Hi Janette, I have used Glue Dots, when I could get them to stick, Millcreeks stickems (not sure what they are called:o ) and Silicone. I have purposely burnt my containers clear to the bottom until the candle actually goes out b/c there is no wick left to burn and have not noticed a difference in scent or soot. I use high temp glue and the tabs stay put, so far...As far as toxicity is concerned I can't answer that one. You need to ask someone that has more smart pills than I do. Hth and good luck with your venture.