We like World's Best Cat Litter for three reasons:
First, it's not clay. Clumping clay litter often contains sodium bentonite - which itself is a form of clay, and there are concerns that it
can be a contributing factor in gastrointestinal blockage in cats. Kittens are particularly vulnerable to sodium bentonite toxicosis, and many shelters (including ours) instruct foster families to avoid clay litters for that reason.
Second, it's not clay! Clay litter also contains silica dust, which can cause respiratory problems if inhaled.
Third, it's biodegradable and made of 100% natural, plant based materials. This also means it's eco-friendly, since clay litter use promotes clay strip mining.

Recently we were asked to review their newest litter formulation, the Advanced Natural Series. World's Best very kindly sent us a free bag to test out, and here are our findings:
According to the press release, this is a new advanced formula specially made for "high performance clumping."
We were happy to hear that this new formula still retained its all-natural, plant based ingredients.
But I was worried that this new version was not going to be flushable, and I immediately noticed there was no mention of that in the press release for this new formula.
So I wrote and asked about it.
Here's what they said: "Consumers have been flushing our product for years and we are not aware of any issues that it has caused. But due to changing laws, we are in the process of getting the needed testing to make this claim on bags or our website in the future."
I'm happy to hear they're actively pursuing the testing so they can actually promote this on their bags. Personally, I think this would be a huge win for them - it's certainly the reason I use their brand.
My understanding is that currently, your city or township's sewage treatment plants may have local policies that allow for flushing plant-based materials and you should check with them before flushing. Or if you live out in the country and have a septic tank, you'll need to follow the guidelines laid out by the septic manufacturer on what's flushable and what isn't.
So is it really better at clumping?
I hate dust in the litter area, which is one of the many reasons I refuse to use clay-based litter products. So I wondered how this new bag would stack up against their existing, almost dust-free Multiple Cat formula. I was happy to
see that the litter looked as coarse as Multiple Cat. So far, so good!
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Advanced Natural formula on left, Multiple Cat on right |
I filled two of our 4 litter boxes from our standard Multiple Cat bag, then used the other two to test the new Advanced Formula bag. After a week of testing? Their press release wasn't kidding. It does seem to clump slightly better. And it does as good a job at odor control as the Multiple Cat. I'm very happy with this product.
Giveaway Time!
Anyone want to test drive a free bag? World's Best is offering one free bag of their Advanced Natural Series to our readers - U.S. only. (please see rules & disclaimer below)
All you need to do is tell us you're interested in entering the giveaway, and indicate which scent you prefer, if your name is chosen. You can select either Original Scent - which we found to have a pleasantly mild, slightly nutty smell - or the Pine Blend.
Good luck! A winner will be chosen by Random.org and announced next Friday, August 2.
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Rules and Disclaimer:
No purchase necessary to enter. Void where prohibited or restricted by law. Winners are chosen using random.org and will be notified by e-mail. The winner of the giveaway will need to give us a physical address (no P.O. boxes please) to which the prize will be mailed within 72 hours.
If a reply email containing the physical address where the prize should be mailed is not received, an alternate winner will be chosen again by random. The winner will be announced in a separate post following the drawing.
We were given a bag of litter by World's Best to review, but were not compensated for hosting the giveaway. All opinions in this article are our own.
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EDIT: Thanks to Connie of
Tails from the Foster Kittens who caught a few typos and helped me realize I hadn't included all my source links. It's bentonite
toxicosis, (not toxosis) and it was written up in the journal
Veterinary and Human Toxicology in 1997 (
abstract can be found here).
It's also important to distinguish between sodium bentonite and calclium bentonite.
Sodium Bentonite is used in oil drilling, clumping cat litter and as a bonding agent in cosmetics and medicines, and even some livestock feeds. It's currently being investigated as a way food producers can ensure E. Coli bacteria removal prior to delivering produce to market. It's also used in the filtration of protein sediment in beer and wine.
The danger of toxicity appears to be in free quartz particles, which can present an inhalation hazard. And according to californiaminerals.com, this particular type of bentonite often has an exaggerated caustic Ph value.
The danger of intestinal blockage is also much higher in sodium bentonite than in other forms of the clay. Depending on the amount of montmorillonite (a mineral) found in its composition, sodium bentonite has the ability to expand to up to 20 times its volume in the presence of water.
Thanks to Connie, we have a story that links clumping cat litter (containing
sodium bentonite, not
calcium bentonite) to
the death of a basset hound who ingested it.
Calcium Bentonite, on the other hand, has been used medicinally for centuries by humans all over the world to detoxify. A simple google search will reveal a ton of products on the market for both internal and external cleansing and purifying of the body - everything from a colon cleanse to an herbal whole body supplement to detoxifying soaps and baths.
The important thing to know about Calcium Bentonite is how it differs from Sodium Bentonite. Many of the products you find when googling assure you that their calcium bentonite product is a way for you to "alkalize
safely" (a reference to the caustic Ph value of sodium bentonite).
And research in 2007 by Arizona State University even indicated that calcium bentonite clay might have antibacterial properties!
Sadly, it's not calcium bentonite that is in our litters.
One last thing to note: the FDA does not distinguish between Sodium and Calcium Bentonite, and classifies it as GRAS (Generally Recognized as Safe)
only under the following conditions:
"to
assist in the clarification of juices, beverages, and other food
products, as a binding agent for the preparation of pelleted animal
feeds, and as an ingredient of coatings and adhesives for food packaging
materials."
(source:
http://www.accessdata.fda.gov/scripts/fcn/fcnDetailNavigation.cfm?rpt=scogslisting&id=35)
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Sources on sodium bentonite:
http://www.livestrong.com/article/184332-what-are-the-types-of-bentonite-clay/
http://www.engr.colostate.edu/ce/homepages/shackel/Papers/35.pdf
http://www.clays.org/journal/archive/volume%2010/10-1-272.pdf
http://www.californiaearthminerals.com/science/clay-minerals-research.php?16
and
http://digitalfire.com/4sight/hazards/ceramic_hazard_bentonite_toxicity_31.html
Sources on calcium bentonite:
http://www.clays.org/journal/archive/volume%2010/10-1-272.pdf
http://researchmatters.asu.edu/stories/healing-clay-906
https://www.google.com/search?q=calcium+bentonite+purification&oq=calcium+bentonite+purification&aqs=chrome.0.69i57.9324j0&sourceid=chrome&ie=UTF-8#q=calcium+bentonite+detox&source=lnms&tbm=shop&sa=X&ei=TLHyUeHQLNLKqQGX-YFI&sqi=2&ved=0CAkQ_AUoAw&bav=on.2,or.r_cp.r_qf.&fp=85154c461bfcc325&biw=1551&bih=918&bvm=pv.xjs.s.en_US.MpiVkF51mpA.O