US EPA issues the proposed interim decision with recommended mitigation measures for TCVP

The U.S. Environmental Protection Agency (EPA) announced its Proposed Interim Decision (PID) for the pesticide tetrachlorvinphos (TCVP). The PID includes proposed mitigation measures for reducing human and environmental exposure to TCVP. EPA is also issuing a revised human health draft risk assessment (HH DRA). The PID, including the HH DRA, are open for public comment for 60 days.

TCVP is an organophosphate (OP) insecticide that is used to control fleas, ticks, lice, and flies in or on livestock animals and their facilities, pets, and garbage piles, and as a spot treatment in kennels, residential lawns, and recreational areas. In 2009, EPA received a petition from NRDC requesting that EPA cancel all pet uses of TCVP due to alleged health risks to humans. EPA initially denied NRDC’s petition on November 6, 2014. However, following litigation, the U.S. Court of Appeals for the Ninth Circuit issued an order on April 20, 2022, vacating EPA’s denial of NRDC’s petition and remanding it to EPA to issue a revised response by October 11, 2022.

On October 6, 2022, EPA issued a revised response to the NRDC petition, stating that it would begin drafting a proposed Notice of Intent to Cancel (NOIC) the use of TCVP in pet collars based on the identified risks of concern. EPA explained in that petition response, however, that the Agency expected the registrant to submit additional data that could change EPA’s risk assessment for the pet collar use, that EPA intended to incorporate into the drafting of the NOIC the review of any timely-received data, and that the Agency would not further pursue an NOIC if such data demonstrated that there is no longer a risk concern for any TCVP pet collars. Hartz, the registrant for TCVP pet products, gathered and submitted new data on potential human exposure from TVCP pet collars. These data included a new pet collar torsion study, which evaluated the amount of TCVP residues coming off of a collar when it is removed from a package, stretched, and placed on a cat or dog, and a revised fur clipping study, which assessed residues of TCVP found in an animal’s fur after the collar had been on the animal. EPA used the new data as part of its revised HH DRA and identified no human health risks of concern. Thus, EPA is no longer pursuing a Notice of Intent to Cancel (NOIC) for the TCVP pet collars and is announcing the issuance of its Determination Not to Further Pursue Cancellation of Tetrachlorvinphos (TCVP) Pet Collars, which may be found in the public docket at www.regulations.gov (Docket ID: EPA-HQ-OPP-2009-0308). The Determination Not to Further Pursue Cancellation of Tetrachlorvinphos (TCVP) Pet Collars – unlike the PID – is a final agency action that is not open for comment.

On August 30, 2023, EPA issued the document entitled Approach for Evaluating Developmental Neurotoxicity Potential for the Organophosphate Pesticides, which outlines EPA’s decision to evaluate the developmental neurotoxicity (DNT) potential of OPs to pregnant women and children on a chemical-by-chemical basis. This approach uses high quality, chemical-specific data from three primary lines of evidence: epidemiological studies, animal toxicity studies, and a battery of in vitro assays. These data are then used to evaluate DNT potential using a weight of evidence (WOE) approach, which is a process that integrates all relevant evidence to support decision-making that allows for consideration of strengths and limitations of each line of evidence. EPA does not have sufficient data to perform a WOE analysis to evaluate DNT potential to pregnant women and children using chemical-specific data for TCVP. As a result, the current assessment retains the Food Quality Protection Act Safety Factor that provides a 10-fold margin of safety for pregnant women and children.

The ecological draft risk assessment identified runoff—particularly from manure applications—as the primary route of exposure for aquatic non-target organisms. Acute and chronic risks were identified for birds (surrogates for reptiles and terrestrial-phase amphibians), mammals, and freshwater invertebrates. Although the database for honeybees is incomplete, risk estimates exceed the acute risk level of concern for adult bees from contact exposure.

The Agency is proposing a number of mitigation measures for the use of TCVP including prohibition of certain application methods, adoption of additional personal protective equipment, creation of nutrient management plans for livestock use, updates to disposal language on the label, and provision of enhanced reporting and sales data for TCVP pet products. EPA is also proposing ecological incident reporting language and Bulletins Live! Two labeling as interim ecological mitigation measures.

TCVP is still undergoing formal registration review, a process in which each registered pesticide is reviewed every 15 years to ensure that the pesticide can carry out its intended function(s) without unreasonable adverse effects to human health and the environment. The PID and supporting documents can be found in the public docket at www.regulations.gov (Docket ID: EPA-HQ-OPP-2008-0316).

View the Proposed Interim Decision.