At a glance
| Chemical family | Organochlorine acaricide (miticide), manufactured from technical DDT |
| CAS number | 115-32-2 (p,p′-dicofol; the o,p′-isomer is 10606-46-9) |
| Classification | IARC Group 3 — not classifiable as to its carcinogenicity to humans; Stockholm Convention POP (Annex A, elimination, no exemptions) |
| Where you encounter it | Sprayed on cotton, citrus, apples, tea, vegetables and ornamentals, and on non-residential lawns. Documented human exposure is through food, milk and breast milk. It has never been used in any indoor, textile or bedding product. |
| Sleep micro-environment relevance | Low and unmeasured. The only plausible indoor route is soil residue tracked in on shoes, and no published study has quantified dicofol in house dust, carpet or bedding. |
Regulatory & certification status
Where dicofol stands across the major regulatory systems. Each row names the governing instrument; where a jurisdiction has no specific measure, or where we could not verify one from a primary source, that is stated plainly rather than left blank.
| International | Listed in Annex A of the Stockholm Convention (elimination) by decision SC-9/11 at the ninth Conference of the Parties, 29 April to 10 May 2019. The exemption columns read “Production: None. Use: None.” The scientific basis is the POPRC-12 risk profile adopted in September 2016. Regulatory — Stockholm Convention Secretariat |
| European Union | Banned. Dicofol is listed in Annex I Part A of Regulation (EU) 2019/1021, the POPs Regulation, at CAS 115-32-2 / EC 204-082-0 with the specific-exemption column reading “None”. Annex I prohibits manufacture, placing on the market and use. This is a genuine ban, unlike the REACH Candidate List, which only identifies a substance, or a CLP entry, which only communicates hazard. Dicofol was already a non-approved active substance under the plant-protection regime before the POPs listing. Regulatory — Regulation (EU) 2019/1021 Annex I Part A |
| European Union — CLP | A harmonised classification exists at index 603-044-00-4: Acute Tox. 4 (H302, oral), Acute Tox. 4 (H312, dermal), Skin Irrit. 2 (H315), Skin Sens. 1 (H317), Aquatic Acute 1 (H400) and Aquatic Chronic 1 (H410), with pictograms GHS07 and GHS09 and the signal word Warning. There is no harmonised carcinogenicity, mutagenicity, reproductive-toxicity or endocrine-disruptor entry. That absence is not an absence of hazard: Annex VI covers only the subset agreed at EU level, and everything outside it is industry self-classification. The endocrine evidence summarised in the POPRC risk profile sits entirely outside the harmonised entry. Regulatory — CLP Annex VI Table 3 |
| United States | All registrations were voluntarily cancelled. Under a Memorandum of Agreement with EPA dated 17 May 2011, production ceased that day; the technical-product cancellation took effect 14 December 2011 and end-use cancellations on 31 October 2013; labels prohibited use after 31 October 2016, and EPA revoked the food tolerances from the same date. EPA called dicofol the last organochlorine pesticide to go through a cancellation process terminating all remaining US uses. It is not listed under California Proposition 65 and not listed in the NTP 15th Report on Carcinogens. The EPA IRIS file was archived on 10 December 2018 with cancer weight-of-evidence “information reviewed but value not estimated” and no reference dose. Regulatory — US EPA cancellation order; EPA IRIS (archived); NTP 15th Report on Carcinogens; OEHHA Proposition 65 list |
| Canada | Use has not been permitted since 2011, as recorded in the Stockholm Convention risk profile. Dicofol does not appear in the Prohibition of Certain Toxic Substances Regulations, 2025 (SOR/2025-270) — verified by full-text search of the Canada Gazette Part II publication of 31 December 2025, with no match on name or CAS in the regulations, schedules or regulatory impact statement. The reason is structural: dicofol was controlled as a pest control product under the Pest Control Products Act rather than added to CEPA Schedule 1, so several related organochlorines in this Atlas carry that prohibition and dicofol does not. Whether Canada has formally accepted the SC-9/11 amendment was not confirmed from a primary source here. Regulatory — POPRC-12 risk profile; SOR/2025-270 (absence verified) |
| United Kingdom | Annex I Part A of Regulation (EU) 2019/1021 was retained in Great Britain, carrying the same row: dicofol, CAS 115-32-2, EC 204-082-0, specific exemption “None”. Manufacture, placing on the market and use are therefore prohibited in GB. Regulatory — legislation.gov.uk retained EU law |
| Australia | Not established here, and we will not guess. Dicofol is an agricultural and veterinary chemical regulated by the APVMA rather than an industrial chemical, so the IChEMS Register and its Schedule 7 prohibition mechanism do not apply to it. The NHMRC Australian Drinking Water Guidelines carry a health-based value: dicofol in drinking water should not exceed 0.004 mg/L. That same guideline page still refers to registered products and cites the 2010 poisons standard, which makes it stale evidence of current registration and unusable for that purpose. The POPRC risk profile records Australia among countries applying a 0.1% limit on the ΣDDT (total DDT-related) content of commercial dicofol. Current APVMA status and Australia's acceptance of SC-9/11 are open. Regulatory — NHMRC Australian Drinking Water Guidelines |
What it is
Dicofol is an organochlorine acaricide, sold from the mid-1950s under names including Kelthane to kill spider mites on crops. It is made from the pesticide it most resembles: the Stockholm Convention risk profile states that dicofol “has been manufactured from technical DDT by hydroxylation of DDT”, and commercial material carries DDT and DDT breakdown products as impurities. Regulatory — POPRC-12 risk profile
Technical dicofol is not one molecule but two. The risk profile records it as “80-85% p,p′-dicofol and 15-20% o,p′-dicofol with a reported variation range of DDT and other impurities”. CAS 115-32-2, the number on this page, denotes the p,p′ form; the o,p′ isomer has its own registry number, 10606-46-9. Any statement about “dicofol” in a monitoring study is a statement about a mixture.
IARC evaluated dicofol in Volume 30 (1983) and placed it in Group 3, not classifiable as to its carcinogenicity to humans, an assignment carried forward in Supplement 7 (1987). The working group found that results in mice provided limited evidence of carcinogenicity in experimental animals, judged the rat study inadequate, and had no human epidemiological data to work with. Regulatory — IARC Monographs Vol. 30 / Suppl. 7
Where it shows up
On crops, not in products
Dicofol was applied to cotton, citrus, apples, tea, vegetables and ornamentals, mainly in East and Southeast Asia, around the Mediterranean, and in Northern and Central America. EPA's registered US uses were “as a miticide on cotton and several other agricultural crops and on non-residential lawns and ornamentals”. Regulatory — US EPA 2011 cancellation order It was never a foam additive, a fibre-fill treatment, a cover-fabric finish or a flame retardant, and there is no record of it being used against house dust mites. The mites it was sold to kill were spider mites on a cotton plant, not the ones living in a bed.
The one route into a home is soil on shoes
Dicofol reaches an indoor space the way every legacy organochlorine does: as residue in outdoor soil, tracked in on footwear and settling into carpet and floor dust. It has been measured in agricultural surface soil and in dated lake-sediment layers going back to the 1940s, so the outdoor reservoir is real. Regulatory — POPRC-12 risk profile The step from that reservoir to a bedroom floor is the same step that puts DDT and dieldrin in house dust, and it is an inference from compound class rather than a dicofol measurement. Inferred — track-in pathway reasoned from the compound class, not measured for dicofol
The measurement nobody has made
No published study has quantified dicofol in house dust, carpet dust, bedding or residential indoor air. The 42-page international assessment that got dicofol banned contains the word “indoor” zero times, and “dust”, “carpet” and “textile” zero times each. Its human-exposure section is entirely about food: milk, baby formula, eggs, fruit, vegetables and breast milk. The closest thing to indoor evidence is indirect. A 2020 survey of European domestic air reported that “ΣHCHs, ΣDDXs and ΣPBDE levels mirrored lindane, dicofol and Penta-, DecaBDE use, respectively” — the authors attributed part of the measured DDT-related burden to past dicofol use, but dicofol itself was not among the compounds they quantified. Peer-reviewed — de la Torre et al. 2020
What the research says
- It is still in people, decades after the spraying stopped. In an adult cohort in southern Spain, “OCPs were detected in 84.2% (β-HCH), 21.7% (α-HCH), and 19.6% (dicofol) of the population” — about one adult in five carried detectable dicofol in adipose tissue. The exposure that put it there was diet and proximity to treated land, not bedding. Peer-reviewed — Salcedo-Bellido et al. 2022
- IARC Group 3, on thin evidence in both directions. Limited evidence in mice, an inadequate rat study, no human data. Group 3 means the question was not answerable, not that the answer was no. Regulatory — IARC Vol. 30 (1983), Suppl. 7 (1987)
- Negative results deserve a caveat. Dicofol is chemically unstable in solution and hard to analyse. The risk profile notes that appropriate analytical methods were lacking as of 2011 and that data reported before then may be less sensitive, so a “not detected” in an older study is weak evidence of absence. Regulatory — POPRC-12 risk profile
- There is no dose benchmark to compare anything against. Dicofol has no published inhalation reference value. Its EPA IRIS file was archived in 2018 with no reference dose and no cancer value derived, it does not appear in EPA's Regional Screening Level summary table as we hold it, and EFSA concluded in 2023 that “the existing toxicological reference values derived at the EU level cannot be confirmed for dicofol”. Presence is not dose, and here we have neither. This is a clean case of the pattern we count in The Dose Gap. Regulatory — EFSA 2023; EPA IRIS (archived)
What helps
Take your shoes off at the door. Track-in from soil is the only documented route by which an agricultural organochlorine reaches a home, and dicofol has been measured in farmed surface soil. This is generic legacy-pesticide hygiene rather than dicofol-specific advice, and it is worth doing for the whole class at once.
Vacuum with a sealed HEPA machine and damp-wipe hard floors. Settled dust is the indoor reservoir for every legacy organochlorine, and dry sweeping puts it back in the air. No study has measured dicofol in house dust, so this reasoning comes from the compound class, not from a dicofol number.
Pay attention to the land, not the bed. If a home sits on or beside ground with a cotton, citrus, apple, pear or tea history, the soil and the entryway are the parts worth attention.
Think about food before furniture. The evidence that exists points at diet. The Stockholm risk profile's whole human-exposure section is food, milk, eggs and breast milk, and the one human body-burden study available found detectable dicofol in about one adult in five in an agricultural region. Anyone genuinely concerned about their own dicofol exposure should be thinking about produce sourcing.
What does not help
- Replacing the mattress. Dicofol has never been a foam, latex, fibre-fill, cover-fabric or flame-retardant chemical. There is no mattress source to remove.
- Buying an air purifier for this compound. There is no published indoor-air concentration of dicofol to reduce. The one European domestic-air study connected to it measured DDT-related compounds and inferred a dicofol contribution; dicofol itself was not quantified.
- Trusting an “organic” or “non-toxic” bedding label to mean anything here. Those labels describe what went into the product. Dicofol, if it is present at all, arrives as soil dust on the soles of shoes.
- Reading ingredient lists for it. All EU, UK, US and Canadian use has ended, so a currently sold product will not contain it. The question is residue, not ingredient.
- Buying an encasement on dicofol's account. It is an acaricide, but an agricultural one aimed at crop spider mites. Encasements earn their money against house dust mite allergen, a different problem with its own evidence base.
Open research questions
- No published house-dust, carpet-dust or bedding measurement of dicofol was found. Searches across dicofol combined with house dust, indoor dust, settled dust, carpet dust, floor dust and indoor air returned no study quantifying it in a residential matrix. A single such measurement would change the central claim of this page. Speculation
- Australia's current position is unresolved. The drinking-water guideline value of 0.004 mg/L is verified, but the same guidance still refers to registered products and cites the 2010 poisons standard, and neither the current APVMA registration status nor Australia's acceptance of the SC-9/11 amendment was established from a primary source. Speculation
- Whether Canada has formally accepted the SC-9/11 listing is unverified. What is verified is narrower: use has not been permitted since 2011, and dicofol is absent from SOR/2025-270. Speculation
- How much of the DDT-related burden measured in European domestic air is attributable to past dicofol use rather than to DDT applied as DDT. The 2020 study attributes a share without separating the two sources. Speculation
The exposure ledger for Dicofol
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.
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.
Where you meet Dicofol across your home
The same compound turns up in more than one place you live. Here's where it shows up in Embr — each links to the full breakdown for that part of your home.
Citations
- Persistent Organic Pollutants Review Committee (2016). Risk profile on dicofol (UNEP/POPS/POPRC.12/11/Add.1). United Nations Environment Programme / Stockholm Convention Secretariat. PDF Regulatory
- Secretariat of the Stockholm Convention (2019). The new POPs under the Stockholm Convention — Dicofol (decision SC-9/11). United Nations Environment Programme. pops.int Regulatory
- European Parliament and Council of the European Union (2019). Regulation (EU) 2019/1021 on persistent organic pollutants, Annex I Part A, as retained in Great Britain. legislation.gov.uk (The National Archives). Annex I Regulatory
- European Chemicals Agency (2008). Annex VI to Regulation (EC) No 1272/2008 (CLP), Table 3 — harmonised classification and labelling, index 603-044-00-4 (dicofol). Official Journal of the European Union. CELEX:32008R1272 Regulatory
- International Agency for Research on Cancer Working Group (1983). Dicofol. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 30 (Miscellaneous Pesticides), with subsequent evaluation in Supplement 7 (1987), p. 62. IARC / WHO. IPCS INCHEM Regulatory
- United States Environmental Protection Agency, Office of Pesticide Programs (2011). Dicofol; Cancellation Order for Certain Pesticide Registrations. EPA archive Regulatory
- European Food Safety Authority (2023). Targeted review of maximum residue levels (MRLs) for dicofol. EFSA Journal 21(11). DOI: 10.2903/j.efsa.2023.8425 Regulatory
- Torre, A. de la, Sanz P, Navarro I, Martínez M.L.Á. (2020). Investigating the presence of emerging and legacy POPs in European domestic air. Science of The Total Environment 746:141348. DOI: 10.1016/j.scitotenv.2020.141348; PMID 32750573. Peer-reviewed
- Salcedo-Bellido I, Amaya E, Pérez-Díaz C, Soler A, Vela-Soria F, Requena P, Barrios-Rodríguez R, Echeverría R, Pérez-Carrascosa FM, Quesada-Jiménez R, Martín-Olmedo P, Arrebola JP (2022). Differential Bioaccumulation Patterns of α, β-Hexachlorobenzene and Dicofol in Adipose Tissue from the GraMo Cohort (Southern Spain). International Journal of Environmental Research and Public Health 19:3344. DOI: 10.3390/ijerph19063344; PMID 35329028. Reproduced as published: the title says “Hexachlorobenzene” where the paper's abstract and content say hexachlorocyclohexane (HCH). Peer-reviewed
Frequently asked questions
Was dicofol ever used in mattresses or bedding?
No. EPA described dicofol's registered uses as a miticide on cotton and several other agricultural crops and on non-residential lawns and ornamentals. It was never a foam additive, a fibre treatment, a cover-fabric finish or a flame retardant, and it was never applied to bedding. Because all EU, UK, US and Canadian uses have ended, a product sold today will not contain it.
Could dicofol be in my house dust?
Nobody has published a measurement of dicofol in house dust or bedding. The 42-page Stockholm Convention risk profile that led to the global ban does not mention indoor air, dust, carpet or textiles anywhere; its entire human-exposure section is food, milk, eggs and breast milk. Dicofol has been measured in agricultural surface soil, so track-in on shoes is a plausible route by analogy with other legacy organochlorines. That is a pathway argument, not a measurement, and the page treats it as one.
Is dicofol a carcinogen?
IARC places dicofol in Group 3, not classifiable as to its carcinogenicity to humans. Volume 30 (1983) recorded limited evidence in experimental animals, an inadequate rat study and no human epidemiological data; the Group 3 assignment was carried forward in Supplement 7 (1987). The EU harmonised classification covers acute oral and dermal toxicity, skin irritation, skin sensitisation and aquatic hazard, with no harmonised carcinogenicity, mutagenicity or reproductive-toxicity entry. Annex VI covers only the subset agreed at EU level, so absence from it is not the same as absence of hazard.
Is dicofol still legal anywhere?
Dicofol was listed in Annex A of the Stockholm Convention by decision SC-9/11 in 2019, with no specific exemptions for production or use. In the EU it sits in Annex I Part A of Regulation (EU) 2019/1021, so manufacture, placing on the market and use are prohibited, and that prohibition was retained in Great Britain. US use was prohibited after 31 October 2016 and Canadian use has not been permitted since 2011. Status in countries that have not yet given effect to the listing was not established here.
Related compounds
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Last reviewed 2026-07-25. If you find a factual error, contact us.