Rounded Nylon bristles (SOFT) for superior cleaning. Ergonomic handle made from 100% Corn Starch (Non GMO!). Typically takes 90 days to break down in a commercial compost. You have made the right choice - any way you dispose of this, you can be sure that these toothbrushes will not be land-fill for millions of years to come - unlike many toothbrushes in use today.