Dear Earth Talk:What are the health effects of clumping cat litter on humans? Are there any negative side effects from breathing the actual litter? —Andy and Taeja Klukas, Maple Grove, MN
Clay-based cat litters contain crystalline silica, the main component in sand, rock and mineral ores. A possible health threat from clay-based litters is posed by silica dust, which can be kicked up and breathed in by both cats and humans.