Persistent Organic Pollutant — organochlorine pesticide

Heptachlor in the bedroom

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

Heptachlor is a chlorinated cyclodiene insecticide used primarily for termite control and soil pest treatment from the 1950s through the 1980s. IARC classifies it as Group 2B (possibly carcinogenic). The Stockholm Convention lists it as an Annex A POP. Canada prohibits it under SOR/2025-270 (in force 30 June 2026). Like chlordane, heptachlor was applied directly to building foundations, and its breakdown product heptachlor epoxide persists in household dust and indoor air for decades after application.

Heptachlor — Embr Bedroom Chemistry Atlas

At a glance

Chemical familyOrganochlorine — cyclodiene insecticide
CAS number76-44-8
ClassificationIARC Group 2B (possibly carcinogenic to humans); Stockholm Convention Annex A (elimination); Canada SOR/2025-270 prohibited
Where you encounter itLegacy termite treatments in building foundations; household dust and indoor air in pre-1988 homes; food chain (dairy, meat); breaks down to heptachlor epoxide, which is more persistent
Sleep micro-environment relevanceNot in any modern product. Like chlordane, applied directly to foundations for termite control and persistent in indoor environments for decades. Heptachlor epoxide found in indoor air and dust

Regulatory & certification status

European UnionPOP Regulation (EU) 2019/1021 — banned. Original dirty dozen Stockholm POP. Regulatory
United StatesEPA cancelled virtually all uses (1988). CERCLA hazardous substance. California Proposition 65 listed (cancer). Regulatory
CanadaProhibited under the Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270), in force 30 June 2026. Regulatory — Canada authority
InternationalStockholm Convention Annex A (elimination) — original dirty dozen POP. IARC Group 2B (possibly carcinogenic). Regulatory — International authority

What it is

Heptachlor is a chlorinated cyclodiene insecticide named for its seven chlorine atoms. It was widely used for subterranean termite control and soil-insect treatment, often in combination with chlordane. In the environment, heptachlor converts to heptachlor epoxide — a more persistent, more bioaccumulative metabolite that retains biological activity. IARC classified heptachlor as Group 2B (possibly carcinogenic) based on sufficient evidence of carcinogenicity in animals (liver tumours) and inadequate evidence in humans. The combination of persistence, bioaccumulation, and possible carcinogenicity led to its inclusion in the Stockholm Convention dirty dozen.

Where it shows up in bedding

Heptachlor was not used in bedding products. Like chlordane and aldrin, it was applied to building foundations for termite control, creating a reservoir of contamination that can persist for decades. Heptachlor and its metabolite heptachlor epoxide have been detected in household dust and indoor air of treated homes years after application. During sleep, dust ingestion and inhalation contribute to exposure. Food-chain bioaccumulation (dairy, meat) is the primary exposure route for the general population.

The Embr Exposure Ledger: Heptachlor

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 4 of the Embr Exposure Ledger’s 10 exposure datasets.
Is it in the air?
In U.S. outdoor air: about 1e-06 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 0.0022 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?
19 US facilities reported releasing it in 2024 across 14 states and territories. 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 1988. Carries an EU-wide binding classification as carcinogenic (category 2). 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 (1991). Heptachlor. IARC Monographs Vol. 53. Source Regulatory
  2. ATSDR (2007). Toxicological Profile for Heptachlor and Heptachlor Epoxide. Source Regulatory
  3. Government of Canada. Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270). Source Regulatory

Frequently asked questions

  • What is heptachlor epoxide?

    Heptachlor epoxide is the primary breakdown product of heptachlor. It is more persistent and more bioaccumulative than the parent compound. Environmental monitoring for heptachlor contamination typically measures heptachlor epoxide because the parent compound converts relatively quickly. Both are regulated together under the Stockholm Convention.

  • How is heptachlor different from chlordane?

    Heptachlor and chlordane are closely related organochlorine insecticides — heptachlor is actually a component of technical-grade chlordane. Both were used for termite control, both persist in household dust, and both are dirty dozen Stockholm POPs. Chlordane was more widely used and is more commonly detected in indoor environments.

Related compounds

  • Chlordane — a related OCP often used alongside heptachlor for termites
  • Aldrin — another cyclodiene insecticide used for termite control
  • DDT — another original dirty dozen POP
  • Lindane — an organochlorine once applied directly to bedding

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.