Why were cell culture and animal experiments not included in the review?
Exposure in vitro (laboratory studies) is very different to those in vivo (real life situations). In cell culture experiments cells are exposed directly to a fluoride solution containing highly reactive unbound anions. This is very different to exposure in the body where fluoride anions have to first be absorbed through a selective barrier in the gut. Once in the body it is unlikely that many of the anions will be in a free state, their reactive nature means that they bind very readily to other molecules rendering them inactive. It is the binding of fluoride to these molecules, the ratio of free to bound anions and the way in which these agents interact with other sites in the body that should be investigated, this can only be done in vivo systems. Similarly exposure in animals may be very different from exposure in humans. Effects seen in animals may not be seen in humans, and where these effects may occur in humans it is very difficult to know at what level such effects will occur –
