Scott - As far as I'm aware, there is no risk involved at all with using the tablets. They seem to be a 'gentle' method of removing grime & particularly lime-scale/water-marks inside of vases and decanters for example. The true beauty of using them, is that they can be simply used to do their thing overnight, and provided you only use hot water (appropriately temperature to suit to the glass piece itself) then all is well! It is a relatively low cost method too, whilst also not being labour intensive... Give it a go! You may be pleasantly surprised with the results. I've even used them on delicate free-blown Victorian vases without causing any detriment. I guess that if they are good enough for teeth, then they are good enough for glass too! They work wonders inside glass vacuum flasks, removing unpleasant odours whilst also disinfecting them cleanly and safely.