What Canada Counts That the United States Doesn't

If you want to know what is being released into the environment near you, both countries have an answer. The United States runs the Toxics Release Inventory; Canada runs the National Pollutant Release Inventory. Facilities report what they released, the government publishes it, anyone can download it. Regulatory

We joined both registers to this site's compound atlas to see which of the chemicals that show up in mattresses and foam had release data behind them. The join covers 121 compounds: 97 with American data, 80 with Canadian, 56 with both. The interesting part was not the overlap. It was a short list of compounds that had Canadian data and no American data at all.

What Canada counts that the US does not

Five compounds stood out, because a facility in Canada has to report them and a facility in the United States does not. We checked each one against the EPA's published list of TRI-reportable chemicals for the 2024 reporting year rather than inferring absence from missing rows, because those are different things. Regulatory

Compounds reported to Canada's NPRI that do not appear on the EPA's RY2024 TRI chemical list. Canadian figures are cumulative across all reporting years.

Compound	Where it shows up	Canadian releases	Facilities	Years
Methyl ethyl ketone	Solvent in adhesives and coatings	76,091,390 kg	920	1993–2024
2-Butoxyethanol	Solvent in cleaners and coatings	16,810,704 kg	487	1999–2024
Benzyl butyl phthalate	Plasticiser, vinyl and foam backing	210,350 kg	51	1993–2024
DEHA	Plasticiser, flexible films	90,471 kg	58	1993–2024
BHT	Antioxidant in polyurethane foam	29,219 kg	17	1999–2023

The two large ones are solvents. Methyl ethyl ketone alone accounts for 76 million kilograms across 920 Canadian facilities, and an American facility releasing the same quantity of the same compound has no obligation to report it, because the EPA delisted it. The three smaller ones are more specific to this site's subject matter: two plasticisers and the antioxidant that goes into polyurethane foam to keep it from degrading.

BHT is the one worth pausing on. Twenty-nine tonnes across seventeen facilities is a rounding error next to the solvents, and it is the entry most directly tied to what a mattress is made of. It is on one national register and not the other.

A word on what this gap is not. It is not evidence that Canada is stricter. The reverse holds in several places — the American register carries a large PFAS category that the Canadian one only began phasing in for the 2025 reporting year, so on the compounds this site writes about most often, the US register is currently the better source. The two lists were built by different agencies, at different times, under different statutes, and neither was designed to answer “what goes into a mattress.” Inferred

The finding that did not survive

The first version of this piece had a better headline and it was wrong.

MDI — methylene diphenyl diisocyanate — is one of the two isocyanates that make polyurethane foam. Canada has release data for it: 1.3 million kilograms across 287 facilities in seven provinces. The American data had nothing. Meanwhile TDI, the other foam isocyanate, appeared in the American register 60 times. One isocyanate tracked, the other invisible, in the country that makes most of the continent's foam. That is a story.

It is also an artefact. MDI is on the TRI list. American facilities reported it 1,353 times in 2024 — more often than TDI — but under a category code, N120, covering twenty diisocyanates collectively rather than under its own CAS number. Our join is keyed on CAS numbers, so every one of those 1,353 reports fell straight through it.

This is the same failure we had already guarded against in the other direction. Canada reports most metals the same way: lead is filed as “NA - 08”, not as 7439-92-1, and a naive join drops every Canadian metal on the floor. We built a mapping for that case and did not think to check whether the Americans did the same thing with a different family of compounds. They do.

We have left the category codes unmapped rather than assigning them to a single compound, because N120 is genuinely twenty substances and pretending it is MDI would be a worse error than omitting it. The consequence is a real limit on the table above: it counts what each country files under a plain chemical identifier, and both countries file some things under category headings instead.

What a release figure is not

A release figure is a quantity a facility reported sending into the environment. It is not a concentration anyone encountered. Between the two sit distance, dilution, which medium it entered, and how long ago — and none of that is in either register.

The numbers above are also not comparable across the border, which is why this piece never adds them together. The two programmes use different reporting thresholds, cover different industries, and ask for different estimation methods. A combined North American total would describe two rulebooks rather than one measurement. Where a compound appears in both registers on the Exposure Ledger, the countries are kept in separate blocks for the same reason.

One more limit, and it is the one that matters most for anyone reading this in a bedroom: none of this says a compound released by a factory is the same molecule that ends up in a mattress. Industrial release data tells you a chemical is in active commercial use at scale, and where. It does not trace a path from a plant to a product to a person. That path is the interesting question and this dataset does not answer it.

What the register is good for is narrower and still useful. It tells you which of these compounds are genuinely current rather than historical. Diethyl phthalate last appeared in the Canadian data in 2012; short-chain chlorinated paraffins stopped in 2008; acetone, which was delisted on both sides of the border, stops in 1998. Methyl ethyl ketone and 2-butoxyethanol are still being reported in 2024. When a chemical shows up in a mattress discussion, that distinction is worth having.