Many mass market cat litters contain significant amounts of silica dust which has been linked to upper respiratory issues in cats and even humans. Likewise, the chemical fragrances in many cat litters can also be toxic to cats.
Frugal eco-conscious cat owners might consider making their own cat litter by repurposing everyday materials that would otherwise end up in the waste stream. Plain sawdust makes great cat litter, but doesn't control odor as well as other substrates and might be hard to find in urban areas. The website treehugger.com offers instructions on how to turn old newspapers into cat litter; the process is a bit involved but can save money while extending the life of discarded newsprint.
Is sawdust good for cat litter? Wood shavings and sawdust also make good cat litter substrates.
NEPCO's Cedarific Natural Cat Litter is a blend of hardwood and cedar chips with no clay or silica dust. Besides being inexpensive, it is easy to handle, has a pleasant odor, and is biodegradable and compostable.