Unneo Stales
Environmental Protection
Agency
Office of Wa:er
Office of Pestooes anc
Toxic SuDsts.-.ces
rc.. '.950
c/EPA National Pesticide Survey
Simazine
NHCH,CH,
Slmuln*
What is
Simazim
How Does
S/maz/ne
Beftave in
Soil and
Ground
Water?
The U.S. Environmental Protection Agency (EPA) has completed rts 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. Simazine was one of the pesticides
detected in the Survey. This fact sheet provides a description of simazine. its potential
hearth effects, and guidance on both treating and preventing well contamination.
Simazine is the common name of an herbicide which is a member of the
chemical ramify of triazines. Simazine was registered for use in the late 1960s. It has
been sold under the trade names of Aquazine, Princep, Gesatop, Weedex, Drexel
Simazine and the discontinued trade names of Framed and Simadex. Simazine is also
a component of otner herbicides such as Amizine, Pramitol 5PS, Simazol, Simazat,
and Remtal. Simazine is used to control broadleaf and grass weeds in com, citrus,
deciduous fruits and nuts, olives, pineapple, established alfalfa, and perennial grasses
grown for seed or pasture, turf grasses grown for sod, ornamentals, nursery plantings,
Christmas tree plantations, sugarcane, asparagus, and artichokes. It is also used as a
nonselective herbicide for vegetation control in non-agricultural land and for selective
control of algae and submerged weeds in ponds. It is approved for algae control in
swimming pools, large aquaria, ornamental fish ponds, fountains, and recirculating
water cooling towers.
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 teaching, 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
simazine 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. Simazine has a medium potential to be transported, and
a low potential to be transformed.
NPS Slmuin*
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How Does
S/maz/ne Get
into Ground
Water?
Findings of
the National
Pesticide
Survey
What Heart/)
Effects Might
be Caused by
S/maz/ne in
Drinking
Water?
How is Water
Treated to
Remove
Contami-
nants?
Simazine migration into ground water could result from the presence of sirr.azir.c
in the soil due to agricultural and other applications. Non-agricultural applications of
simazine include use on golf courses. Simazine could also reach ground water from
direct entry into a well through accidental chemical spills or improper storage near a
well.
Based on the results of the NPS, EPA estimates that simazine Is present, at or
above the analytical detection level of 0.38 yg/L used in the Survey, in about 1,080
(1.1%) CWS wells and 25,100 (0.2%) rural domestic wells nationwide. Considering the
precision of the Survey, EPA estimates that the number of CWS wells could be as low
as 350 or as high as 2,540, whereas the number of rural domestic wells could be as
low as 590 or as high as 141,000. Simazine is measured in micrograms per liter
(^g/L) which is equivalent to pans per billion (ppb). Simazine was not detected at
concentrations above EPA's drinking water Lifetime Health Advisory Level (HAL) and
proposed Maximum Contaminant Level (MCL) of 1 .0 ^g/L Other studies, however,
indicate concentrations above the HAL and MCL
Non-Cancer Effects: EPA has set a Lifetime Health Advisory Level tor simazine in
drinking water at 1 ^g/L. EPA believes that water containing simazine at or below this
level is acceptable for drinking every day over the course of one's lifetime, and does
not pose any health concerns. 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 simazine, however, at high levels well above
the Lifetime Health Advisory Level over a long period of time has been shown to result
in adverse hearth effects in animal studies, including tremors, damage to the testes,
kidneys, liver, and thyroid, disturbances in sperm production, and gene mutations.
Cancer Ri$k: EPA currently considers Simazine to be a possible human carcinogen
(cancer-causing agent). EPA estimates that if an individual consumes water
containing simazine at 0.3 ug/L over his or her entire lifetime, that person would
theoretically have no more than a one in a million chance of developing cancer as a
direct result of drinking water containing this pesticide
Standard: EPA sets enforceable standards for public water systems, called MCLs
These regulations set achievable levels of drinking water quality to protect human
health. The proposed MCL for simazine is 1 vg/L (Jury 25, 1990).
Simazine can be detected in drinking water by a laboratory using an EPA
method such as #507. If simazine is detected in well water and confirmed by
retesting to be above 1 pg/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. Public water
suppliers are required to notify customers if the drinking water that they deliver
contains a contaminant that exceed its MCL
You may also be able to treat your well water to remove pesticides and other
contaminants. Treatment technologies that can remove simazine from water include
granular and powder activated carbon adsorption. Other technologies such as ion
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.
NPS
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How Can
Water
Contamina-
tion be
Prevented?
Why was the
National
Pesticide
Survey
Conducted?
Where to Go
for More
Information
Several steps may be taken to prevent pesticides or nitrate from entering weiis,
such as eliminating direct entry through the well wall, drilling a new well, or modifying
or reducing pesticide and fertilizer use.
Eliminate Diract Entry Through tha 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 Will
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 Pastlclda 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 also find that you can 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 NPS 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).
Survty Datlgn
Survay Anatytat
Quality Assurance/
Quality Control
Analytical Met/tods
Summary Ratultt
Fact Sh*ef for aach
defected anaryta
Project Summary
Gloatary
How EPA Will Use
Tha NPS A*sufts
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
Information on regulation of
pesticides in drinking
water
NPS S/maz/n*
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National Pesticide Telecommunications Network
1-800-858-7378
24 hours a day
U.S. EPA Office of Pesticide Programs (OPP) Docket
Public Information Branch (H7506C)
401 M Street, SW
Washington, DC 20460
Telephone: (703) 557-2805
National Technical Information Service (NT1S)
528S Port Roy«i "oad
Springfield, VA 22161
(703) 487-4650
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. K 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 Hearth
Advisories. April, 1990.
U.S* Environmental Protection Agency. Hearth 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 S/mju/ne
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