Inside a battery, the chemical reaction that takes place produces energy, which is converted into electricity. Most cylinder and button batteries contain toxic metals such as cadmium, mercury, lead, and nickel, which are extremely harmful to the environment. Even though newer batteries may be disposed of in the trash, it is strongly recommended that you recycle your alkaline batteries.
Many large commercial stores accept batteries for recycling. They may not advertise this fact, so it is a matter of asking the manager. Try to limit the number of products you use that require batteries, and buy a battery charger and rechargeable batteries.
-Abrams, “365 Ways To Save The Earth”, 2008