Persistent Organic Pollutant — chlorinated aromatic

Pentachlorobenzene in the bedroom

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

Pentachlorobenzene (PeCB) is a chlorinated aromatic compound — five chlorine atoms on a benzene ring, one short of its fully chlorinated relative hexachlorobenzene. It is a Stockholm Convention POP (Annex A and Annex C) and an EU SVHC. PeCB was historically used as a fungicide and as a flame retardant in combination with other chemicals, but its primary environmental source today is unintentional production as a by-product during the manufacture of chlorinated solvents and pesticides. Canada prohibits it under SOR/2025-270 (in force 30 June 2026).

Pentachlorobenzene — Embr Bedroom Chemistry Atlas

At a glance

Chemical familyChlorinated aromatic — environmental contaminant / legacy fungicide
CAS number608-93-5
ClassificationStockholm Convention Annex A (elimination) + Annex C (unintentional production); EU SVHC; EU POP Regulation; Canada SOR/2025-270 prohibited
Where you encounter itEnvironmental contaminant in dust and soil; by-product of chlorinated chemical manufacturing; legacy fungicide; by-product in some dye and pesticide production
Sleep micro-environment relevanceNot intentionally in any modern product — present as environmental persistence in dust, particularly near contaminated sites or in older buildings

Regulatory & certification status

European UnionPOP Regulation (EU) 2019/1021 — banned. SVHC (Candidate List). Listed under both Annex A (elimination of intentional production and use) and Annex C (minimisation of unintentional production). Regulatory — European Union authority
CanadaProhibited under the Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270), in force 30 June 2026. Limited exemption for use in servicing PCB-containing equipment. Regulatory — Canada authority
InternationalStockholm Convention Annex A (elimination) + Annex C (unintentional production). Listed in 2009. UNECE LRTAP Protocol on POPs. Regulatory — International authority
CertificationsOEKO-TEX Standard 100 screens for chlorinated benzenes as part of broader pesticide and chlorinated-compound testing. Industry

What it is

Pentachlorobenzene sits between tetrachlorobenzene and hexachlorobenzene in the chlorinated benzene series. It was once used as a fungicide and as a component in some flame-retardant formulations, but all deliberate uses have been eliminated under the Stockholm Convention. Like hexachlorobutadiene, its continued environmental presence is primarily from unintentional production during chlorinated chemical manufacturing. It is persistent, bioaccumulative, and toxic to aquatic organisms.

Where it shows up in bedding

PeCB does not appear in bedding products. Its bedroom relevance is as a persistent environmental contaminant in household dust — particularly in older homes, agricultural regions where chlorinated pesticides were used, and communities near chemical manufacturing or waste sites. Concentrations in typical urban household dust are very low, but detectable. PeCB is also a minor thermal decomposition product of some chlorinated flame retardants, providing a trace connection to treated materials.

Citations

  1. Stockholm Convention (2009). Listing of Pentachlorobenzene — Annex A and Annex C. Source Regulatory
  2. ECHA. Substance Information: Pentachlorobenzene. Source Regulatory
  3. Government of Canada. SOR/2025-270. Source Regulatory

Frequently asked questions

  • Is pentachlorobenzene different from pentachlorophenol?

    Yes. Despite similar names, they are different compounds. Pentachlorobenzene (PeCB, CAS 608-93-5) is a fully aromatic ring with five chlorines and no hydroxyl group. Pentachlorophenol (PCP, CAS 87-86-5) has a hydroxyl (-OH) group, making it a phenol — which is why PCP was used as a wood preservative and biocide. Both are POPs, but they have different uses, toxicity profiles, and regulatory histories.

  • Is PeCB a concern in my home?

    For most homes, no. PeCB concentrations in typical household dust are very low. The compound is primarily a concern near chemical manufacturing sites or in areas with heavy historical use of chlorinated pesticides. If you live near a contaminated site, check environmental monitoring data from your provincial or federal agency.

Related compounds

  • Hexachlorobenzene — the fully chlorinated benzene — same chemical series, IARC Group 1
  • Pentachlorophenol — the phenol analogue — a wood preservative, not the same compound
  • Lindane — another chlorinated POP persistent in household dust

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.