Pesticide Registration

Pesticide Registration Manual: Chapter 8 - Inert Ingredients

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Inert Ingredients

Many pesticide products contain substances in addition to the active ingredient(s) that are referred to as inert ingredients or sometimes as “other ingredients.” This chapter describes how EPA reviews inert ingredients as part of the pesticide product review process. For the most recent information and updates on this process, see the Inert Ingredients Web page.

The Web page includes:

EPA plans to continue to post additional guidance and documents for inert ingredients on the Web page. Therefore, regular visits to the Web page are recommended.

Section 2(m) of FIFRA defines an inert ingredient as “an ingredient which is not active.” EPA further describes an inert ingredient in 40 CFR 152.3 as “any substance (or group of structurally similar substances if designated by the Agency), other than an active ingredient, which is intentionally included in a pesticide product, except as provided by 40 CFR 174.3.” Inert ingredients may be, for example, solvents, carriers, aerosol propellants, fragrances, and dyes.

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Regulation of Inert Ingredients

The registration and reregistration of pesticide products under FIFRA include a determination that the pesticide product formulation meets the registration standard under FIFRA section 3 (including the lack of unreasonable adverse effects on the environment). The entire formulation, including the inert ingredients, must meet this standard. In addition, the Federal Food, Drug, and Cosmetic Act (FFDCA) requires that inert ingredients in pesticide products used on food and feed crops, agricultural commodities, or livestock must have a tolerance or tolerance exemption under 40 CFR Part 180.

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Pesticide Product Registration and Inert Ingredients

Pesticide applicants who would like to use a chemical or substance as an inert ingredient in their pesticide product should first ensure that it has been approved by EPA. As part of the Agency’s review of an application for the registration of a pesticide product, the product’s composition information will be examined to verify that all of the inert ingredients proposed for use in the pesticide formulation have been approved by the Agency.

All Confidential Statements of Formula (CSF) submitted with a new or amended pesticide registration application for conventional pesticides, antimicrobial pesticides, and biopesticides are screened to ensure that all inert ingredients are approved for the labeled use of the pesticide formulation. If an inert ingredient is not currently approved for the intended use of the pesticide formulation and the application is covered by PRIA (FIFRA section 33) but does not contain the data necessary for the Agency to make a decision on the inert ingredient, then the submission will be rejected and a portion of the PRIA fee will be retained. A request for an inert ingredient approval should be communicated in the cover letter accompanying the application to assure efficient processing and as described in the Agency’s guidance.

If a new inert ingredient is part of an application for registration of a new conventional chemical product, the PRIA fee category will be R311 for a food use and R312 for nonfood use product. If a new conventional product is submitted and it requires an amendment to an existing inert tolerance exemption (e.g. adding post-harvest use) it will fall under the PRIA fee category R313. The only other category of pesticide application involving a request to approve an inert ingredient that is covered by PRIA is a request to approve a Plant Incorporated Protectant inert ingredient such as a marker protein with a fee category of B903.

The Agency’s current process for confirming the approval status of an inert ingredient included within other types of applications covered by PRIA are described in Footnote A of the 21 Day Content Screen Review Worksheet (PDF)(6 pp, 60 K). A request to approve an inert ingredient or to amend an inert ingredient tolerance exemption (excluding safeners) that is not associated with a pesticide registration application covered by PRIA will not have a mandatory time frame for the Agency’s review.

To avoid unnecessary delays, it is strongly recommended that applicants confirm the approval status of all components in their new product before submitting a registration application. Approved inert ingredient tolerances and tolerance exemptions are found in the Code of Federal Regulations (CFR) under 40 CFR Part 180. Inert ingredients approved for nonfood uses are listed on the Inert Ingredients Web page.

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New Inert Ingredients

Unless an inert ingredient is submitted under PRIA fee categories R311, R312, R313 or B903, approval of a use of a new inert ingredient should be obtained from the Agency prior to applying for a registration for a formulation containing the new inert ingredient to assure that the registration action can be efficiently processed by the Agency and to meet any PRIA mandatory due date. The inert ingredient approval process differs depending on whether the inert ingredient pesticide product will be used in pesticide products intended for food or nonfood use sites.

  • Approval for use of an inert ingredient in a nonfood-use pesticide product requires the submission of a request letter to EPA and supporting information. The request letter should include:

    • chemical name,
    • Chemical Abstracts Service (CAS) Registry Number of the inert ingredient, and
    • a description of the proposed use of the inert ingredient (i.e., purpose in formulation and use patterns of pesticide products that would contain the inert ingredient).

    Information typically used by the Agency to make a determination for a nonfood-use inert ingredient approval request includes:

    • physical/chemical properties,
    • toxicity data,
    • environmental fate and effects data, and
    • ecotoxicity data.

  • Based on the information provided on hazard, fate, and use pattern, EPA would approve the inert ingredient if the Agency did not expect that the ingredient would pose a significant risk to human health and the environment from inclusion in the pesticide product. Note, however, that risks associated with specific formulations are assessed individually. For more information on submitting a request for approval of a nonfood inert ingredient please see General Guidance for submitting a New Nonfood Use Inert Ingredient.
  • For an inert ingredient proposed for use in a food-use pesticide product, a petition for a tolerance or tolerance exemption must be submitted to EPA in accordance with 40 CFR 180.7. The petition should include a Notice of Filing and supporting information. The Notice of Filing must include:

    • chemical name,
    • CAS Registry Number of the inert ingredient,
    • the specific section of the CFR for which a tolerance/tolerance exemption is being sought (e.g., 40 CFR 180.920) or specific use pattern,
    • purpose in formulation (e.g., solvent, emulsifier, etc.), and
    • use limitations, if any.

    The supporting information that should be provided with the petition includes:

    • physical/chemical properties,
    • toxicity data,
    • environmental fate and effects data, and
    • ecotoxicity data.

    The Agency will evaluate all data and determine if the establishment of the tolerance/tolerance exemption will meet the FFDCA reasonable certainty of no harm safety standard prior to granting the tolerance/tolerance exemption. The inert ingredient will not be approved for food uses unless a tolerance or exemption is in effect. For more information on submitting a petition for a new food use inert ingredient please see General Guidance for submitting a New Food Use Inert Ingredient and Guidance to Petitioners for Low Risk Polymer Submission.

Individuals seeking additional information about either approval process should contact OPP’s Inert Ingredient Assessment Branch (

The Inert Ingredients Web page will include many useful resources, including:

  • helpful information about the approval processes,
  • tolerance reassessment documents,
  • newly established tolerances and exemptions, and
  • access to the list of approved inert ingredients.

EPA recommends that parties interested in establishing a tolerance exemption for a new inert ingredient first consult with the Agency, especially if they are considering embarking on a testing strategy. The consultation can be used to determine what information is available about the chemical and whether gaps in the data exist. Inert ingredient approval requests and other inert submissions should be submitted to the address in Chapter 21 with the distribution code (INERTS), and the cover letter should identify that it is an inert ingredient request to assure proper routing and processing.

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Inert Mixture Products

Pesticide applicants typically include individual inert ingredients in their pesticide products. In addition, applicants often purchase products containing a mixture of inert ingredients and add them to their pesticide products. For example, applicants may buy surfactants and anti-foaming agents made by other companies. These products may be mixtures containing multiple inert ingredients. Just as with individual inert ingredients, each component in a mixture must be approved for use by the Agency. It is the applicant’s responsibility to ensure that EPA has sufficient information about the inert mixture the applicant wishes to use.

When the composition of a mixture product is held as proprietary by the company that sells the mixture to the applicant, the Agency establishes a Master File for the mixture that contains the complete compositional information. If an applicant wishes to use a proprietary inert mixture as part of its product formulation, the following information should be submitted on the letterhead of the manufacturing company to the address in Chapter 21 with distribution code (INERTS) for each mixture (including proprietary mixtures):

  • The full product name and, for each component* in the mixture, its chemical name, CAS Registry Number, and percentage by weight.
  • The total percentage by weight for all components must total 100%.

Items submitted for inclusion in the Master File may be claimed as confidential business information (CBI). Information claimed as confidential will be treated in accordance with established procedures for handling FIFRA CBI. To assure proper routing and processing, the cover letter should identify the submission as inert ingredient mixture information.

*Please note - If the product contains a component that is itself a mixture or trade name product, EPA needs to receive the above information for all of the proprietary products. If there are impurities remaining in the final product, those components should be listed as such along with their percentage in the final formulation.

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Contacting the Inert Ingredient Assessment Branch

The staff of the Inert Ingredient Assessment Branch is available to assist you with your questions. The Branch’s e-mail address is: Inert Ingredient Assessment Branch (

Information is also available on the Inert Ingredients Web page.

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References Cited in Chapter 8

Refer to Chapter 19 for information on how to obtain these documents.

Code of Federal Regulation, Title 40

  • Part 152 - Pesticide Registration and Classification Procedures
  • Part 174 - Procedures and Requirements for Plant-Incorporated Protectants
  • Part 180 - Tolerances and Exemptions from Tolerances for Pesticide Chemicals in Food

Federal Insecticide, Fungicide, and Rodenticide Act, as amended by the Food Quality Protection Act of August 3, 1996

  • Section 2 Definition

Federal Food, Drug and Cosmetic Act

  • Section 408 - Tolerances and Exemptions for Pesticide Chemical Residues

Office of Pesticide Programs Inert Ingredients Web page.

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