thanks very much for any comments or suggestions, kind regards, Niek