At a glance
| Chemical family | Chlorinated solvent (volatile) — used as an auxiliary blowing agent in flexible polyurethane foam |
| CAS number | 75-09-2 |
| Classification | NTP — reasonably anticipated to be a human carcinogen; IARC Group 2A (probably carcinogenic to humans); EPA IRIS — likely to be carcinogenic to humans; EPA 2024 TSCA rule prohibits most consumer and many commercial uses |
| Where you encounter it | Historically: paint and varnish strippers, degreasers, adhesives, extraction solvents, and as a foam blowing agent; most consumer uses are now restricted in the US |
| Sleep micro-environment relevance | An auxiliary blowing agent used to make some flexible foam (trace residual possible); broadly an indoor-air solvent VOC where methylene-chloride products are used in the home |
| Activated carbon capture | Moderate — a small volatile chlorinated molecule; adsorbs onto activated carbon but with limited capacity relative to larger compounds |
What it is
Methylene chloride is a colorless, volatile, sweet-smelling chlorinated solvent. It dissolves a wide range of materials, which made it a workhorse paint stripper, degreaser, and extraction solvent for decades. In foam manufacturing, it served as an auxiliary blowing agent: added to the polyurethane mix, it vaporizes and helps the foam expand and soften, supplementing the carbon dioxide generated by the water–isocyanate reaction. It rose in popularity as a foam blowing agent when the ozone-depleting CFCs it partly replaced came under restriction. Regulatory — EPA flexible PU foam NESHAP
Its toxicology is serious on two fronts. It is a carcinogen — the U.S. National Toxicology Program lists dichloromethane as reasonably anticipated to be a human carcinogen, IARC classifies it as Group 2A (probably carcinogenic to humans), and EPA's IRIS assessment calls it likely to be carcinogenic. Regulatory — NTP, EPA IRIS Peer-reviewed — IARC Group 2A And it is acutely dangerous: it is a central-nervous-system depressant, and the body metabolizes it to carbon monoxide, so using it in a poorly ventilated space can cause fatal carbon-monoxide poisoning. Deaths during bathtub refinishing and paint stripping led the EPA, in 2024, to finalize a rule banning most consumer and many commercial uses. Regulatory — EPA 2024 TSCA rule
How it relates to the bedroom
An auxiliary foam blowing agent
Where methylene chloride was used to blow flexible foam, trace residual solvent could remain in the product. Its use has been heavily regulated and reduced over time, and the EPA's flexible-polyurethane-foam standards specifically targeted methylene-chloride emissions from foam fabrication. So while it belongs in any honest account of "what makes foam," it is a declining and largely manufacturing-side part of that story rather than a major finished-mattress exposure. Inferred — residual methylene chloride in finished consumer foam is low and declining; not a documented significant sleeper exposure
An indoor-air solvent
The more consequential bedroom-adjacent exposure has historically been from using methylene-chloride products in the home — paint strippers, adhesives, and aerosols — in poorly ventilated rooms. This is an acute, use-driven exposure, not a passive emission from furnishings, and it is exactly the scenario the 2024 EPA restrictions target. Regulatory — EPA
Why the honest framing matters
Methylene chloride is genuinely dangerous, but the danger is concentrated in solvent products used in enclosed spaces — not in a cured mattress. Conflating the two would misdirect concern. The mattress relevance is the foam-blowing history and the broader indoor-air-solvent context; the acute risk is the stripper in the unventilated bathroom.
What the research says
Carcinogenicity
The carcinogen classifications are consistent across agencies: NTP (reasonably anticipated), IARC (Group 2A), and EPA (likely to be carcinogenic). Regulatory — NTP, EPA Peer-reviewed — IARC The animal evidence is sufficient and the mechanistic case (genotoxic metabolites) is established; human epidemiology is more limited, consistent with a "probable/likely" rather than "known" rating.
Acute carbon-monoxide toxicity
The metabolism of methylene chloride to carbon monoxide is well documented and is what makes enclosed-space exposure lethal: carboxyhemoglobin forms in the blood, reducing oxygen delivery, exactly as in carbon-monoxide poisoning. Regulatory — ATSDR This acute pathway, plus the carcinogenicity, is why regulators moved against it.
What helps reduce exposure
Do not use methylene-chloride paint strippers or solvents indoors. This is the real, controllable risk. Most consumer products have been restricted in the US as of 2024; if you have old stock, do not use it in enclosed spaces — safer stripping alternatives exist.
Air out and ventilate new foam. For any trace residual blowing-agent solvent, the standard early-life airing and bedroom ventilation apply.
Ventilate during and after any solvent or renovation work near sleeping areas, and keep such products out of the bedroom entirely.
Activated-carbon filtration adsorbs methylene chloride moderately as part of the broader VOC mixture, though for this compound source-control (not using the products) is far more important than filtration.
What does NOT help
- Treating the mattress as the methylene-chloride risk. The acute danger is solvent products in enclosed spaces; finished foam is not a documented significant source.
- Relying on smell as a warning. Methylene chloride has a mild, even pleasant odor and depresses the senses; odor is not a reliable indicator of dangerous concentration.
- HEPA-only air purifiers. Methylene chloride is a gas; particle filtration does not remove it.
Open research questions
- Residual methylene-chloride content and emission from foam historically blown with it, under in-use conditions. Speculation
- The degree to which the 2024 EPA restrictions reduce real-world indoor methylene-chloride exposure over time. Speculation
Citations
- NTP. 15th Report on Carcinogens — Dichloromethane (reasonably anticipated to be a human carcinogen). Regulatory
- IARC. Dichloromethane — Group 2A (probably carcinogenic to humans). Peer-reviewed
- EPA. IRIS — Dichloromethane (likely to be carcinogenic to humans); 2024 TSCA risk-management rule restricting most uses. Regulatory
- ATSDR. Toxicological Profile for Methylene Chloride. Regulatory
- EPA. Flexible Polyurethane Foam Production and Fabrication NESHAP — methylene chloride as auxiliary blowing agent. Regulatory
Frequently asked questions
What is methylene chloride used for?
Methylene chloride (dichloromethane) is a volatile chlorinated solvent. It has been used as a paint and varnish stripper, a degreaser, an extraction solvent, and — relevant here — as an auxiliary blowing agent in flexible polyurethane foam manufacturing, where it helps the foam expand. It is an NTP- and IARC-listed carcinogen, and in 2024 the EPA finalized a rule restricting most of its uses.
Is methylene chloride in my mattress?
Methylene chloride was used as an auxiliary blowing agent in some flexible-foam manufacturing, so trace residual solvent could be present in foam made that way — but its use has been heavily regulated and reduced, and finished cured foam is not a documented significant source of methylene chloride exposure for sleepers. The serious acute dangers come from using methylene chloride products like paint strippers in enclosed spaces, not from a mattress.
Why is methylene chloride dangerous?
It is a carcinogen — NTP lists it as reasonably anticipated to be a human carcinogen and IARC classifies it as Group 2A, probably carcinogenic. It is also acutely dangerous: it depresses the central nervous system, and the body converts it to carbon monoxide, so using it in poorly ventilated spaces has caused fatal carbon-monoxide poisonings, especially during bathtub refinishing and paint stripping. The EPA banned most consumer and many commercial uses in 2024.
Did the EPA ban methylene chloride?
In 2024 the EPA finalized a rule under the Toxic Substances Control Act prohibiting most consumer uses and many commercial uses of methylene chloride, after documented deaths from paint-stripping exposures. Some industrial uses continue under a strict workplace-protection program. This is one of the clearer recent examples of a widely used chemical being restricted on health grounds.
How does methylene chloride make carbon monoxide?
Once inhaled, methylene chloride is metabolized in the liver, and one pathway produces carbon monoxide, which binds hemoglobin as carboxyhemoglobin and reduces the blood's oxygen-carrying capacity. This is why methylene chloride poisoning can resemble carbon-monoxide poisoning and why enclosed-space use is so hazardous.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-06-27. If you find a factual error, contact us.