I had never heard of that but apparently it is quite an issue. I found this article on the everclean.com website.
I've heard that kittens can be harmed by ingesting cat litter, especially the scoopable kind. What's your position on this?
The Clorox Company is a member of the Sorptive Minerals Institute (SMI), a national trade association that represents the producers and marketers of absorbent clay products, specifically cat litter. The member companies represent approximately 95% of clay cat litter products sold in the United States. When SMI began hearing "rumors" about clumping litter, they interviewed veterinarians, pet store owners and cat owners, asking if they were aware of any health related problems that could be directly attributed to the use of clumping litter. SMI contracted with the National Animal Poison Control Center at the University of Illinois asking them to provide names and comments of any individuals that called regarding health problems that they associated with clumping litter. Whenever possible, these pet owners and their veterinarians were contacted. Autopsies were performed on animals purported to have died as a result of using clumping litter. In every case the autopsy revealed there was some other underlying cause of death, totally unrelated to clumping litter.
SMI even spoke to the holistic veterinary practitioner who first raised this litter issue and she was not able to provide a single piece of evidence linking clumping litter with sickness or death. Even the ASPCA has no health issue with clumping cat litter and they continue to recommend it.
Despite numerous consultations, interviews and tests, neither Clorox, SMI nor any of the veterinarians with whom we have spoken, have been able to find any scientific evidence linking the use of clumping litter with the sickness or death of any kitten or cat.