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Vol. 12 Issue 2, Spring 2007

Inert Ingredients in Pesticide Products
The Ribbon 

By Laschelle Dana-Marie Stewart, BCERF Research Assistant, and Suzanne Snedeker, Ph.D., BCERF Associate Director for Translational Research

Pesticide products contain chemicals that control the pest (called active ingredients) and other added ingredients called inert ingredients. While inert ingredients don’t control the pest, they can make up the bulk of the product on a weight basis, and they may be chemically or biologically active. While some pose no risk (e.g. water), other substances used as inert ingredients may pose hazards to people and the environment. The following article includes a summary of basic information on inerts, issues of concern expressed by consumer groups and state agencies, and actions taken by federal and state agencies to address some of the current issues.

What is an inert?
An inert ingredient is any substance, other than the pesticide active ingredient, that is intentionally included in a pesticide product (EPA, 2006a) For instance, inert ingredients may include substances that are solvents, extend the product’s shelf life, or protect a product’s degradation from sunlight (EPA, 2006a). Many inerts are used to dissolve or deliver the pesticide active ingredient. Inert ingredients can make up the bulk of the product on a weight basis (AGO et al., 2006).

The Environmental Protection Agency (EPA) defines inert ingredient as “an ingredient that has no pesticide activity but can be biologically active (e.g., water, solvents, emulsifiers, surfactants, clay or propellants” (EPA, 2007b).

What’s on the pesticide label?
Under current labeling regulations, the name of the pesticide active ingredient and its percent by weight must be stated on the pesticide product label. There are different rules for inert ingredients. There is no requirement that the inert ingredients be identified by name, or that the toxicity of inert ingredients be stated on the pesticide product label. Only the total percentage of the inert ingredients is required to be on the pesticide product label (EPA, 2007a). Some manufacturers voluntarily name inert ingredients on pesticide labels, or they may give general descriptions of a type of chemical used as inert (e.g. “product contains petroleum distillates”). A report issued by the New York State (NYS) Attorney General’s office in 2000 estimated that while most pesticide products contain inert ingredients, only 10% of the products commonly used in NYS listed any of the actual inert ingredients (Surgan et al., 2000).

Does “inert” mean inactive or non-toxic?
While inert ingredients used in pesticide products don’t control or kill the pest, this does not mean that all inert ingredients are chemically or biologically inactive, or non-toxic (EPA, 2007a, b). While some may be innocuous (like water), other inert ingredients can pose a risk to people, pets, beneficial insects or the environment. In a report released in 1999, it was estimated that about 26% of the inert ingredients used in pesticide products had some toxic properties (Cox, 1999). Environmentalists and state agencies have noted that many inert ingredients used in pesticide products are listed as hazardous chemicals under the Clean Air Act, the Clean Water Act, and the Safe Drinking Water Act (AGO et al., 2006; Cox, 1999).

Does EPA have a system to rank the toxicity of inerts?
In response to concerns expressed about the toxicity of inerts, in 1987 the EPA announced the development of an “Inerts Strategy” that called for the “use of the least toxic ingredients available” (EPA, 2006b, 2007b). As a part of this effort, the EPA developed a four-tier system based on the known toxicity of the inerts and also ranked inerts that needed further toxicological testing. The four lists developed by EPA include: List 1, Inerts of Toxicological Concern; List 2, Potentially Toxic Inerts with a High Priority for Testing; List 3, Inerts of Unkown Toxicity; List 4A, ‘Minimal Risk Inerts; and List 4B, Inerts that will not adversely affect public health or the environment given current use patterns (AGO et al., 2006; EPA, 2007b).

EPA’s Office of Pesticides and Pollutants (OPP) is responsible for assessing the toxicological and ecological impacts of inert ingredients. Over the last 20 years, the EPA has extensively revised the lists based on the availability of additional toxicity data. Some of the inert ingredients on the 1987 lists are no longer used in pesticide products. Others were moved from List 3 (unknown toxicity) to List 4B. List 4A (minimal risks) was recently revised in August of 2004. However, many of the chemicals in List 4A may pose risks to certain vulnerable groups, especially those with allergies. For instance, allergens including egg, tree and ground nuts, and corn products are included in list 4A (EPA, 2004a).

Are “inert ingredients” and “other ingredients” the same thing?
The EPA issued an official notice in 1997, which encouraged manufacturers and registrants of pesticide products to use the term “other ingredients” as a replacement term for inert ingredients on pesticide product labels. The EPA found that the term “inert ingredients” could mislead consumers. A survey found that consumers thought the term “inert” meant harmless or non-toxic. Therefore, the term “other ingredients” has been recommended as a more appropriate term for the ingredients that are not listed as “active ingredients” on pesticide product labels (EPA, 2007a).

Why is there concern about inert ingredients?
Environmental organizations, consumers, and policy makers at the state and federal levels have expressed concern about human and environmental health effects of many substances used as inert ingredients as well as the current limited access to information on inerts on the pesticide label. On the other hand, manufacturers have also expressed concern about listing all inert ingredients in a product on the label since this affects confidentiality about the composition of the pesticide product. To what extent inert ingredients should be considered trade secrets or confidential business information has been hotly debated. These areas of concern are summarized below.

Health hazards. Some inert ingredients may pose a potential health hazard to people, pets, wildlife and ecosystems. Some inert ingredients can increase the toxicological risk of certain pesticide products to humans and animals, such as the disruption of hormone functions or the development of the nervous system, while others may act as carcinogens or allergens. Other inerts may have acute effects, including eye irritation, difficulty breathing, nausea, and dizziness (AGO et al., 2006). Access to information on inert ingredients in pesticide products is also needed by physicians, poison control professionals, and other emergency responders. Those who work with pesticides (e.g. farmers and pest control professionals) need to be able to identify inert ingredients in the pesticides they use to take action to protect themselves and consumers who may be exposed to the pesticide product ingredients (AGO et al., 2006; EPA, 2004b). Concern has also been expressed about the effect some inert ingredients may have on non-targeted plants, animals, fish, birds, insects, amphibians, and microorganisms in ecosytems (AGO et al., 2006; Cox and Surgan, 2006; EPA, 2004b). Concern has been expressed that that far fewer toxicity tests are required for inerts compared to pesticide active ingredients (Surgan, 2005).

Informed choice. Consumers have a right to make informed decisions about their purchases. Current labeling law does not provide information on name or toxicity of inert ingredients (AGO et al., 2006). As mentioned previously, the EPA found that many consumers do not understand the term inert ingredient, and perceive inerts are harmless. Consumers who want to avoid certain ingredients cannot make an informed choice since they do not have access to full ingredient information on a pesticide label.

Misleading information. The Attorney General’s Office of NYS has stated that pesticide manufacturers and pest control services were using the lack of knowledge surrounding inerts to their advantage when advertising claims about the health and environmental impacts of pesticides. The AGO cited instances when the health effects of only the active ingredients and not the inert ingredients were mentioned in advertisements (Surgan, 2005; Surgan et al., 2000).

Business confidentiality. Pesticide manufacturers that hold the registration (registrants) for a particular pesticide product have expressed concern about listing all inert ingredients on the label. Currently, some inert ingredient information is protected as confidential business information (Cox and Surgan, 2006). Manufacturers feel that disclosing the name of the inert ingredients in the pesticide product could give their competitors an advantage, since many inerts improve ease in application, effectiveness, and stability of the product. Manufacturers feel that full disclosure of the pesticide product ingredients would allow competitors to copy and reproduce pesticide formulations, especially when patent law protections don’t apply to a particular product (EPA, 2004b). Opponents counter that the there is a need for public disclosure, since currently there are significant delays (e.g. prolonged litigation or lengthy FOIA requests) when consumers or others seek to identify the specific chemicals used as inert ingredients in pesticide products (Cox and Surgan, 2006).

What is being done to address these concerns?
Action by State Attorneys General. Attorneys General from 13 states (including NYS) and the US Virgin Islands sent a petition to the EPA in August 2006 requesting that the EPA amend the rules which govern the disclosure of inert ingredients on pesticide product labels. The petition specifically asked that the administrator of the EPA require pesticide manufacturers and formulators to disclose on the pesticide label any inert ingredients for which “determinations of hazard have been made by the EPA” (AGO et al., 2006). Resource information on inerts and current areas of concern are available from the NYS Attorney General’s Office. This includes statements and articles on issues concerning the health risks posed by inert ingredients in pesticide products (go to: and put “inert” in search box) (Surgan et al., 2000).

EPA-sponsored dialogues on improving disclosure. In 1995, the EPA established the Pesticide Program Dialogue Committee (PPDC) to create a forum where diverse stakeholder groups could discuss issues, and provide feedback to the EPA on current pesticide regulations and implementation of pesticide policy. The PPDC is composed of members from the pesticide industry, user and commodity groups, federal and state governments, the general public, academia, and public health organizations (EPA, 2007b). A working group was formed and met specifically to address concerns about inert disclosure starting in January 1999 and continuing through April 2002 (though additional reports were submitted up to the April 16-17, 2003 PPDC meeting). Issues discussed by the Inert Disclosure Stakeholder Working Group included:

The final report of the activities and discussion papers written by the Inert Disclosure Stakeholder Working Group are available on the EPA website at:

It is likely that issues concerning disclosure of inert ingredients and more rigorous evaluation of health hazards of inerts will continue to be debated. The challenge is how to provide information to those who need it (interested consumers, consumers with chemical sensitivities, health professionals and emergency responders, professional pesticide applicators and safety educators), versus how much information should be displayed on the label. There are already documented problems of consumers not reading or understanding label directions nor fully understanding acute and long-term health effects of exposures to pesticide products. Clearly a different approach may be needed, including databases with accessible risk information on both active and inert ingredients, and labels that more clearly portray health risks and precautions that need to be taken.


AGO, State, N.Y., Alaska, Arizona, California, Connecticut, Illinois, Maine, Maryland, Massachusetts, Jersey, N., Mexico, N., Oklahoma, Island, R., Islands, U.S.V., and Wisconsin (2006). Petition of New York, Alaska, Arizona, California, Connecticut, Illinois, Maine, Maryland, Massachusetts, New Jersey, New Mexico, Oklahoma, Rhode Island, The United States Virgin Islands and Wisconsin requesting that the United States Environmental Protection Agency amend its rules governing the disclosure of "inert" ingredients on pesticide labels to require the disclosure of ingredients for which federal determinations of hazard have already been made, August 1, 2006 (pdf of petition available at < >, cited 5/16/07), pp. 1-43.

Cox, C. (1999). Inert ingredients in pesticides: who's keeping secrets. Journal of Pesticide Reform 19, 1-7.

Cox, C., and Surgan, M. (2006). Unidentified inert ingredients in pesticides: implications for human and environmental health. Environmental Health Perspectives 114, 1803-1806.

EPA (2004a). Complete list of other (inert) ingredients in pesticide products 07-30-2004, (, cited 05/09/07) (Environmental Protection Agency), pp. 1-135.

EPA (2004b). Final report to the pesticide program dialogue committee on the activities of the inert disclosure stakeholder workgroup, March 2000-April 2002, (, cited 5/9/07) (Environmental Protection Agency), pp. 1-62.

EPA (2006a). Inert (other) pesticide ingredients in pesticide products - categorized list of inert (other) pesticide ingredients, updated August 2004 (, cited 5/9/07) (Environmental Protection Agency), pp. 1-3.

EPA (2006b). Pesticides: regulating pesticides; inert ingredients in pesticide products; policy statement, (, cited 2/28/07) (Environmental Protection Agency), pp. 1-14.

EPA (2007a). Inert (other) ingredients in pesticide products, (, cited 5/16/07) (Environmental Protection Agency), pp. 1.

EPA (2007b). Information for pesticide manufacturers (, cited 4/13/07) (Environmental Protection Agency), pp. 1-4.

Surgan, M. (2005). Toxicity tests: "inert" and active ingredients (letter). Environmental Health Perspectives 113, A657-A658.

Surgan, M.H., Gershon, A.J., Lehner, P., and Spitzer, E. (2000). The secret ingredients in pesticides: reducing the risk, ( (New York, NY, Office of the Attorney General, Environmental Protection Bureau), pp. 1-35.

About the Co-Author: Laschelle Dana-Marie Stewart, an undergraduate in the College of Arts and Sciences, worked for Dr. Suzanne Snedeker as a research assistant during this past spring semester. Her responsibilities included researching and co-authoring this article. Laschelle is completing her junior year as a Feminist Gender and Sexuality Studies major, with an Africana concentration. She is interested in pursuing a career in policy and public health research, though her first goal is to complete a law degree. Laschelle has been a wonderful addition to the BCERF team, and she has enjoyed the experience gained in working on this translational research project. "The best thing about working for BCERF is the wealth of knowledge I've gained about research approaches and sources of information." Laschelle has served as President of the Black Woman's Support Network at Cornell, and serves as Secretary for Alpha Kappa Alpha Sorority, Mu Upsilon Chapter, and as a peer advisor for the College of Arts and Sciences.

Web Links of Interest

US Environmental Protection Agency (EPA)

Definitions and basic information on inert (other) ingredients

EPA policy statement on reducing the potential for adverse effects from using pesticides containing toxic inert ingredients (1987)

Information on the EPA’s inert strategy

Categorized list of the toxicity of inert (other) pesticide ingredients (revised August 2006)

Final report to the Pesticide Program Dialogue Committee on the activities of the Inert Disclosure Stakeholder Workgroup (April 2002)

Office of the New York State Attorney General (put ‘inert’ in search box to obtain list of documents)

The Secret Ingredients in Pesticides

Greenmarketing in the yellow pages: deceptive advertising of pest control services

Press release issued on August 1, 2006 on the petition presented by state agencies to the EPA requesting disclosure of hazardous inert ingredients

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