Rechargeable and disposable batteries both include toxins. Mercury, cadmium and sulfuric acid (in car batteries) can be harmful if they are simply dumped in the waste bin. Many Best Buy, Office Depot and Staples locations accept rechargeable batteries for recycling. Single-use batteries may be a bit more tricky to recycle. Try mailing batteries to EcoLights for safe recycling (there may be a fee to do so).