We have chosen to use silicone beads rather than rubber or some other synthetic material because of the safety and durability of the silicone used in these products. As you can see on our Safety page (information comes from our supplier), the silicone beads and rings are non-toxic and made of 100% food grade silicone. They are BPA free, as well as free of lead, cadmium, PVC, mercury and phthalates. They are also FDA, LFGB, and SGS approved.