Is Tetrachlorvinphos (TCVP) safe for dogs and cats?
Moderate risk for petsDogs are the primary animal subjects of TCVP exposure from flea collar use — TCVP flea collars for dogs (and cats) are the principal registered use of TCVP in the US. At label-directed flea collar use, acute toxicity to dogs is minimal given TCVP's low acute mammalian toxicity (rat oral LD50 ~4000 mg/kg). The primary concern for dogs is chronic dermal and potential oral exposure (licking collar areas) to TCVP and its breakdown products over the duration of collar use. TCVP inhibits AChE, but at collar wear levels the inhibition is not expected to produce clinical cholinergic signs. Cancer risk assessment for dogs from chronic collar use has not been conducted at the same depth as human health risk assessment; dogs' higher grooming rates and oral licking of collar-adjacent fur creates an ingestion pathway not typically modeled for humans. TCVP flea collars are not registered in the EU, where alternative collar formulations (deltamethrin, imidacloprid) are preferred. Veterinary guidance generally favors systemic flea prevention products (isoxazolines, spinosyns) over OP-containing collars for both efficacy and toxicological profile reasons.
What is tetrachlorvinphos (tcvp)?
The IUPAC name is [2-chloro-1-(2,4,5-trichlorophenyl)ethenyl] dimethyl phosphate.
Also known as: [2-chloro-1-(2,4,5-trichlorophenyl)ethenyl] dimethyl phosphate, Phosphoric acid, 2-chloro-1-(2,4,5-trichlorophenyl)ethenyl dimethyl ester, RefChem:862433, Caswell No. 217A.
- IUPAC name
- [2-chloro-1-(2,4,5-trichlorophenyl)ethenyl] dimethyl phosphate
- CAS number
- 961-11-5
- Molecular formula
- C10H9Cl4O4P
- Molecular weight
- 366.0 g/mol
- SMILES
- COP(=O)(OC)OC(=CCl)C1=CC(=C(C=C1Cl)Cl)Cl
- PubChem CID
- 13745
Risk for dogs
Moderate riskDogs are the primary animal subjects of TCVP exposure from flea collar use — TCVP flea collars for dogs (and cats) are the principal registered use of TCVP in the US. At label-directed flea collar use, acute toxicity to dogs is minimal given TCVP's low acute mammalian toxicity (rat oral LD50 ~4000 mg/kg). The primary concern for dogs is chronic dermal and potential oral exposure (licking collar areas) to TCVP and its breakdown products over the duration of collar use. TCVP inhibits AChE, but at collar wear levels the inhibition is not expected to produce clinical cholinergic signs. Cancer risk assessment for dogs from chronic collar use has not been conducted at the same depth as human health risk assessment; dogs' higher grooming rates and oral licking of collar-adjacent fur creates an ingestion pathway not typically modeled for humans. TCVP flea collars are not registered in the EU, where alternative collar formulations (deltamethrin, imidacloprid) are preferred. Veterinary guidance generally favors systemic flea prevention products (isoxazolines, spinosyns) over OP-containing collars for both efficacy and toxicological profile reasons.
Regulatory consensus
4 regulatory and scientific bodies have classified Tetrachlorvinphos (TCVP). The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| IARC | 1991 | Group 2B | IARC Group 2B for tetrachlorvinphos (TCVP), evaluated in Monograph 53 (1991) on occupational exposures in insecticide application and some pesticides. The classification is based on sufficient evidence of carcinogenicity in experimental animals — hepatocellular carcinomas in mice and adrenal pheochromocytomas in rats in NTP chronic bioassays — and limited evidence in humans from occupational cohort studies. TCVP is a vinylphosphate organophosphate with AChE-inhibiting activity; it is structurally related to chlorfenvinphos and dichlorvos (DDVP). TCVP has low acute mammalian toxicity (rat oral LD50 approximately 4000–5000 mg/kg) relative to other OPs. It remains registered in the US primarily in pet flea collar formulations (Hartz, Sergeant's brands), where its low acute toxicity was considered to provide a safety margin for consumer use. NRDC petitioned EPA in 2009 to cancel TCVP in pet products based on the IARC 2B classification and carcinogenic animal bioassay data; EPA reviewed this petition and issued a preliminary risk assessment in 2016 finding that cancer risks from TCVP flea collar use exceeded acceptable levels for children in some scenarios. The petitioned cancellation of TCVP flea collars remained unresolved as of 2025 as EPA continued its registration review. IARC has not re-evaluated since 1991. |
| EPA CTX / EPA OPP | — | Likely to be Carcinogenic to Humans | |
| EPA CTX / Genetox | — | Genotoxicity: negative (Ames: negative, 0 positive / 1 negative reports) | |
| EPA CTX / Genetox | — | Genotoxicity: negative (Ames: negative, 0 positive / 1 negative reports) |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where pets encounter tetrachlorvinphos (tcvp)
- Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
- Occupational Environments — Factories, Warehouses, Transportation vehicles
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Tetrachlorvinphos (TCVP):
-
Spinosad; Bt; Neem; Beneficial insects; Physical barriers
Trade-offs: Species-specific; no chemical residues; self-sustaining once established; slow onset (weeks vs hours for chemicals); requires ecological knowledge; may not achieve complete control; compatible with organic certification.Relative cost: 1.2-2×
Frequently asked questions
Is tetrachlorvinphos (tcvp) safe for pets?
Dogs are the primary animal subjects of TCVP exposure from flea collar use — TCVP flea collars for dogs (and cats) are the principal registered use of TCVP in the US. At label-directed flea collar use, acute toxicity to dogs is minimal given TCVP's low acute mammalian toxicity (rat oral LD50 ~4000 mg/kg). The primary concern for dogs is chronic dermal and potential oral exposure (licking collar areas) to TCVP and its breakdown products over the duration of collar use. TCVP inhibits AChE, but at collar wear levels the inhibition is not expected to produce clinical cholinergic signs. Cancer risk assessment for dogs from chronic collar use has not been conducted at the same depth as human health risk assessment; dogs' higher grooming rates and oral licking of collar-adjacent fur creates an ingestion pathway not typically modeled for humans. TCVP flea collars are not registered in the EU, where alternative collar formulations (deltamethrin, imidacloprid) are preferred. Veterinary guidance generally favors systemic flea prevention products (isoxazolines, spinosyns) over OP-containing collars for both efficacy and toxicological profile reasons.
What products contain tetrachlorvinphos (tcvp)?
Tetrachlorvinphos (TCVP) appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).
Why do regulators disagree about tetrachlorvinphos (tcvp)?
Tetrachlorvinphos (TCVP) has been classified by 4 agencies including IARC, EPA CTX / EPA OPP, EPA CTX / Genetox, EPA CTX / Genetox, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
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Open in pets View raw API dataSources (2)
- IARC Monographs Volume 53: Occupational Exposures in Insecticide Application and Some Pesticides — Tetrachlorvinphos Group 2B Classification, Mouse Liver Tumors, and NTP Bioassay Data (1991) (1991) — regulatory
- US EPA: Tetrachlorvinphos (TCVP) Registration Review — IARC 2B Classification, Pet Flea Collar Petting Pathway, Children's Cancer Risk, and NRDC Petition Response (2016) (2016) — regulatory
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →