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Tetrachlorvinphos (TCVP)

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Basic Information

Tetrachlorvinphos (TCVP) is an organophosphate (OP) insecticide used to control fleas, ticks, various flies, lice, and insect larvae on livestock and pets and their premises. TCVP is also applied as a perimeter treatment. TCVP is formulated into dusts, pet collars, emulsifiable concentrates, feed additives (solid and liquid), feed blocks, wettable powders, pellets and granular products. 

TCVP, when used on pets to protect from fleas and ticks, can have associated pet health risks when not used according to label instructions. Learn more about safely protecting pets from fleas and ticks.

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Using TCVP Products Safely

EPA’s 2016 risk assessment identified TCVP risks to people, including children, in residential settings from impregnated pet collars and TCVP dust/powder products and risks to workers applying TCVP.

We advise consumers to take certain precautions when handling TCVP products in residential areas.  These precautions are listed on TCVP product labels, including:

  • not allowing children to play with TCVP pet collar products
  • keeping TCVP spray and powder products out of reach of children, and
  • washing hands thoroughly with soap and water after handling.

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EPA Actions

TCVP was first registered as a pesticide in 1966. All crop uses of TCVP were voluntarily canceled in 1987. There are 18 tolerances (maximum residue limits) listed under 40 CFR § 180.252 (all are for animal products).

TCVP reregistration was initially completed via the September 1995 Reregistration Eligibility Decision (RED). Later EPA completed an interim tolerance reassessment eligibility decision in July of 2002 and in July of 2006 EPA issued the final TCVP RED following the completion of the organophosphate cumulative risk assessment. During the RED process, the EPA required registrants to update end-use product labeling to reduce potential risk associated with the use of TCVP products.

TCVP was one of the initial pesticide cases to be screened under the Endocrine Disruptor Screening Program. Based on this screening, EPA determined that it is not an endocrine disruptor, and additional data were not needed. 

EPA initiated the registration review process for TCVP in 2008.

In 2009, the EPA received a petition from the Natural Resources Defense Council (NRDC) to cancel all TCVP pet uses based on a human research study (Assessing Intermittent Pesticide Exposure From Flea Control Collars Containing the Organophosphorus Insecticide Tetrachlorvinphos (TCVP)” by M. Keith Davis, J. Scott Boone, John E. Moran, John W. Tyler and Janice E. Chambers).

In January 2016, EPA released preliminary human health and ecological risk assessments for public comment. The ecological risk assessment found that TCVP is very highly toxic to freshwater aquatic invertebrates, including a potential for acute and chronic risk to federally listed threatened and endangered (referred to as “listed”) and non-listed species of freshwater aquatic invertebrates for all of the registered uses of TCVP. Risk to listed and non-listed mammals, birds, reptiles, and terrestrial-phase amphibians also are possible. EPA’s response to comment received on the ecological risk assessment can be found in the docket.

In December 2016, EPA completed the final human health risk assessment for TCVP. Our human health assessment found risks of concern for:

  • people, including children, in residential settings exposed to dusts/powder products and pet collars; and
  • exposure to workers applying TCVP. 

In May 2017, EPA published an addendum to the human health risk assessment, as well as four responses to stakeholder comments on the human health risk assessment concerning:

EPA is working with product manufacturers to address these risks. Until that time, it is important to follow label instructions on proper use of pesticide products.

In July 2020, EPA denied NRDC’s 2009 petition to cancel all TCVP pet uses. As part of the Agency’s response to the petition, EPA released the Tetrachlorvinphos: Revised Residential Exposure Assessment for the Registered Pet Product Uses and Tetrachlorvinphos: Addendum to the Revised Residential Exposure Assessment for the Registered Pet Product Uses.

The Agency’s response to the petition, revised residential exposure assessment, and addendum will be available in the public docket for the NRDC petition in EPA-HQ-OPP-2009-0308 at The revised residential exposure assessment and addendum will also be available in the TCVP registration review docket EPA-OPP-HQ-2008-0316.

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Additional Information

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