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From the Townsend Letter for Doctors & Patients
June 2004
Health Risks & Environmental Issues
by Rose Marie Williams, MA
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What Is Meant by "Inert" Ingredients?
When asked what the term "inert" means, most people respond with the commonly accepted dictionary meaning of the word, assuming "inert" refers to inactive, neutral, non- reactive, powerless, and so on. When consumers read pesticide product labels this is exactly what they believe "inert" ingredients to be — neutral and inactive, certainly nothing dangerous or toxic.
A wonderful booklet published by the Office of the New York State Attorney General, titled, "The Secret Hazards of Pesticides: Inert Ingredients," is quite an eye opener for the uninformed. It acknowledges, "many people will conclude the term 'inert' could not possibly have any adverse health or environmental effects. This is not the case at all. Chemicals used as inerts include some of the most dangerous substances known…suspected carcinogens…linked to long-term health problems like central nervous system disorders, liver and kidney damage and birth defects. They can also cause short-term health effects like eye and skin irritation, nausea, dizziness and respiratory difficulty."1

The United States Environmental Protection Agency (EPA) is responsible for regulating the use of pesticides and for protecting the public and environment from dangerous substances. EPA categorizes "inert" ingredients into four groups: substances known to cause long-term health damage and harm the environment, chemicals suspected of damaging health or the environment, chemicals of unknown toxicity, and those of minimal concern. EPA has published a list of chemicals used as "inerts," but does not indicate which products contain which chemicals. This is of no help to the consumer.1

Even the most conscientious consumer will learn very little from reading pesticide labels. Pesticide manufacturers are only required to list the "active" ingredient on product labels, the particular chemical intended to kill or inhibit some life form. All additional chemicals in the formulations are lumped together under "inert" ingredients. Pesticide is an umbrella term that includes insecticides designed to kill insects, herbicides designed to kill weeds, fungicides designed to kill molds, miticides against mites, and rodenticides to kill rodents.

The pesticide industry claims it has a right under confidentiality laws to prevent competitors from learning the ingredients in a product. However, modern laboratory technology using "reverse engineering" can easily discern the components of any product formulation. Consequently, it is the consumer who is left without adequate knowledge of product ingredients, and the health practitioner attempting to evaluate possible cause and effect of a patient's symptoms.

Dangerous "Inerts"
"Inert" as used on pesticide product labels is a serious misnomer that serves only to keep the public misinformed about potentially dangerous exposures to toxic substances. The following compounds represent a few examples of toxic chemicals used as "inert" ingredients in pesticide products.

Chloroethane is a suspected carcinogen which can cause eye irritation, abdominal cramps, nausea, vomiting, liver and kidney damage, nervous system dysfunction, and blood cell disorders.
Chloroform can cause irritation to eyes and gastrointestinal tract, nausea, dizziness, fatigue, and respiratory distress; liver and kidney damage; central nervous system depression; gonadal atrophy; fetal resorpton; coma and death by cardiac arrest. It is a mutagen and suspected carcinogen.
Cresols can cause skin irritation, burns and inflammation, eye irritation and blindness, pneumonia, pancreatitis, and central nervous system disorders.

can cause eye and throat irritation, photophobia, conjunctivitis, nausea and dizziness.

Dimethylphthalate can cause irritation of the eyes, mouth, and throat; dizziness, abdominal pain, nausea, vomiting and diarrhea; central nervous system depression; reduced respiratory rate; paralysis and coma.

Hexane is a neurotoxin, which can cause muscle wasting and atrophy.

Methyl Bromide can cause eye and skin irritation; blurred vision, headache, dizziness, nausea and abdominal cramps, anorexia; bronchopneumonia, pulmonary edema; brain damage, convulsions and coma; kidney and respiratory failure. Methyl bromide is also the "active" ingredient in pesticide products currently used in the cultivation of pumpkins, strawberries, tomatoes, and ornamental plants.

Toluene is associated with skin, eye and respiratory irritation; abdominal pain, headache, nausea, dizziness, drowsiness, hallucinations; anemia; liver disorders and enlargement; central nervous system dysfunction; coma and death.1-3

Many formulations used as "inert" ingredients are in fact, "hazardous substances," and are subject to the Superfund Amendments and Reauthorization Act (SARA). A number of toxic chemical products listed as the "active" ingredient in some pesticidal products are disguised as "inerts" in other products, depending on the manufacturer's designation of which pests are being targeted. Current registration allows hundreds of toxic chemicals to be listed as "inerts" on pesticide labels.2

At the present time EPA uses a limited set of criteria for evaluating and categorizing "inert" ingredients based on carcinogenicity, adverse reproductive effects, neurotoxicity, documented ecological effects, and potential for bioaccumulation. These criteria are limited and do not take into consideration endocrine disruption, allergic effects, and chemical sensitization, despite new information suggesting that "inert" ingredients can have these and other negative impacts on human health. Pets, wildlife and the environment also suffer from toxic exposure. The greatest impact falls upon agricultural workers and their families.2

State Petition Seeks to Disclose "Inerts"
In January 1998, the State Attorneys General of New York, Alaska, Connecticut, Massachusetts, Minnesota, New Hampshire, Wisconsin, and the Territory of Guam, later joined by Arizona and Illinois, filed a petition requesting EPA to require pesticide product labels to disclose the common chemical names of the "inert" ingredients contained in pesticide products. The State Petition notes that many chemicals listed as "inerts" are toxic, and are listed as the "active" ingredients in other pesticide formulations. These same "inerts" may be listed as "hazards" under other federal statutes. The State Petition further notes the failure to disclose "inert" ingredients poses "serious and ongoing risks to public health because it deprives the public of the ability to assess and address exposure to these toxic substances."4

Because of the health risks the State Petition requested expeditious action from the EPA. More than three years later, EPA had not rendered a decision on the matter prompting the states to compel EPA to act on the State Petition in which the states were seeking: a declaratory judgment declaring EPA had unreasonably delayed acting on the State Petition, and that such delay was unlawful; an injunction requiring EPA action within 60 days of the Court's determination that EPA's delay is unreasonable.

The State Petition acknowledged the United States Environmental Protection Agency as the agency responsible for the regulation of pesticides and the protection of public health from pesticide risk and exposure.4

The State Petition reiterated that pesticide formulations consist of one or more "active" ingredients, which are intended to kill or repel the target pest, and numerous other ingredients, which are known as "inert" or "other" ingredients. An "inert" is defined as an ingredient, which is not active. The Petition further notes that "inert" ingredients are not necessarily safe or inactive, and that even EPA acknowledges some "inert" ingredients are currently, or have been, listed as the "active" ingredient in many pesticide products.4

The current labeling regulation stipulates that only the "active" ingredient be identified by name on a product label. Only eight "inerts" out of approximately 2,300 "inert" ingredients are required to be listed on labels because EPA has determined them to be of "toxicological concern," despite the known and suspected toxicity that hundreds of additional "inerts" pose to public health. Therefore, in January 1998, the Attorneys General of nine states and the Territory of Guam jointly submitted a Petition to Require Disclosure of Inert Ingredients on Pesticide Product Labels. The Northwest Coalition for Alternatives to Pesticides (NCAP) and 180 other organizations filed a similar petition to require disclosure of "inert" ingredients on product labels. By June, an additional 80 organization signed onto the NCAP petition.4

A March 12, 1998, letter from EPA's Office of Pesticide Programs (OPP) to New York Assistant Attorney General, Andrew Gershon, acknowledged receipt of the State Petition indicating the Petition was "welcomed" as contributing to the (inert ingredient) dialogue, and that it would be "closely examined" by EPA. A November 1, 1999, follow-up letter to AAG, Gershon, stated that EPA was setting up a "working group" to advise EPA on ways of making information on "inert" ingredients more available to the public, but did not include a plan or timetable. For three years EPA did nothing to resolve the "inert" ingredient issue. The plaintiffs considered EPA's delaying action and failure to respond to the State Petition "unlawful."4

Carolyn Cox, staff scientist for the Northwest Coalition Against Pesticides (NCAP), has been a major force representing the many environmental and health organizations demanding disclosure of all ingredients on pesticide product labels. Ms. Cox was even appointed to EPA's "working group," to represent the many health and environmental organizations demanding full disclosure of all "inert" ingredients. EPA wanted the "working group" to arrive at a consensus, but industry representatives refused to budge as did those representing public health concerns. The result is that EPA decided on voluntary disclosure as per industry's request.5

Percent "Inerts" in Sample Products
A quick look at some pesticide products illustrates the high percentage of "inert" ingredients in the formulations.

It bears mentioning that the chemical companies that manufacture pesticides are intimately involved with the petrochemical/agrichemical/pharmaceutical industries. Increased numbers of grassroots health advocates are becoming wary of the fact that many pharmaceutical companies that produce drugs to treat cancer also manufacture toxic pesticides suspected of promoting cancer.

Consumer Action
Advice from Carolyn Cox to consumers is to avoid toxic pesticide products whenever possible, and if your workplace or municipality uses such products, bring up the issue of "inert" ingredients as potentially harmful chemicals. Ask that someone contact the pesticide manufacturer requesting to know what the "inert" ingredients are. She said, "Pesticide companies need to hear from their customers." The NCAP web site ( contains a sample letter for inquiring about "inert" ingredients. Ms. Cox indicated she would be happy to discuss the issue with anyone who wished to inquire further. She can be reached at 541-344-5044, or

Residents of states not yet included in the "State Petition" requesting that EPA require pesticide manufacturers to disclose all ingredients on product labels may wish to encourage their attorneys general to sign onto this important document in support of public health. The more states that sign onto the petition should bolster EPA's ability to act on behalf of public health instead of giving in to corporate demands. The public and the medical profession have a right to know this information.

1. "The Secret Hazards of Pesticides: Inert Ingredients," Office of the Attorney General of New York State, Environmental Protection Bureau, Albany, NY (518-474-5481), January 1999.
2. States of NY, CT, AK, & MA (Plaintiffs) v. US EPA (Defendants), "Complaint for Declaratory and Injunction Relief" Civ. No. 1:01CV00379 (PLF), Exhibit A, January 1998.
3. National Pesticide Telecommunications Network (NPTN), 800-858-7378.
4. States of NY, CT, AK, & MA (Plaintiffs) v. US EPA (Defendants), "Complaint for Declaratory and Injunction Relief" Civ. No. 1:01CV00379 (PLF), January 1998.
5. Cox, Carolyn, Northwest Coalition Against Pesticides (NCAP), Eugene, OR, (541-344-5044).




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