Caution to use of Corn Based Cat Litters


Corn and moisture are not a good combination; deadly aflatoxin mold can be the result.  While many pet owners avoid corn ingredients in their pet foods because of the concern of aflatoxin, do we now have a new concern with corn cat litters?  One pet owner says a definite yes; the death of her pet raises suspicion to aflatoxin poisoning from Worlds Best Cat Litter; a corn based cat litter.

In late 2005, many pet owners learned a new word to be worried about; aflatoxin.  Diamond Pet Foods contaminated with the deadly mold aflatoxin was recalled; at least 100 dogs were killed.  In October 2009, Wysong Pet Foods recalled numerous brands of pet food due to aflatoxin contamination.  Because of these recalls and the true concern of aflatoxins, many pet owners avoid at all costs corn ingredient in pet foods and pet treats.

But what about corn cat litters?

I hate to admit this, but it’s something I never thought about prior to receiving an alarming email from a pet owner.  “Is it possible that a corn-based cat litter could contain aflatoxins once it has come into contact with a moisture-rich environment (i.e. litter box). My 3 cats began vomiting and one developed hepatic lipidosis resulting in the insertion of a food tube but then developed hind leg paralysis; another developed kidney disease; and the third is now ok once the litter was replaced with clay. Unfortunately, the one with hepatic lipidosis was euthanized because her prognosis was so poor (miss her terribly).”

My first thoughts…of course it could be possible.  With further information, it seems clear it is VERY possible.

From Cornell University Department of Animal Science “the commodities with the highest risk of aflatoxin contamination are corn, peanuts and cottonseed.  Pre-harvest aflatoxin contamination of peanuts and corn is favored by high temperatures, prolonged drought conditions, and high insect activity; while post-harvest production of aflatoxins on corn and peanuts is favored by warm temperatures and high humidity.”

With corn ingredient pet food and cat litter, pet owners first need to trust that the corn was accurately tested prior to pet food or cat litter manufacturing.  Testing accuracy is difficult.  Consider a ton of grain.  Only one small sample of each ton is tested for toxins.  While that one small sample might test clean, it is possible another section within the ton of corn IS infected.  Again, testing accuracy is difficult.

Next, a pet owner has the concern if the corn ingredient pet food and/or corn cat litter was subject to warm temperature and high humidity after production of the product.  This would include warehousing conditions of the product long after it left the manufacturer.  With corn cat litter, this could happen right in your litter box.  Covered litter boxes with added warm urine.

The livestock industry tells farmers that “uninfected corn at 18% moisture can only be safely stored for just over a month at 70 degrees F”.  Broken kernels of corn are three to four times more susceptible to mold growth than intact kernels.

Even clumping corn cat litter and the absolute cleanest litter box – remnants of moisture remain in the box.  Are they growing deadly mycotoxins that could be inhaled and consumed by cats visiting the litter box?  If so, what is the risk to cats?

“Mycotoxins can show carcinogenic, mutagenic, toxic, teratogenic or immunotoxic effects. Mycotoxin exposure in the workplace may occur through inhalation and skin contact, e.g. during occupational handling of organic matter such as livestock feed, food products, or waste. Various studies suggest that both acute and chronic effects can occur, depending at least on the exposure level. The magnitude of the potential health risks associated with a respiratory or dermal intake of mycotoxins has largely remained unclear to date.”  Published 2/26/2009

zeldaThis is Zelda.

Zelda had to be euthanized because of liver failure and numerous other complications.  Zelda’s Mom – JH – is needless to say heartbroken.  JH wanted other pet owners to be alerted to the possibility of risk with corn cat litters.  Below are some of her comments.

“The illnesses of my cats have occurred within such a short period of time (within 4 weeks of switching to Worlds Best Cat Litter in late December 2009).  Soon after euthanizing my Zelda and seeing the decline of my two remaining cats, my husband and I were really puzzled and convinced that they had come into contact with something toxic  The only change that had been made was the litter; so we quickly switched back to the clay, and neither has vomited since.”

“After relaying my concerns about the litter to her primary vet, she said that the presence of aflatoxin would be her main concern, but could not definitively say that was the cause.  I’m still waiting for comments from the specialists who included an internist, oncologist, and cardiologist.  I think that the simple fact there is suspicion and probable cause is enough to warn others.”

Dr. Berryessa from Georgia Veterinary Specialsts (who treated Zelda) stated that “aflatoxin is definitely associated with corn but could not conclusively say that this caused Zelda’s liver failure;  she was cremated and an autopsy was not performed.  He further stated that if this litter is ingested, it could aggravate a cat who has kidney disease because it could contribute to dehydration.”  

The cat litter company, Worlds Best Cat Litter, told JH the lot number was tested clean of aflatoxins.  JH told the company her “concern was not with the product in the bag, but rather what happened to it once it is used as litter and comes into contact with moisture.”

While Worlds Best Cat Litter did respond to JH’s concerns with the litter, an email from their ‘Research Department’ is very suspicious (and down right stupid in my book).  Please take a close look at the sections I bolded…

“We use corn and other ingredients, which meet the standards for pet foods. There are no possibilities of contamination and toxicity issue when the product is in the bag and fresh out the bag. We use a high temperature and pressure process to produce the product and make the product meeting feed/pet foods standards in terms of microorganisms. The product was made in winter (Nov. 29th, 2009) and won’t have any mold or fungi issues in normal conditions unless it has been subjected to high temperature and high humidity or moisture in the litter box.”

‘There are no possibilities of contamination and toxicity issue when the product is in the bag and fresh out the bag.  The product won’t have any mold or fungi issues unless it has been subjected to moisture in the litter box.’

Does Worlds Best Cat Litter understand what cat litter is used for?

I have to wonder if Worlds Best Cat Litter ever bothered to test their products for toxins when it was used as a litter.  I wonder if anyone ever gave the slightest thought to moisture in the litter box.  If anyone ever gave the slightest thought of the pets that would be using this litter.

Dr. Cathy will be adding her concerns in a follow up article soon.

My sincere thanks to JH for allowing me to share her heartbreaking story with readers; her wish as is mine is that by sharing this heartbreak, other lives can be saved.  I hope your other babies fully recover; I hope your broken heart will heal soon.  Zelda will not be forgotten.

Add corn cat litter to your list of cautions for your pets, any corn litter.

In : Pets


  1. Peter

    I use this litter and am concerned. I switched because my cat has seasonal allergy flareups and I wondered if litter could be one of his triggers. It wasnt’ (I switched to SweetScoop, a wheat-based litter), but I stuck with the “natural” litter because I wanted to pursue a cleaner lifestyle for him. SweetScoop is a good product, but does not clump well. World’s best varies a great deal: sometimes it clumps very well… other times, very poorly. I reject the manufacturer’s claims of absolute quality control because the effectiveness of the product varies from bag to bag. So what to do? I don’t want to switch back to “chemical laden” litter… the best defense, it seems to me, is to clean the box immediately or at least, ASAP, at the very least, twice a day. Too many people think cleaning the unfortunate animal’s box once a week is sufficient.

    • Peter

      Aflatoxins are poisons secreted by molds to defend themselves against predators. Those predators would be insects (“storage mites”) but not the cat himself. I can understand the issue of mold formation, given the wet and warm environment of the litter box. But I don’t see a lot of opportunity for infestation by mites… they didn’t come with the product…

      So you’d think that the molds that might form in the litter box wouldn’t necessarily trigger that defense and the risk to the cat would be minimal (assuming he doesn’t eat the litter). So you’d then think… that the litter would be “safe,” and surely “safer” than so many commercial litters which are developed with chemical additives.

      I HAVE, however, experienced infestation of (“grain” or “pantry”) moths… they come into the house with food (often fruit) we think of as “fresh” from the grocery store. A more common source is birdfood, which is often infested in the bag, when you buy it (regardless of cost, not necessarily only in “cheap” bird food). Cheap dry pet foods can come infested. But they can get infested once you open the vaccum sealed bags and keep them in your hoime, or, transfer them to new storage containers. The moths breed in the tiny-est of cracks between cabinets, etc., but they DO seek food sources in the house: oatmeal, rice, and then, you find them in the litter box. The corn must be an attractive food source, whereas clay would not be.

      I clean the litter box so often… as much as a means to extend the life of the litter as concern for the cats. I also wash out the boxes twice or at the very least, once a week, even if I am not “changing” over the litter that day. Most plastic litter boxes are porous, and do need disinfecting more than we think.

      • TJF

        Good point, Peter, on the whole ‘disinfecting’ thing. I didn’t think about that, given I use double black garbage bags as liners, but occasionally a claw will put a hole thru the bag and although it doesn’t APPEAR any urine or anything has hit the plastic box, I think I need to disinfect them and wash them out more anyway. Yeesh. Its always something. And its getting harder and harder to trust what we are feeding, using in the litter box, etc. etc. But I guess, if you think about it, we as humans are becoming more and more distrusting of what WE are eating too ( i.e. GMOs)

  2. Nicole

    You should list the walnut cat litters as a caution as well. We just started using the Blue Buffalo walnut scoopable cat litter and it gets moldy. We took the lid of off the litter box, clean it every day, sometimes more often, and it still gets moldy. I have been experiencing allergic reactions with my sinuses because of this. I switched from Tidy Cat, because it’s chemicals gave me sinus issues, and not this stuff has mold, which I am allergic to. Great.

  3. Lisa

    I’ve been using Tidy Cats Pure Nature for years but recently noticed that some pee clumps develop a sort of white fuzz and I’m concerned that it is a type of fungus or mold. Does anyone have any info on this? The product is made of a combo of cedar, corn, and pine.


  4. Nancy

    I have used Fresh Step Cat Litter and also Arm & Hammer Cat Litter, and when I go to clean the litter boxes out, my face would burn and I would feel a lot of pain in my head and ear, and my lips would burn, my tongue too. Then to top it all off… My stomach and my throat would burn along with my eyes, and everything else. I had to find a litter that DID NOT CONTAIN ANY SODIUM BENTONITE (Carbon), AND ZEOLITES.

    These 2 chemicals are dangerous and deadly to both animals and humans. No matter how many times per day I cleaned the litter box and also washed my face and body, I still felt like I was on fire. That is how badly it had hurt me and my 4 cats. My cats eyes would water up so much that I had to keep tissues around to wipe their little eyes and to have cold water around to dip the tissue in to wipe out the burn. My cats also got very dehydrated from using those cat litters.

    The Fresh Step Cat Litter and that I used was Multi Cat with carbon and it was to kill out the smell of feces and urine. It was the clumping clay.
    The Arm & Hammer Cat Litter that I used was the Natural Essentials Corn Litter.

    Both had also made it hard for me to breathe as well and caused a lot of dust to settle on my entire apt furnishings. They read 99.9% Dust Free! Not even close. There was so much dust on everything in my apt. that I had to wash down and dust every single day!

    Now I am down to trying out a kitty litter called Yesterday’s News which is made of Recycled Newspaper. It reads that it is 99.7% Dust Free. It is pellet form, and flushable. I don’t like it! It is very hard, and there is no possible way to scoop it out of the litter box at all with a scooper. My cats don’t even like using their litter box any more with that litter in their box. They prefer to use my bathroom floor because of the new litter! This is way too much for me to stand any longer.

    There has got to be a litter out there without any Sodium Bentonite and Zeolites in it or Fragrances! I will have to keep searching for a decent litter that is not going to harm me or my kitties ever again. If there isn’t any such litter around… I am going to straight sand or sterilized potting soil!

    Those other litters that I had mentioned above also made my cats vomit! So please try to find a litter that isn’t going to make you and your loving kitties sick and kill you, and them in the process.

  5. Bonnie

    I just changed to World’s Best from Arm & Hammer due to the scent. If I can’t stand the scent how can my multi cat household. Does anyone have a suggestion on what to use when u have more 5 litter boxes in a home?

  6. TJF

    I have two 15 pound cats and I have used the Worlds Best for the past couple years, scoop twice a day and toss all about every 10-14 days. But now I am concerned.

    I live in South Florida in the sub tropics as it is, a hotbed of mold, etc. just in our everyday environment. We have the AC on deep freeze but that doesn’t seem to stop mold and tropical creepin’ crud.

    WB It is the only one of the clumping litters that I am not horribly allergic to, but just in case, I wear a face mask while cleaning the box. I am that allergice, but I don’t have any issues with this litter relating to that.

    I used to use the non clumping clay generic from my local grocer….and now I am thinking of just going back to that.

    I used to get 20# for about 5 bucks and tossed the whole thing ever three days.

    I always use a garbage bag liner and large cat boxes so I just grab the ends and pull the whole thing off the box, and toss.

    This is very concerning. I liked Worlds Best, the best of all, but I agree with the poster who said that some bags clump better than others.

    Just in the couple months, the last couple bags have not had the clumping ability it has normally, which I figured was a quality control issue. Still, it is the best I have found. But now I am worried, not only because of corn and moisture, but also because of where I live, which would add to the problelm.

  7. Lisa

    I started using Feline Pine Clumping. It works well and there’s no worry about aflatoxin because it’s all pine and no corn.

  8. cynthia

    I wonder if one thing that may make the corn-based, flushable litter particularly susceptible to mold, fungus, and aflatoxin poisoning is that the litter box is usually kept in the bathroom where the waste can be flushed, since that aspect is one of this litter’s most attractive features. I would imagine that the heat and steam of people showering daily create exactly the hot and humid conditions that encourage spoilage and toxicity problems. We have long been pushing the litter box out into the hallway whenever someone takes a shower, just so that the litter didn’t get moist and would stay fresh longer. Now it seems there is even more critical reason to do so. I am so sorry to learn there are safety issues with this litter, since we carefully selected it after reading about all the health risks (as well as environmental pitfalls) of using the clay-based and chemical-based litters, and I have to say the newspaper-based litter worries me as well. Questions about the chemical toxicity of the ink is the first question that comes to my mind. Indeed it is ALWAYS something. I guess for now we will stick with World’s Best but be ever more careful about moisture around it.

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