The composition of cat litter depends on whether it is clay-based or clumping. Clay-based cat litter is made of an absorbent, granulated clay, while clumping or scoopable litter is made of bentonite and silica. Greener, more eco-friendly options include wheat, sawdust, pine and cedar chips, newspaper and baking soda.
Before Edward Lowe invented cat litter in 1947, cat owners used sand or furnace ashes for their indoor pets, but these ingredients proved to be messy. Lowe used his father's industrial absorbents to create cat litter, selling it in a local pet store, and eventually creating the Tidy Cats brand. During the 1980s, Thomas Nelson discovered that bentonite clumped, allowing pet owners to scoop out cat litter rather than throwing out the entire box. Silica was later added to aid the clumping. Clumping cat litter is more environmentally friendly than clay litter because it creates less waste and requires less work from the pet owner.
Clumping cat litter is relatively safe, only proving harmful to pets when ingested in large quantities. Dogs and kittens are at the most risk for gastrointestinal harm. However, some pet owners concerned with the amount of chemicals prefer pine and cedar chips, which are natural odor absorbents, or they create their own cat litter out of various materials.