What Is An Inert Ingredient?
Northwest Coalition for Alternatives to Pesticides
Also: Important NCAP Information and Links Below
Our national pesticide law classifies pesticide ingredients into
two categories, "active" 1 and "inert." 2
Active ingredients are those that are designed to kill. Legally,
they are defined as chemicals that "destroy, prevent, repel,
or mitigate" 1 any pest.
Inerts are all other ingredients used in pesticide products 2
and are added to active ingredients to make the pesticide
more potent or easier to use.
Solvents, surfactants, and carriers are examples of the kinds
of ingredients commonly used as inerts. 3
Inert ingredients are not inert in the usual sense of the word;
they are neither chemically, biologically, nor toxicologically inert. 4
Does the public know the inert ingredients in most pesticide products?
Pesticide manufacturers claim that the identity of many inert
ingredients is confidential business information and will not publicly
Under the Freedom of Information Act, the public can request
information from the U.S. Environmental Protection Agency (EPA)
about the inerts in a pesticide product and it will be provided unless
the manufacturer makes a confidentiality claim. 5
Are "inert" ingredients regulated differently than active ingredients?
In brief, the answer to this question is yes.
Under amendments to our national pesticide law passed in 1972,
active ingredients are required to be tested for a battery of
toxicological and ecological problems. 6
Since 1972, EPA has been attempting to bring testing for each
registered active ingredient up to these standards. 6
Inert ingredients, on the other hand, were not subject to testing
requirements until 1987. 7
The requirements for health and safety testing of inerts which EPA
established at that time were called "minimal" 7 even by EPA.
They did not include tests for the following serious hazards: 7
* the ability to cause cancer
* the ability to adversely affect fertility and reproduction
* the ability to damage the nervous system
No tests at all were required of inerts already in use in 1987;
testing requirements apply only to inerts first used in pesticides
since that date. 7
In addition, EPA requires very little testing for the potential hazards
of the combination of active and inert ingredients, 8 even though
humans and the environment are actually exposed to this chemical
cocktail when a pesticide is used.
Does the combination cause cancer?
Does the combination cause birth defects or other reproductive
Does the combination cause adverse effects following long-term
None of these questions can be answered based on current testing
How much information does EPA have about the hazards of inert
The lack of testing requirements means that EPA has very little
information about the hazards posed by "inerts."
Of the over 2300 substances EPA has identified as "inerts" in
pesticide products, 9 EPA classifies most (over 1700) as "unknown
toxicity" 9 because EPA's Office of Pesticide Programs does
not have adequate information about their hazards.
However, there is clear evidence that many inerts pose significant
toxicological and environmental hazards.
State, federal, and international agencies have classified 26 percent
of them (610 chemicals) as hazardous. 10 Specific inert ingredients
have well-known hazards, including:
* Crystalline silica is classified as a carcinogen by the International
Agency for Research on Cancer. 11
* Nonyl phenol ethoxylates cause destruction and deterioration
of fish gills. 12
* Ethylbenzene causes fetal loss, birth defects, and testicular
* Xylenes cause vomiting, mild liver toxicity, impaired short-term
memory, and reduced fertility. 14
* Trimethylbenzenes cause bronchitis, fatigue, and dizziness. 15
* Cumene causes narcotic effects and depression of the central nervous
* Chlorofluorocarbons cause destruction of stratospheric ozone. 17
[See the Solvent Information Page]
Why is public disclosure of the identity of inert ingredients important?
It is impossible for pesticide users, whether they are government
agencies, businesses, or homeowners, to accurately understand the
hazards of a pesticide product they are proposing to use if they don't
know its ingredients.
Our national pesticide law, the Federal Insecticide, Fungicide and
Rodenticide Act, requires EPA to regulate to prevent "unreasonable
adverse effects on the environment."
EPA can't do this accurately if the ingredients of pesticide in question
and their hazards are unknown.
"Inert" ingredients are a crucial ethical issue. We are all exposed
to pesticides on a daily basis, whether or not we like that exposure.
Given this situation, the very least we can do is to insure that we
have complete, easily and publicly accessible infomation about
all of the ingredients in pesticide products.
Also: Important NCAP Information and Links Below
1. Federal Insecticide, Fungicide and Rodenticide Act (FIFRA)
2. FIFRA Sec. 2(m)
3. U.S. EPA. Office of Public Affairs. 1987. Environmental news.
D.C., Apr. 21.
4. "" Office of Pesticide Programs. 1997. Pesticide regulation
notice 97-6, D.C. http://www.epa.gov/oppmsd1/pr97-6.html.
5. Northwest Coalition for Alternatives to Pesticides, Browner 941
F. Supp. 197.
6. U.S. General Accounting Office. 1993. Pesticide reregistration
may not be completed until 2006. Washington, D.C., May.
7. U.S. EPA. 1987. Inert ingredients in pesticide products; Policy
statement. Fed. Reg. 52(77):13305-13309, Apr. 22.
8. Code of Federal Regulations 40 § 158.340.
9. U.S. EPA. 1998. List inert ingredients
10. S. Marquardt, C. Cox, and H. Knight. 1998. Toxic secrets:
"Inert" ingredients in pesticides: 1987-1997. Northwest Coalition for
Alternatives to Pesticides.
11. International Agency for Research on Cancer. 1999. Overall
evaluations of carcinogenicity to humans.
12. Pärt, P., O. Svanberg, and E. Bergström. 1985. The influence of
surfactants on gill physiology and cadmium uptake in perfused
rainbow trout gills. Ecotoxicol. Environ. Safety 9:135-144.
13. U.S. Dept. of Health and Human Services. Public Health Service.
Agency for Toxic Substances and Disease Registry. 1997. Atlanta,
14. U.S. Dept. of Health and Human Services. Public Health Service.
Agency for Toxic Substances Disease Registry. 1997 for total
xylenes. Atlanta, GA, Aug.
15. Sittig, M. 1991. Handbook of toxic and hazardous chemicals and
carcinogens. 3d edition. Vol. 2. Park Ridge, NJ: Noyes Publications.
16. Sigma Chemical Co., Aldrich Chemical Co., and Fluka Chemical
Co. 1994. Material Safety Data Sheet: Cumene. St. Louis,
Milwaukee, Ronkonkoma, NY.
17. U.S.EPA. 1995. Ozone-depleting Chemicals
Northwest Coalition for Alternatives to Pesticides (NCAP)
PO Box 1393
Eugene, OR 97440
Phone (541) 344-5044;
Fax (541) 344-6923
(Provides excellent publications and much information on pesticide use in schools).
Coalition for Alternatives to Pesticides