Categorized Lists of Inert Ingredients (Old Lists)

For an inert ingredient to be included in a food-use pesticide product, a tolerance exemption must be established in the appropriate section of 40 CFR 180 subpart D.

InertFinder provides current information on tolerances and tolerance exemptions for inert ingredients.

The following information is provided as a resource related to regulations that refer to chemicals by these lists. We no longer update these lists.

Categorized Lists

OPP published a policy statement on inert ingredients in 1987: 52 FR 13305, Inert Ingredients in Pesticide Products Policy Statement (04/22/87). The policy established four categories of toxicological concern for the inert ingredients in existence at that time. In 1989, List 4 "Inerts of Minimal Concern" was subdivided into List A and List 4B (see 54 FR 48314, Inert Ingredients in Pesticide Products; Policy Statement; Revision and Modification List (11/22/89)).

The List Category policy, created in 1987, has now served its purpose as a tool for prioritizing the evaluation of chemicals. Now that reassessment of food tolerances/tolerance exemptions under the Food Quality Protection Act (FQPA) is complete, inerts are no longer classified as List 1, 2, or 3.

Regarding List 4:

  • All-food use inert ingredient tolerances and tolerance exemptions are considered to be safe when used according to the conditions set forth in the CFR's text and tables.
  • The “4A” category is still being used for the purposes of FIFRA Section 25(b), and USDA is still utilizing “List 4” for their National Organic Program.

For non-food inert ingredients, the 1987 List Category policy remains pertinent (including labeling) for those identified as "List 1" (toxicological concern).

For informational purposes you can still access EPA’s old inert list categories below. We no longer update these lists.

  • The following contains a listing of all the "inert" or "other ingredients" found in pesticide products registered by EPA. 

List 1: Inert Ingredients of Toxicological Concern

  • Classified on the basis of peer-reviewed studies which demonstrated carcinogenicity, adverse reproductive effects, neurotoxicity or other chronic effects, developmental toxicity (birth defects), ecological effects or the potential for bioaccumulation.
  • Original listing of List 1 inert ingredients contained over 50 chemical substances. Today approximately 10 of these substances are still used in pesticide products.

List 2: Potentially Toxic Other Ingredients/High Priority for Testing inerts

  • Many List 2 inert ingredients are structurally similar to chemicals known to be toxic; some have data suggesting a concern.

List 3: Inerts of unknown toxicity

  • An inert ingredient was placed on List 3 if there was no basis for listing it on any of the other lists. The Agency will continue to evaluate these chemical substances, as additional information becomes available, to determine if reclassification to List 1, 2, or 4 is appropriate.

List 4A: Minimal risk inert ingredients

  • The determination that a chemical is minimal risk would be based on a recognition of the overall safety of the chemical (such as very low toxicity or practically non-toxic) considering the widely available information on the chemical's known properties, and a history of safe use under reasonable circumstances.
  • Minimal risk (List 4A) substances are recognized as safe for use in all pesticide products subject only to good agricultural or good manufacturing practices since the Agency does not establish any restrictions on use patterns (how, where, when or in what manner the substance can be used) or limit the amount of a List 4A chemical substance that can be used as an inert ingredient in a pesticide product. It is noted that for a food-use application, the necessary tolerance exemption must be established. The substances on List 4A are the only inert ingredients that can be used in Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) section 25(b) deregulated or exempted products (see 40 CFRcl 152.25(f)(2)). Under FIFRA 25(b) the Agency does not review and evaluate the labeling for these products, and therefore cannot require the use of protective equipment.

List 4B: Other ingredients for which EPA has sufficient information to reasonably conclude that the current use pattern in pesticide products will not adversely affect public health or the environment.

  • In making a List 4B determination, the Agency evaluates not only the toxicity of the chemical substance, but also considers the particular exposures that could occur and the need for any restrictions.
  • The two critical distinctions between List 4A minimal risk substances and List 4B substances, are that while the Agency does not establish a use pattern or use limitation for a List 4A chemical substance, a List 4B may have such restrictions. Also, List 4 chemicals that are chemicals of higher acute toxicity are generally classified as List 4B, so that the Agency can evaluate the labeling and require the use of protective equipment.The substances on List 4B have no relevance to the provisions in FIFRA 25(b) for deregulated or exempted products.

The following lists are no longer updated. Refer to the InertFinder for currently approved inert ingredients.

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Last updated on March 14, 2024