problems with silica gel cat litter

Problems with Silica Gel Cat Litter

How safe are your cats with silica gel cat litter?

Silica gel  cat litter is often touted as harmless to humans and animals alike. However,  some people use crushed silica gel to kill bed bugs and cockroaches!

The following excerpts from THREE different sources might serve to illustrate exactly how harmless it really is as cat litter.

We have begun with the least alarming of the three instances; please click here to skip to the part that could save someone’s life – maybe yours.

We have been using “crystal” cat litter that is a silica gel for several months. It is far and away the best litter we’ve tried in terms of odor control and ease of use.

However there is a tremendous amount of dust emanating from the stuff. It is so heavy, I fill the box by taking it outside, holding the bag several feet above the box, and pouring slowly so the dust blows off in the breeze. I hold my breath too. If by chance I breathe it, intense coughing is the result.

I’ve also noticed a few times, that when the box is fresh, the cat will leave the box and wheeze a few times


And this one is from a case study on silica  in cat litter and its effect on cats :

Inhaled silica dust has been implicated as a cause of lung cancer and other respiratory diseases in humans and several animal species.

Electron microscopy and x-ray spectroscopy were used to identify and characterize dust particles from seven brands of commercially available clay cat litters and to identify, characterize and quantify particles in the lung wash fluid of six cats with and six cats without signs of respiratory disease.

Dust particles from clay cat litter have an identifiable appearance and elemental ratio (primarily aluminum and silica) and the same pattern was observed in particles obtained from lung wash fluid. Significantly more silica particles were obtained from cats with than without respiratory disease.

This suggests an association between presence of silica particles and respiratory disease, but it is unknown whether silica dust particles contribute to respiratory disease or accumulate because of interference with normal lung ciliary function.


What exactly is Silica Gel Crystal Cat Litter?

Silica crystals are filled with millions of micro pores that adsorb moisture.  Silicon dioxide (the type of sand found in quartz), when mixed with oxygen and water, turns into Silica Gel Crystals. The crystals are super adsorbent and suck the moisture out of kitty poo. No wonder it is so popular amongst cat owners.

What we see as silica cat litter is frequently a synthetic form of silicon dioxide derived from sodium silicate. It is a fairly recent innovation and was patented by Professor Walter A. Patrick in 1918.

Adsorb vs Absorb

A substance is adsorbent when other substances (dissolved solid/liquid/gas) stick to its surface (or adhere to it) at a molecular level.

Other than silica gel, activated charcoal is a good example.

Even though silica gel is extremely porous at microscopic level, the liquid (which includes dissolved solids) part of cat excrement just forms a film on the surface of the pores instead of being sucked inside of them (and sort of becoming a part of them).

A substance is absorbent when other substances (liquids) are dissolved in it or can permeate it.

Example of dissolve: ink being dissolved in water.

Example of permeate: ink being soaked up by blotting paper.

Clumping cat litter (with or without sodium bentonite) will absorb the fluid from cat excrement and form a solid clump of varying degrees of hardness.

(Source and Further Reading)

Sodium Bentonite is not the only cat-litter culprit.  Clay is harmful if inhaled in dust form. Apart from that, in clay based clump cat litter,  silicon constitutes most of the dust particles. That is not a healthy situation for either the human members of the household or the one with the paws using the litter. Silica Gel Cat Litter

The possible carcinogenic (causing cancer) property of silica, and the disease Silicosis  should not be taken lightly, either (although silicosis is suspected to occur from dust that comes of natural silica).

The blue colour often found in silica gel cat litters that indicates that the litter is fresh (it turns pink upon absorption of moisture) is due to the presence of Cobalt Chloride. This, again, is ‘possibly carcinogenic’ to humans and definitely hazardous to aquatic life and to the environment in general (use of Cobalt Chloride has been restricted in Europe since 2000 after being reclassified as a carcinogen).

Cobalt Chloride free Silica Gel is being made available in the market for precisely that reason though not as cat litter.

Is silica gel cat litter safe for humans?

Please bear with us while we explain the connection between Sarcoidosis and silica gel cat litter – you’ll likely find this as shocking as we did.

What on earth is Sarcoidosis?

Silica gel cat litter is a possible trigger for Sarcoidosis
Image courtesy:
Click to open large image.

Sarcoidosis (SAR-KOI-DOSIS) is a disease caused when the body’s immune system overreacts. While it is not yet known exactly what causes the overreaction there is reason to believe that it may be triggered by a response to some specific substance inhaled from the air (like dust from silica cat litter, perhaps?).

The most visible symptom is the formation of granulomas which appear as unnatural lumps or nodules. These are caused by inflamed cells clumping together. Most frequently affected organs are the lungs and the lymph nodes but other organs may be affected as well.

Good news is, Sarcoidosis has been known to go away on its own and with supportive medication patients can live a close to normal life.

Bad news is, there is no known cure for Sarcoidosis. If it takes an aggressive turn, the granulomas can cause irreversible damage to the affected organs.

There are about 200,000 individuals affected by Sarcoidosis in the US.

Among the most prevalent symptoms are:

  • Unexplained shortness of breath
  • Swelling and pain at joints and extremeties
  • Unnatural or missed heart beats (arrhythmias)
  • Hearing loss
  • Seizures
  • Blurry vision and symptoms like conjunctivitis
  • Tender bumps and patches on the skin
  • Psychiatric disorders like dementia and psychosis or even general depression

Sources: WebMD, Mayo Clinic

Here is a video to round off this part of the discussion. We suggest you skip it for now and scroll down to read what is arguably more important for you if you’ve been using silica gel cat litter.

(Silica Gel) ‘Cat litter is a possible trigger for sarcoidosis’

Excerpts from study published in the European Respiratory Journal, December 31, 2011


Inorganic agents, including silica, have been reported to initiate inflammation and granulomatous reactions… We propose that silica, the major component of cat litter, might be such an agent.

We report a case of biopsy-proven sarcoidosis with birefringent material, mainly silica, within the lung biopsy specimen. The patient had no relevant occupational history, but had cats and was extensively exposed to silica-containing cat litter.

Initially, the patient improved after starting immunosuppressive drugs and terminating contact with litter. However, she deteriorated twice after autoprovocation (re-exposure) to cat litter. After changing the silica-containing cat litter for litter without silica, her clinical condition improved substantially.

Obviously, she appeared to be “hypersensitive” not to the cats but to the cat litter.


Although crystalline silica exposure has been known to be associated with sarcoidosis, the present case provides evidence of an unexpected association between the substantial exposure to silica-containing cat litter and sarcoidosis or a “sarcoid-like” granulomatous reaction.

Obviously, this is important, as many people have cats with litter boxes.

Therefore, it was recommended not to get rid of the cats but rather choose appropriate cat litter, without silica.

This case stresses: “if you are not aware of it, you will not recognise it!”

You should probably read the entire article.

If that doesn’t convince you to reconsider your decision to use silica gel cat litter, we don’t know what will.

There is a growing resentment among patients of Sarcoidosis that since the number of people affected is relatively low, there hasn’t been much research on determining a cure.

The theory (which makes sense, actually) is that Big Pharma funds most such research works and it wouldn’t make sense to fund a research that might serve to bring relief to a small number of people. The investment simply wouldn’t be worth it.

Be that as it may, one cannot help but wonder what might turn up if more studies along the lines of the one we cited are conducted.

Is any silica gel cat litter safe?

We’re not sure, but in all fairness, we should mention the Ultra Pet brand which claims to use a vegetable dye instead of cobalt chloride and says the following about dust:

There may be a small amount of powder on the product, but generally the product is over 99% dust free. This is the result of pearls rubbing together during transport. Once you have opened the bag you shouldn’t have any problems with dust—if you do please call us.

The brand also claims to be relatively environment friendly:

…70 percent less landfill contribution than clay litter.

However, we would still recommend organic alternatives because they get the job done while being 100 percent eco-friendly.

If you wish to know about organic alternatives to silica gel litter, please read our post on Organic Cat Litter.

And if you are convinced by now that there is more to Silica Gel Cat Litter than meets the eye, please click on the sharing buttons below to spread the word.

11 thoughts on “Problems with Silica Gel Cat Litter

  1. Comment moved manually from old site

    Skyler ([email protected]) says on 2016/07/05 at 11:34 pm:

    I don’t know if I like it or not. It scares me a little to be honest. I just got my kitten and everytime she goes in she ends up eating them. I end up taking it out of his mouth. Is it ok? Is it bad for my cat? What should I do about my cat eating it?

  2. Comment manually moved from old site:

    Stephanie Moon ([email protected]) says on 2016/04/27 at 12:05 am

    Brilliant discovery!
    Use horse or chicken pellets, they are super cheap 15$ 20kilo bag , bio degradeable and the cats love using them. I am a recent convert from the silica.

  3. Comment manually moved from old site:

    Beth ([email protected]) says on 2016/01/15 at 11:56 pm:

    I am currently using Ultra Pet silica litter (the very fine one, the one that looks like sand). I have been using it for several months. While my cats LOVE it, even with daily vacuuming of the floors, every surface in the room with the litter box, including books, desk, computer, etc. is covered with a layer of silica dust. I can SMELL silica dust in the room when I am in there. I have no choice but to look for some alternative litter at this point as it is truly disgusting and I go into that room as little as possible except to stir the litter per directions and clean the box per directions. I am very unhappy (although my cats are happy) with this litter and do not recommend it.

  4. Thanks for adding to the discussion, everyone… will be coming up with something new shortly, would welcome your comments again.

  5. This is research by a journal.

    “Occupational exposure associated with respiratory diseases
    Silicosis (chronic, accelerated, acute)
    Progressive pulmonary fibrosis
    Chronic obstructive pulmonary diseases
    Lung cancer
    Increased risk for TB
    Occupational exposure associated with other diseases
    Systemic autoimmune diseases
    Rheumatoid arthritis, SLE, scleroderma, small vessel vasculitides
    Renal Disease
    Glomerulonephritis, nephrotic syndrome, end-stage renal disease

    • Comment manually moved from old site:
      In reply to Monica, El Bee ([email protected]) says:

      Monica, the silica (“silica GEL”) in cat litter is NOT, contrary to the name of the products, crystalline silica; it would not pass federal regulations to sell in the USA, anyway! Silica gel is the harmless stuff that keeps shoes from getting moldy when stored or shipped. It’s in almost all grains, both “whole” and processed, and most processed foods contain it. What you’re talking about isn’t remotely similar and can’t even FORM this shape–the MOLECULES are “crystalline” in appearance, but it’s NOT the same silica. If silica gel were fatal, so would going to the beach and eating anything you didn’t farm yourself.

  6. The walmart “mimi” brand crystal cat litter gave my daughters Russian Blue long-hair cat a severe UTI to the point of bleeding. I’m convinced Cheri would have died had I not changed the litter to “Special Kitty” 100% natural clay (non-clumping brand). Within 24-36 hours of changing the litter, she totally stopped bleeding as well as frequent urination and returned to her normal self. Crystal litter may be easier for cat owners, but my experience says it’s possibly fatal to the kitties having to use it.

    • Comment manually moved from old site:
      In reply to Rebecca, Kaibeezy says on 2016/04/08 at 10:48 am

      White silica gel cat litter saved my cat’s life. I noticed one day her urine was very slightly pink. The vet saw her that day and diagnosed a hidden kidney condition that would have killed her quickly, but because we caught it so early, she lived happy and healthy for many more years. I never would have seen the stain in anything but the pure white silica litter. That’s a real and significant benefit that far outweighs any marginal, mythical, pseudo-scientific “danger”.

  7. You are correct that crystalline silica can be cause problems like silicosis, but you are mistaken in thinking that silica gel cat litter is the same, it is not, there is crystalline silica naturally occurring in a lot of clays and therefore it can be in clay litters though. The silica gel is amorphous silica, the silica in clays is crystalline and that causes health problems, aka potter’s rot, quarry lung, medically known as silicosis. Breathing in lots of any dust is not good. But the science just isn’t there to to support that amorphous silica is as bad as crystalline silica. Diatomaceous earth is basically amorphous silica-yes it can kill some insects by dessication same thing it does to poop and pee and those little silica packs in vitamins. Synthetic amorphous silica is in cat litter, rubber, epoxies, agroproducts, in human food, pet food. Too much of anything can kill you. Even pure water can be toxic if you drink too much. Flour can cause lung problems similarish to silicosis, it is called baker’s lung. The issue is degree of exposure. If the dust bothers you then wear a face mask when pouring, that is the time you and your cat will be most exposed. It is unfortunate that so many manufacturers call it crystals, because technically that is wrong. It is not crystalline, the crystal is not absorbent, otherwise your glass windows wouldn’t keep out the rain or the beach would soak up the ocean! Perhaps the bigger health concern is it pure? Amorphous silica can be contaminated by crystalline silica and that would be a hazard.

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