The question does not specify whether it refers to cats or people. I will therefore deal with both. It’s different for cats because they are much closer to the cat litter and they rummage around in it. Also, I’m going to presume that the question refers to clay-based cat litter which contains a clumping agent called sodium bentonite. It’s used in most major brands of clumping clay cat litter. It is very popular and used widely. Anecdotally there are reports (or a single report) of cats brought to veterinarians having ingested litter containing sodium bentonite. As this litter expands tremendously when it gets wet it can cause serious illness if it is ingested.
However, to the best of my knowledge, there have been no studies, or I couldn’t find one, on the dangers of standard clay-based litters to both human and cat. I don’t think that *in general* there is a problem with ingesting this type of litter although I would be more concerned about cats than people. I am not saying that it is 100% safe. There are issues but I don’t believe they are so grave as to worry people. However, lightweight litters can be different…
Tidy Cats Lightweight Litter
There is one cat litter brand, Tidy Cats Lightweight Litter, which is reportedly dangerous to cats and is probably more hazardous to people as well because it creates more dust. I wrote about this some time ago on a Blogger site which acquired over 100 comments useful from people who have had bad experiences with it (click this to read it). Once again there is no scientific study but I would read the page if you are concerned. If you agree with the comments find an alternative.
In respect of this litter I also have a page written by a person who worked in a factory producing it and his observations are also enlightening (click to read it). The litter contains crystalline silica which is abrasive and another article alleges that it killed four Tonkinese kittens.
Tidy Cats Lightweight Litter is made with perlite which is extremely abrasive…
Note: things change and the manufacturer may have dealt with these concerns. I am flagging up an potential problem.
If you’re concerned about your cat using clumping litter containing sodium bentonite, there are alternatives which are more environmentally friendly. Remember that litter clay is stripped mined which cause environmental damage and it has to be thrown away which also causes environmental damage. More natural substances or recycled substances are probably better. I’m not promoting any particular litter but there is one in America made from recycled newspaper which is reportedly three times more absorbent than clay. It is non-toxic and contains no scented fragrances (which can also be hazardous). It is 99% percent dust-free and it’s called Yesterday’s News. Wood shavings and sawdust make good cat litter substrates as well. NEPCO’s Cedarific Natural Cat Litter is a mixture of hardwood and seeded chips with no clay or silica dust. It is a 100% all natural cat litter made from natural wood fibres and dust free and soft to the touch they claim.
There is also a litter made from wheat called SwheatScoop Natural Wheat. It contains natural enzymes which reduce odours. It is low dust and low tracking and both the wood-based litters and this one are biodegradable and compostable – also advantages aspects. You can throw into the mix World’s Best Cat Litter made from whole kernel corn and Benevo Cat Litter made from non-genetically modified maize and other vegetable derivatives.
These are good alternatives which are more environmentally friendly and there are no dust issues which is the problem that people are concerned about.
Lightweight cat litters, characterised by the one that I have mentioned, are probably the most hazardous because lightweight equates to the dust being more able to float up to a person’s mouth were it can be inhaled. And clearly cats being much closer to it are far more likely to ingest it.