United States
Environmental Protection
Agency
Office of Water
Office of Pesticides and
Toxic Substances
Fall 1990
«>EPA National Pesticide Survey
Atrazine
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NHCH2CH3
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:N
NHCH(CH3)2
Atrazine
What is
Atrazine?
How Does
Atrazine
Behave in
Soil and
Ground
Water?
How Does
Atrazine Get
into Ground
Water?
The U.S. Environmental Protection Agency (EPA) has completed its five-year
National Survey of Pesticides in Drinking Water Wells (NPS), a study of the presence
of 127 pesticides, pesticide degradates, and nitrate in community water system (CWS)
wells and rural domestic drinking water wells. Atrazine was one of the pesticides
detected in the Survey. This fact sheet provides a description of atrazine, its potential
health effects, a summary of the concentrations of atrazine found by the NPS in wells,
and guidance on both treating and preventing well contamination.
Atrazine is the common name of an herbicide which is a member of the
chemical family of triazines. Atrazine was registered for use in the late 1950s. It has
been sold under the trade names of Atrazine, AAtrex, Atratol, Gesaprim, and Zeaphos.
Atrazine is also a component of other herbicides such as Bicep, Bullet, Extrazine,
Lariat, Marksman, Prozine, and Sutazine. Atrazine is used to control many annual
broadleaf weeds and certain grasses in corn, sorghum, sugarcane, macadamias, and
subtropical tree fruits such as guavas and pineapples. It is also used for general
weed control on non-cropped industrial land, selective weed control in conifer
restoration and Christmas tree plantations, and non-selective control of vegetation on
fallow land.
The behavior of a pesticide after it is released to the environment is dependent
upon its movement in air, water, and soil as well as the rate at which it is transformed
or broken down. Pesticides applied to crops or the soil surface may volatilize
(vaporize) to the atmosphere, be carried off by surface runoff, be carried to ground
water through leaching, or remain in the soil through adsorption (adherence) to soil
particles and undergo little movement in air or water. Pesticides may be transformed
by reaction with water, microorganisms, and exposure to sunlight. The likelihood that
atrazine will migrate into ground water is influenced by its tendency to be transported
(move) from soil to air and water and to be transformed by these various processes,
as well as by the characteristics of the site, such as soil type, moisture, temperature,
and depth to ground water. Atrazine has a high potential to be transported, and a low
potential to be transformed.
Atrazine migration into ground water could result from the presence of atrazine
in the soil due to agricultural and other applications of atrazine on cropped and non-
cropped land. Atrazine could also reach ground water from direct entry into a well
through accidental chemical spills or improper storage near a well.
NPS Atrazine
Printed on Recycled Paper
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Findings of
the National
Pesticide
Survey
What Health
Effects Might
be Caused by
Atrazine in
Drinking
Water?
How is Water
Treated to
Remove
Contami-
nants?
Based on the results of the NFS, EPA estimates that atrazine is present, at or
above the analytical detection level of 0.12 /L/g/L used in the Survey, in about 1,570
(1.7%) CWS wells and 70,800 (0.7%) rural domestic wells nationwide. Considering the
precision of the Survey, EPA estimates that the number of CWS wells with detectable
levels of atrazine could be as low as 420 or as high as 2,710, and the number of rural
domestic wells could be as low as 13,300 or as high as 214,000. Atrazine is
measured in micrograms per liter (/ug/L) which is equivalent to parts per billion (ppb).
The maximum concentration of atrazine detected was 0.92 pg/L in CWS wells sampled
by the Survey and 7.0 pg/L in rural domestic wells sampled by the Survey. The
median concentration of detectable atrazine was 0.26 pg/L in CWS wells, and 0.29
/ug/L in rural domestic wells.
Atrazine was sometimes detected at concentrations above EPA's proposed
Maximum Contaminant Level (MCL) and drinking water Lifetime Health Advisory Level
(HAL) of 3 pg/L in rural domestic wells. Other studies have also indicated atrazine
concentrations above the HAL. EPA notified well owners and operators within 24
hours when detections were above the Health Advisory Level.
Non-Cancer Effects: EPA has set a Lifetime Health Advisory Level for atrazine in
drinking water at 3 /^g/L EPA believes that water containing atrazine at or below this
level is acceptable for drinking every day over the course of one's lifetime, and does
not pose health concerns. A Lifetime HAL represents the concentration of a
contaminant in water that may be consumed over an average human lifetime without
causing adverse health effects. Lifetime HALs are based on health effects that were
found in animals given high doses of the pesticides in laboratory studies. This level
includes a margin of safety. Consuming atrazine, however, at high levels well above
the Lifetime Health Advisory Level over a long period of time has been shown to result
in adverse health effects in animal studies, including tremors, changes in organ
weights, and damage to the liver and heart.
Cancer Risk: EPA has not officially classified the carcinogenicity (cancer-causing)
potential of atrazine. There is limited or uncertain information indicating that atrazine
causes cancer in animals receiving high doses of the chemical over the course of their
lifetimes. Because atrazine in drinking water may possibly increase the risk of cancer
in humans, the Lifetime Health Advisory Level includes an additional margin of safety.
Standard: EPA sets enforceable standards for public water systems, called MCLs.
These regulatory standards set achievable levels of drinking water quality to protect
human health. The proposed MCL for atrazine is 3 ^g/L (proposed as of May 22,
1989). .
Atrazine can be detected in drinking water by a laboratory using an EPA
method such as #507. If atrazine is detected in well water and confirmed by retesting
to be above 3 ng/L, State or County health officials should be consulted. They may
advise periodic retesting to get an accurate overall picture of the water quality
because changes in seasonal precipitation and changes in pesticide use can cause
variations in the amount of chemicals found in water wells. They also may advise
using an alternative drinking water supply (bottled water is an example of a temporary
alternative), treating the water, or drilling a new or deeper well. If you receive your well
water from a community water system, and have concerns about the quality of your
water, contact your State public water supply agency. Public water suppliers are
required to notify customers if the drinking water that they deliver contains a
contaminant that exceeds its MCL.
You may also be able to treat your well water to remove pesticides and other
contaminants. Treatment technologies that can remove atrazine from water include
granular and powder activated carbon adsorption. Other technologies such as ion
NFS Atrazine
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How Can
Water
Contamina-
tion be
Prevented?
Why was the
National
Pesticide
Survey
Conducted?
Where to Go
for More
Information
exchange, reverse osmosis, ozone oxidation, and ultraviolet irradiation are in the
experimental stages for this pesticide and are not necessarily appropriate or available
in every situation. Certain treatment methods are more suitable for large community
water systems than for individual domestic wells. State or County health officials
should be able to provide advice on the best approach to follow.
Several steps may be taken to prevent pesticides or nitrate from entering wells,
such as eliminating direct entry through the well wall, drilling a new well, or modifying
or reducing pesticide and fertilizer use.
Eliminate Direct Entry Through the Well Wall
If pesticides or nitrate are present in well water, they may be entering the
ground water through the well itself rather than through the soil. If the well is old or
poorly constructed or if there are visible cracks in the well casing, obtain expert advice
on whether or not improvements can be made to the well. In addition, investigate
simple methods of capping the well or sealing it at the surface to prevent entry. Do
not conduct any mixing activities near the well if you use well water to mix pesticides
because a spill could lead to direct contamination of the well.
Drill a New Well
If the soil surrounding the well is the source of contamination, drilling a new or
deeper well may make sense if water can be drawn from a deeper, uncontaminated
aquifer. Unfortunately, it often is difficult to know the quality of the ground water
without drilling or extensive testing. Seek expert advice before you drill.
Learn More about Pesticide Use
If you use pesticides, whether for agricultural or home lawn and garden
purposes, you should consider attending training courses given by your State or
County agriculture department on how to reduce activities that can contaminate
ground water. You may find that you can eliminate or lessen the frequency or quantity
of your pesticide usage by choosing alternative methods of pest control.
EPA conducted this Survey to determine the frequency and concentration of
pesticides, pesticide degradates, and nitrate in drinking water wells nationwide and to
examine the relationship between the presence of pesticides in drinking water wells
and patterns of pesticide use and ground-water vulnerability. The Survey sampled
566 community water system wells and 783 rural domestic wells for 127 pesticides,
pesticide degradates, and nitrate. The wells were selected as a representative
statistical sample to provide nationwide estimates of the presence of pesticides and
nitrate in drinking water wells, and are not meant to provide an assessment of
pesticide contamination at the local, County, or State level.
This fact sheet is part of a series of NFS outreach materials, fact sheets and
reports. The following additional fact sheets are available through EPA's Public
Information Center (401 M Street SW, Washington, DC 20460, (202) 382-2080):
Survey Design
Survey Analytes
Quality Assurance/
Quality Control
Analytical Methods
Summary Results
Fact Sheet for each
detected analyte
Project Summary
Glossary
How EPA Will Use
The NPS Results
WPS Atrazine
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Additional information on the Survey and on pesticides in general can be
obtained from the following sources:
U.S. EPA Safe Drinking Water Hotline
1-800-426-4791 (In Washington, DC (202) 382-5533)
Monday-Friday, 8:30 am to 4:30 pm Eastern Time
National Pesticide Telecommunications Network
1-800-858-7378
24 hours a day
U.S. EPA Office of Pesticide Programs (OPP) Docket
401 M Street, SW Room NEG004
Washington, DC 20460
(202) 382-3587
National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
Information on regulation of
pesticides in drinking
water
Information on health
effects and safe
handling of pesticides
Background documents
for Survey (available
for review)
Copies of the
NPS Phase I Report
(available 1991)
and
NPS Phase II Report
(when available)
If you are concerned about the presence of pesticides and nitrate in your
private water well, contact your local or State health department. Other experts in
your State environmental agency or agriculture and health departments may also be
helpful to you. If you receive your drinking water from a community water system and
have questions about your water quality, contact your local community water system
owner/operator or the State water supply agency.
Bibliography Meister Publications. Farm Chemicals Handbook. Ohio: Meister Publications, 1990.
U.S. Environmental Protection Agency. Drinking Water Health Advisory: Pesticides.
Michigan: Lewis Publishers, 1989.
U.S. Environmental Protection Agency. Drinking Water Regulations and Health
Advisories, April, 1990.
U.S. Environmental Protection Agency. Health Advisory Summaries. January 1989.
U.S. Environmental Protection Agency. Pesticides in Drinking Water Wells, September
1989.
Weed Science Society of America. Herbicide Handbook of the Weed Science Society
of America. 5th ed. Illinois: Weed Science Society of America, 1983.
Worthing, Charles R., ed. The Pesticide Manual. 8th ed. Thornton Heath: The British
Crop Protection Council, 1987.
NPS Atrazine
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