Persistent Organic Pollutant — chlorinated pesticide

Hexachlorobenzene in the bedroom

By — 19-year firefighter and entrepreneur. Published July 2026.

Hexachlorobenzene (HCB) is a chlorinated aromatic compound classified as an IARC Group 1 human carcinogen and a Stockholm Convention persistent organic pollutant (POP). It was once used as a seed fungicide but is now banned globally for intentional production. The problem is persistence: HCB is a by-product of chlorinated solvent and dye manufacturing, a trace contaminant in some textile dyes, and it does not break down. It persists in household dust decades after its last deliberate use.

Hexachlorobenzene — Embr Bedroom Chemistry Atlas

At a glance

Chemical familyChlorinated pesticide / persistent organic pollutant (POP)
CAS number118-74-1
ClassificationIARC Group 1 (carcinogenic to humans); Stockholm Convention Annex A (elimination) and Annex C (unintentional production); EU POP Regulation; SVHC
Where you encounter itLegacy environmental contaminant in household dust; trace by-product in chlorinated dye and solvent production; historical fungicide on agricultural fibres
Sleep micro-environment relevanceNot intentionally added to any modern product — present as environmental persistence in dust and as trace contamination in some dyed textiles

Regulatory & certification status

European UnionPOP Regulation (EU) 2019/1021 — banned (production, use, placing on market). SVHC (Candidate List). REACH Annex XVII does not need a separate entry because the POP Regulation supersedes. Regulatory — European Union authority
United StatesEPA: cancelled all pesticide registrations. Listed as a hazardous air pollutant (Clean Air Act). California Proposition 65 listed (cancer). TSCA Inventory — no active commercial use. Regulatory — United States authority
CanadaProhibited under the Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270), which came into force 30 June 2026 — manufacture, use, sale and import are banned. Regulatory — Justice Laws
InternationalStockholm Convention Annex A (elimination) + Annex C (unintentional production). IARC Group 1. Basel Convention Annex I (hazardous waste). All 186 Parties to the Stockholm Convention are bound to eliminate HCB. Regulatory — International authority
CertificationsOEKO-TEX Standard 100 screens for chlorinated pesticides including HCB. Not typically a named limit in CertiPUR-US (foam-specific) since HCB is not a foam ingredient. Industry

What it is

Hexachlorobenzene is a fully chlorinated benzene ring — six chlorine atoms, maximum stability, maximum persistence. It was used as a seed-treatment fungicide from the 1940s until bans took effect from the 1970s onward. IARC classifies it as Group 1 (sufficient evidence of carcinogenicity in humans, based on porphyria cutanea tarda and liver effects in the exposed population of Southeastern Turkey in the 1950s–60s, plus animal evidence). The Stockholm Convention lists it under both Annex A (elimination of production and use) and Annex C (unintentional production by-product).

Where it shows up in bedding

HCB does not appear in modern bedding by design. Its relevance to the sleep environment is its sheer persistence: it is detectable in household dust worldwide decades after agricultural use ceased. It is also a trace by-product of chlorinated chemical manufacturing, including some textile dye intermediates — meaning dyed fabrics from uncontrolled supply chains could theoretically carry sub-ppm contamination. In practice, the primary bedroom exposure pathway is dust ingestion and inhalation, not direct textile contact.

The Embr Exposure Ledger: Hexachlorobenzene

One chemical, several public questions, answered from independent datasets and joined here — the environment it shows up in, the body burden it carries, how it is regulated, and what actually reduces it.

This compound appears in 6 of the Embr Exposure Ledger’s 10 exposure datasets.
Is it in the air?
In U.S. outdoor air: about 0.00026 in a million added lifetime cancer risk.Source: EPA AirToxScreen (2020) — modeled ambient air-toxics concentrations and risk
At what level would it matter?
Published benchmarks exist: a residential indoor-air screening level of 0.0061 µg/m³, set on a cancer endpoint (1-in-a-million excess lifetime risk). A screening level is the concentration at which EPA would look further, not a boundary between safe and harmful. The ledger holds no measured sleeping-environment concentration for this compound, so there is nothing here to compare the benchmark against — it tells you what would matter, not what is in any room.Source: US EPA, Regional Screening Levels (RSL) Summary Table — consolidated toxicity values from IRIS, PPRTV, ATSDR, Cal EPA and OPP
Who releases it?
54 US facilities reported releasing it in 2024 across 25 states and territories; 689 Canadian facilities have reported it (2000-2024). These are self-reported quantities leaving a facility, not levels anyone encountered, and the two national programs are not added together — they use different reporting thresholds.Source: US EPA, Toxics Release Inventory (TRI) Basic Data File, 2024 reporting year; Environment and Climate Change Canada, National Pollutant Release Inventory (NPRI), releases 1993-present
Does the law flag it?
Listed under California Proposition 65 for cancer, reproductive/developmental harm since 1987. Carries an EU-wide binding classification as carcinogenic (category 1B). That classifies the substance itself; it does not restrict any product. Banned in the EU under the persistent organic pollutants Regulation: manufacture, sale and use are prohibited. Specific exemptions apply.Source: California OEHHA Proposition 65 List (Safe Drinking Water and Toxic Enforcement Act of 1986)Source: EU CLP Annex VISource: EU POPs Regulation

Detection and body-burden figures are occurrence data, not a personal measurement or a health diagnosis. Part of the Embr Exposure Ledger — an open, cross-dataset chemical join (download the data), reusable with attribution.

Citations

  1. IARC (2001). Hexachlorobenzene. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 79. Source Regulatory
  2. Stockholm Convention. Listing of Hexachlorobenzene — Annex A and Annex C. Source Regulatory
  3. ECHA. Substance Information: Hexachlorobenzene. Source Regulatory

Frequently asked questions

  • Is hexachlorobenzene still used in products?

    No. HCB has been banned globally under the Stockholm Convention since 2004. It is not intentionally added to any consumer product. Its presence in the modern environment — including household dust — is entirely due to historical contamination, environmental persistence, and trace unintentional production as a by-product of other chlorinated chemical processes.

  • Why is a banned chemical still in household dust?

    Because HCB is extraordinarily persistent — it does not biodegrade readily, it binds to soil and dust particles, and it bioaccumulates. Agricultural soils treated with HCB decades ago still release it. Industrial sites that manufactured chlorinated chemicals still contaminate their surroundings. The dust in homes reflects the ambient environmental burden, which declines slowly over decades, not years.

Related compounds

  • PCBs — another Annex A and Annex C compound found in legacy building materials
  • Lindane (gamma-HCH) — another banned organochlorine pesticide persistent in dust
  • DDT — the defining Stockholm Convention POP, once sprayed on bedding
  • Pentachlorophenol — a chlorinated wood preservative and Stockholm POP
  • Hexachlorobutadiene — a fully chlorinated solvent by-product and Stockholm POP found in environmental samples
  • Pentachlorobenzene — the next chlorinated aromatic in the series; another Stockholm POP persistent in dust
  • Mirex — an original Stockholm "dirty dozen" organochlorine POP

Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.

Last reviewed 2026-07-07. If you find a factual error, contact us.