Formaldehyde in Cat Litter: Where It Comes From, and How to Read a Test Report

Written by the Kopipets team · Singapore · Published 31 July 2026 · Last checked against published standards and test data 31 July 2026
We sell tofu cat litter, so read this with that in mind. We have tried to write the version of this page we wanted when we first started asking our own suppliers about it. It contains one link to our own test results and no product links.

The short version

Formaldehyde in cat litter does not come from the tofu. It comes from whatever is holding the pellet together.

Soybean or pea residue on its own does not clump and does not hold a shape. Something has to bind it. There are two families of binder in common use. One is food-grade — starch, guar gum, sodium carboxymethyl cellulose. The other is the adhesive family used in particleboard and plywood, built on urea-formaldehyde or phenol-formaldehyde resin. The second family is cheaper, binds harder, and releases formaldehyde slowly over the life of the product, faster in heat and humidity.

That is the whole mechanism. Everything else on this page is about how you find out which one you have bought.

Why this is a Singapore question and not a general one

Urea-formaldehyde resin does not lock formaldehyde away permanently. The bond hydrolyses — it comes apart in the presence of water — and the rate goes up with temperature and humidity. This is well known in the furniture and flooring industries, which is why board emission grades are tested under controlled temperature and humidity rather than at room conditions.

A flat in Singapore sits at around 30°C and 80% relative humidity for most of the year. A bag of litter that spent six weeks in a container and then three months in a storeroom here has had a different life from the same bag sitting in a dry northern warehouse. We are not able to give you a number for how much difference that makes, and we are suspicious of anyone who offers you one. But the direction is not in dispute, and it is the reason we think the binder question deserves more attention here than it gets elsewhere.

We made the same argument, less precisely, in our earlier piece on whether tofu cat litter is safe. This page is the layer underneath it.

There is a published limit. It is 1.5 mg/kg.

The most specific published standard for this product type is T/CIQA 11-2020, the tofu cat litter specification issued by the China Inspection and Quarantine Association. It sets a maximum formaldehyde content of 1.5 mg/kg in the litter itself.

Two things about that number that sellers rarely tell you.

First, it is not the only standard. When four consumer councils — Macau, Shenzhen, Zhongshan and Guang'an — ran a comparative test on 40 cat litter products in 2025, they benchmarked against four different documents depending on the litter type: GB/T 43839-2024, T/SDPIA 05-2022, T/CIQA 11-2020 and T/ZGXX 0005-2022. So when a listing says "tested and compliant" without naming a standard, it has told you nothing. Compliant with which one, and at what limit?

Second, 1.5 mg/kg is a content limit, not an exposure limit. It describes how much formaldehyde is in a kilogram of the material. It does not describe how much ends up in the air of your flat, which depends on release rate, tray size, room volume, ventilation and time. The WHO indoor air guideline people usually quote — 0.1 mg/m³ over 30 minutes, from the 2010 Guidelines for Indoor Air Quality: Selected Pollutants — is an air concentration and is measured in a completely different way. You cannot convert one into the other on the back of an envelope, and we are not going to pretend to.

What the content limit is good for is comparison. It lets you put two products side by side against the same ruler. That is worth a lot, and it is all it is worth.

How to read a cat litter test report

Most "test report" images circulating in product listings are photographs of a single page, often the cover. Here are the five questions that decide whether a report means anything.

1. Which standard, and what is the limit?

A result of "0.8 mg/kg" is meaningless on its own. Against a 1.5 mg/kg limit it passes comfortably. Against a hypothetical 0.5 limit it fails. A report that gives you a figure without the standard and the threshold next to it is asking you to do arithmetic you have not been given the inputs for. This is the same problem as a litter advertised as "low dust" with no percentage and no limit — we wrote about that at length in our tofu cat litter buyer's guide.

2. Is there a report number, and can the lab confirm it?

Real laboratory reports carry a report number and usually a verification code that lets you check the document against the lab's own records. If the seller will not give you the number, you are looking at a picture, not a report.

3. What was the detection limit?

This is the one almost everybody skips. "Not detected" means below the level this method could see. It is a statement about the instrument as much as about the sample. A method with a detection limit of 0.1 mg/kg and a method with a detection limit of 1.0 mg/kg can both print "not detected" on identical samples, and they are not saying the same thing. A report that says "not detected" without stating the limit of detection has left out the most important half of the sentence.

4. What date, and which sample?

A report covers the samples that were submitted, on the date they were tested. It is evidence about a production run. It is not a permanent property of the brand name on the bag. A report from 2021 attached to a listing in 2026 is telling you about a batch that no longer exists.

5. How many items were tested, and are all of them shown?

If a seller publishes one favourable line out of a multi-item report, you are being shown a selection, not a result. The honest form is the whole page.

What our own report says, including the parts that constrain it

Our tofu litter was tested by CTI against T/CIQA 11-2020 in April–May 2025, report number A2250276330101001C. Seventeen items were tested. Formaldehyde was not detected, at a detection limit of 0.1 mg/kg, against the standard's limit of 1.5 mg/kg.

All seventeen results — including the ones that are merely adequate rather than impressive — are published in full on our test report page, with the report number and verification code, so you can apply the five questions above to us before you apply them to anyone else.

Three limits on what that report proves, which we would rather state ourselves than have someone else point out:

It covers the samples submitted in 2025. It is strong evidence about how that product is made and weak evidence about a bag manufactured in 2028. We intend to re-test rather than keep pointing at one document, and when we do, the new report goes on the same page next to the old one rather than replacing it.

T/CIQA 11-2020 is a Chinese association standard. It has no legal force in Singapore, and as far as we can establish Singapore has no formaldehyde limit written specifically for cat litter. We use it because it is the most specific published benchmark that exists for this product category, not because it is binding here.

And we are not going to tell you on this page that our binder is starch-based. We believe it is. We have not yet received that in writing from the manufacturer with a specification attached, and until we have, it is a thing we have been told rather than a thing we know. When the written specification arrives it goes on the test report page. If it turns out we were wrong, that will go there too.

"Not detected" and "formaldehyde-free" are not the same sentence

This is the part we would most like people to take away.

"Not detected below 0.1 mg/kg, in these samples, on this date, by this method" is a measurement. It has boundaries, and the boundaries are what make it useful.

"Contains no formaldehyde" is a claim about every pellet in every bag we will ever sell. No test produces that. Formaldehyde also occurs naturally at trace levels in a great many plant materials — it is an ordinary metabolic intermediate — so "zero" is not even a chemically coherent target. It is a marketing sentence wearing a lab coat.

There is a practical reason to care beyond pedantry. Under Singapore's Consumer Protection (Fair Trading) Act, a trader making an absolute claim is expected to be able to support it. A brand that has written "100% formaldehyde-free" across its packaging has taken on a burden of proof it cannot discharge, and the fact that it did so cheerfully tells you something about how it treats its other claims. We would rather publish a number with its limit attached and let you judge it. We have made this mistake ourselves in other places on our own packaging, and are in the middle of fixing it.

What the wider testing actually found

The four-council comparative test published on 26 November 2025 is the most useful independent reference point we know of, because it is not a brand's own commissioned report. Forty products, four categories — mineral, tofu, bentonite and mixed — and nine indicators: arsenic, lead and formaldehyde on the safety side; clump height, clump strength, powder content and pulverisation rate on the physical side; deodorisation rate and water absorption on performance.

On the three safety indicators, all forty samples met the applicable standards. That is worth saying plainly, because it cuts against the way this topic is usually discussed online. The most likely outcome when a mainstream product is tested is that it passes.

Where the products separated was on the physical indicators. Powder content across the forty ranged from 0.05% to 3.48% — a factor of seventy between the cleanest and the dustiest. Pulverisation rate ranged from 0.28% to 1.20%. Those are the numbers that describe what your floor and your cat's paws actually experience, and they varied enormously between products that were all, equally, "safe".

Our reading of that: formaldehyde is the thing worth checking once, at the point where you decide to trust a manufacturer. Dust is the thing you live with every day. Both matter. They do not deserve equal airtime, and the internet currently gives them the reverse of the right proportions.

If you cannot get a report at all

Most litter on sale here does not come with one. Three things you can do that are better than nothing:

Ask for the standard number and the limit, not for reassurance. "Is it safe?" gets you a yes from everybody. "Which standard was it tested against, what is the limit for formaldehyde under that standard, what was the result, and what was the detection limit?" gets you either an answer or a silence, and the silence is also an answer.

Look at what the binder is called on the ingredient list. Starch, guar gum, cassava, corn starch and sodium carboxymethyl cellulose are food-grade binders. A list that declines to name the binder at all is a list that has decided not to tell you.

Treat a sharp chemical smell as a reason to stop, but not the absence of one as clearance. Formaldehyde does have a pungent smell, and a fresh bag that hits you when you open it is a genuine warning. But the concentrations that matter can sit below what a nose reliably registers, and a scented litter can mask it completely. The test works in one direction only.

Where we could be wrong

We are a pet supplies retailer. We are not a toxicologist, a chemist or a laboratory, and nothing here is veterinary advice. If your cat has a respiratory condition, ask your vet before changing litter, not us.

Two things specifically that you should not rely on us for. We cannot tell you what any content figure in mg/kg means for the air in your flat — that is an exposure calculation requiring assumptions we do not have data for. And the evidence base on formaldehyde exposure in cats specifically is thin. Formaldehyde has been classified by IARC as Group 1, carcinogenic to humans, since 2004, and cats spend more time closer to the litter surface than we do and groom what settles on their paws, so the concern is reasonable on its face. But "reasonable on its face" is not the same as quantified, and we are not going to dress the one up as the other in order to sell you something.

If you find an error on this page, or a source that contradicts it, we would rather hear about it than not.

Questions we get asked

Does tofu cat litter contain formaldehyde?
Some does and some does not, and it depends almost entirely on the binder used to hold the pellet together rather than on the soy or pea residue itself. Litters bound with food-grade starch and guar gum have no formaldehyde source in them. Litters bound with urea-formaldehyde or phenol-formaldehyde adhesive do, and release it slowly over the product's life.

What is the formaldehyde limit for tofu cat litter?
T/CIQA 11-2020, the Chinese association standard for tofu cat litter, sets a limit of 1.5 mg/kg of formaldehyde in the litter. It is a content limit rather than an air-exposure limit, and it is not a Singapore regulation — Singapore has no formaldehyde standard written specifically for cat litter that we are aware of.

Does "not detected" mean there is no formaldehyde?
No. "Not detected" means the amount present was below the detection limit of the method used, in the samples tested, on the date tested. A report that says "not detected" without stating the detection limit has omitted the most important part. Our own report reads "not detected at a detection limit of 0.1 mg/kg", against a standard limit of 1.5 mg/kg.

Is Kopipets tofu cat litter formaldehyde-free?
We do not make that claim and we do not think anyone should. What we can say is that CTI tested our litter against T/CIQA 11-2020 in April–May 2025 under report A2250276330101001C and formaldehyde was not detected at a detection limit of 0.1 mg/kg. All seventeen results from that report are published on our test report page.

Can I smell formaldehyde in cat litter?
Sometimes. A sharp chemical smell from a freshly opened bag is a genuine reason to stop using it. But the absence of a smell does not clear a product: the concentrations that matter can fall below reliable odour detection, and scented litters can mask it. Use smell as a warning sign, never as an all-clear.

Is formaldehyde in cat litter dangerous to cats?
IARC has classified formaldehyde as Group 1, carcinogenic to humans, since 2004, and cats sit closer to the litter for longer than people do and ingest what settles on their paws when grooming. The species-specific evidence for cats at litter-level concentrations is thin, so we can tell you the concern is reasonable but not how large it is. If your cat has a respiratory condition, discuss litter choice with your vet.

Has independent testing found formaldehyde problems in cat litter?
In the largest recent comparative test we know of — 40 products across four categories, run jointly by the Macau, Shenzhen, Zhongshan and Guang'an consumer councils and published on 26 November 2025 — all forty samples met the applicable standards on arsenic, lead and formaldehyde. The products differed far more on dust: powder content ranged from 0.05% to 3.48% across the same forty samples.

Sources and standards referred to

T/CIQA 11-2020, Tofu Cat Litter, China Inspection and Quarantine Association — the formaldehyde limit of 1.5 mg/kg and the standard our own product was tested against.
GB/T 43839-2024, T/SDPIA 05-2022 and T/ZGXX 0005-2022 — the three further standards applied alongside T/CIQA 11-2020 in the four-council comparative test, cited here to show that "tested to standard" is not a single thing.
Four-council comparative test of 40 cat litter products, published 26 November 2025.
Agents Classified by the IARC Monographs — formaldehyde, CAS 50-00-0, Group 1.
World Health Organization, Guidelines for Indoor Air Quality: Selected Pollutants (2010) — the 0.1 mg/m³ thirty-minute indoor air guideline for formaldehyde.
Competition and Consumer Commission of Singapore — administration of the Consumer Protection (Fair Trading) Act, under which absolute product claims require support.
CTI report A2250276330101001C, all seventeen results reproduced on our test report page.

About this article

Kopipets is a Singapore pet supplies brand for cats and dogs, operated by Surplus Media Pte. Ltd. (UEN 202448810R), a Singapore-registered company and the importer of record for the products we sell. We hold our own stock in a local warehouse, inspect it on arrival, and deliver islandwide with our own fleet.

This page was written by the Kopipets team and last checked on 31 July 2026. We will update it when we re-test, when the written binder specification arrives, or when a reader shows us we got something wrong. Corrections will be noted rather than quietly edited in.

Related reading: is tofu cat litter safe, and our honest buyer's guide to tofu cat litter in Singapore.