s s


spacer s spacer

What's In a Pesticide?

We normally think of a pesticide as the product that can be purchased in the store – the insecticide, the weed killer or the fungicide. But, unfortunately, there is much more to it than that. The product that you buy or are exposed to is actually a pesticide formulation that contains a number of different materials, including active and inert ingredients, as well as contaminants and impurities. In addition, pesticides, when subject to various environmental conditions, break down to other materials known as metabolites, which are sometimes more toxic than the parent material. 

Active Ingredients

The active ingredient, usually the only component of the formulation listed on the pesticide label, is by nature biologically and chemically active against a target pest, be it an insect, weed or fungus. By definition these chemicals kill living things. 

Contaminants and Impurities

Contaminants and impurities are often a part of the pesticide product and responsible for product hazards. Dioxin and DDT have been identified as contaminants, which have not been purposefully added but are a function of the production process. 


Metabolites are breakdown products that form when a pesticide is used in the environment and mixes with air, water, soil or living organisms. Often the metabolite is more hazardous than the parent pesticide. 

Inert Ingredients

If you were to go to your local hardware store and take a look at the label on a can of ant and roach killer, the contents might read something like this, “5% Permethrin, 95% Inert Ingredients.” After reading the label, you may wonder what makes up the other 95%. The fact is, the manufacturer doesn’t have to tell you. Currently, under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), pesticide manufacturers are only required to list the active ingredients in a pesticide, leaving consumers and applicators unaware of the possible toxics present in the inert ingredients of pesticide products they are using, unless the EPA administrator determines that the chemical poses a public health threat. Pesticide manufacturers argue they cannot release information on inert ingredients because they are trade secrets, and if released, their products could be duplicated. Quite often inert ingredients constitute over 95% of the pesticide product. Inert ingredients are mixed into pesticides products as a carrier or sticking agent, and are often as toxic as the active ingredient. 

The Hazards of Inert Ingredients

Despite their name, these ingredients are neither chemically, biologically or toxicologically inert. In general, inert ingredients are minimally tested, however, many are known to state, federal and international agencies to be hazardous to human health. For example, the U.S. government lists creosols as a “Hazardous Waste” under Superfund regulations, yet allows these chemicals to be listed as inert ingredients in pesticide products. Creosols are known to produce skin and eye irritations, burns, inflammation, blindness, pneumonia, pancreatitis, central nervous system depression and kidney failure. Some inert ingredients are even more toxic than the active ingredients. One of the most hazardous ingredients in the commonly used herbicide RoundUp® is a surfactant, which is classified as an inert, and therefore not listed on the label. The pesticide naphthalene is an inert ingredient in some products and listed as an active ingredient in others. According a 2000 report produced by the New York State Attorney General, The Secret Ingredients in Pesticides: Reducing the Risk, 72 percent of pesticide products available to consumers contain over 95 percent inert ingredients; fewer than 10 percent of pesticide products list any inert ingredients on their labels; more than 200 chemicals used as inert ingredients are hazardous pollutants in federal environmental statutes governing air and water quality; and, of a 1995 list of inert ingredients, 394 chemicals were listed as active ingredients in other pesticide products.

What Can Be Done?

Beyond Pesticides/NCAMP is working to convince EPA to require that all pesticide ingredients, including inerts, are listed on all pesticide product labels. In the meantime, because of a successful 1996 lawsuit (NCAP and NCAMP v. Carol Browner, EPA) filed by the Northwest Coalition for Alternatives to Pesticides (NCAP) and Beyond Pesticides/NCAMP against EPA, people may systematically request the ingredients in specific pesticide product formulations through the Freedom of Information Act. To obtain this information, a request must be made in writing to the Public Information Officer of EPA, EPA Office of Pesticide Programs, Freedom of Information Office H7506C, 401 M Street, SW, Washington, DC 20460. If you are member of a non-profit organization or seeking information “in the public interest,” ask that your fees be waived “pursuant to 5 U.S.C. Section 522” and explain your tax status. Individual states also have similar laws, often called “Open Records Acts” which can be used. Visit the NCAP website for a sample request letter or reports on inert ingredients.

Regulatory Status of Pesticides

The standards of safety in the various statutes, whether the Food Quality Protection Act (FQPA) or the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), are based on risk assessments or risk benefit equations that bring with them a high degree of uncertainty as to the adverse impacts that pesticide exposure will have on various population groups. There is no disagreement that children, for example, exhibit higher vulnerability than adults to pesticide exposure and that risk assessments for most of the pesticides in use do not take this fact into account. The “unreasonable adverse effects” standard of safety in FIFRA allows EPA to accept risk levels among the population. The “reasonable certainty of no harm” standard in FQPA is defined as “negligible risk,” which provides for a risk assessment calculation that may adopt inaccurate assumptions about exposure patterns, background levels, previous exposures, and more. None of these calculations look at synergistic effects. There is very little attention to contaminants and impurities that are contained in pesticide products.

Existing pesticide use patterns and a deficient regulatory process add up to inadequate regulation of pesticides and is not protection of public health.  The vast majority of all pesticide products registered for use by EPA and state governments have never been fully tested for the full range of potential human health effects, such as cancer, birth defects, genetic damage, reproductive effects and neurological disorders, and endocrine disruption. Indeed, pesticides can be registered even when they have been shown to cause adverse health effects. Due to the numerous pesticide formulations on the market, the lack of disclosure requirements, insufficient data requirements, and inadequate testing, it is impossible to accurately estimate the hazards of pesticide products, much less lifetime exposure or risk. There is no way to predict the effects in children solely based on toxicity testing in adult or even adolescent laboratory animals, which is EPA’s procedure for evaluating adverse effects.