I found a review in Science and checked out The Drunken Botanist, the Plants that Create the World's Great Drinks by Amy Stewart http://www.amazon.com/The-Drunken-Botanist-Plants-Create/dp/1616200464/ref=sr_1_1?ie=UTF8&qid=1378216580&sr=8-1&keywords=the+drunken+botanist. It's fun, a cheap chance to learn more botany and good stories (know how the alcohol content measure "proof" came about?)
Coincidentally, G and I went to the Scotch tasting at the Scottish Games Sunday. G was chatting up one of the Scotch vendors, and I happened to mention the above book to him when said vendor mentioned gin botanicals. His eyebrows shot up and he said juniper was poisonous. I said not in the quantities ingested in gin. He said true, but the botanical is never metabolized, so over a lifetime of drinking gin, it accumulates. Of course, that got my attention. I searched MedLine, the FDA Poisonous Plant list, and some other trusted sources this morning. With all the lore out there on herbaceous bioactivity, this was not a time to turn to Wikipedia.
There are 60 species of Juniperus; the one used for gin flavoring most widely is J. communis communius. Three examples of toxic species are J. ashei, J. sabina, and J. pinchotii. The latter have much more sabinene and sabinyl acetate among the many terpenes in the leaves and berries. Those are the compounds responsible for the unwanted reproductive and kidney effects. I could find no reference in Medline indicating that any of the terpenes bioaccumulate. So I don't have to give up my gin after all.