v>EPA
United States
Environmental Protection
Agency
Office of Water
Office of Pesticides and
Toxic Substances
Fall 1990
National Pesticide Survey
Ethylene Thiourea
CH- - NH
CH2 — Nh
V
>=s
Ethylene Thiourea
(ETU)
What is ETU?
How Does
ETU Behave
in Soil and
Ground
Water?
How Does
ETU 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. Ethylene thiourea (ETU), a breakdown
product of ethylene bisdithiocarbamate (EBDC) fungicides, was detected by the
Survey. This fact sheet provides a description of ETU, its potential health effects, and
guidance on both treating and preventing well contamination.
Ethylene thiourea is a degradation product of fungicides from the chemical
family of EBDCs. Common names of fungicides that produce ETU include Mancozeb,
Maneb, Metiram, and Zmeb. EBDCs were used in 1935 and registered in the late
1940s. EBDC pesticides are used to control fungus on roses and other flowers and a
broad range of crops including potatoes, tomatoes, lettuce, apples, pears, and hops.
EPA has proposed cancellation of many uses of EBDC pesticides within the next
several years. Moreover, the manufacturers have already removed approximately 40
of the applications for these pesticides from their labels.
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
ETU 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 ETU has a medium potential to be transported, and a
medium potential to be transformed.
ETU migration into ground water could result from the presence of ETU in the
soil due to applications of EBDC pesticides on agricultural land. EBDC pesticides
could also reach ground water from direct entry into a well through accidental
chemical spills or improper storage near a well.
WPS Ethylene Thiourea
Printed on Recycled Paper
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Findings of Based on the results of the NPS, EPA estimates that ETU is present, at or above
the National the analytical detection level of 4.5 pg/L used in the Survey, in about 8,470 (0.1 %)
Pesticide rural domestic wells nationwide. Considering the precision of the Survey, EPA
S estimates that this number could be as high as 111,000 wells. ETU is measured in
urvey micrograms per liter (pg/L) which is equivalent to parts per billion (ppb). ETU was
detected at concentrations above the one-in-a-million lifetime cancer risk exposure
level of 0.2 pg/L. ETU was not detected in any CWS wells
What Health Non-Cancer Effects: A Lifetime Health Advisory Level for ETU in drinking water has
Effects Might not been established by EPA However, consuming ETU has been shown to result in
be Caused by damage to the thyroid gland, genetic mutation, anci birth defects in animal studies.
ETU m Cancer Risk: ETU also causes cancer in laboratory animals that are given high doses
Drinking of the chemical over the course of their lifetimes. Therefore, ETU is considered by
Water? EPA to be a probable human carcinogen (cancer-causing agent). EPA estimates that
if an individual consumes water containing ETU at 0.2 pg/L over his or her entire
lifetime, that person would theoretically have about a one-in-a-million chance of
developing cancer as a direct result of drinking water containing ETU.
Standard: EPA sets enforceable standards for public water systems, called Maximum
Contaminant Levels (MCLs). These regulatory standards set achievable levels of
drinking water quality to protect human health. EPA has not established a MCL for
ETU, but plans to list ETU on the Drinking Water Priority List for future MCL
consideration.
How is Water ETU can be detected in drinking water by using a laboratory method such as
Treated to Method #6 developed for the Survey If ETU is detected in well water and confirmed
Remove by retesting, State or County health officials should be consulted. They may advise
periodic retesting to get an accurate overall picture of the water quality because
on ami- changes in seasonal precipitation and changes in pesticide use can cause variations
nants? 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.
You may also be able to treat your well water to remove pesticides and other
contaminants. At present, EPA has no information on treatment technologies that can
effectively remove ETU from water. Based on the chemical and physical properties of
ETU, EPA believes that treatment by ion exchange or aeration may not be effective.
How Can Several steps may be taken to prevent pesticides or nitrate from entering wells,
Water such as eliminating direct entry through the well wall, drilling a new well, or modifying
Contamina- or reducing pesticide and fertilizer use.
tion be Eliminate Direct Entry Through the Well Wall
Prevented?
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 wall 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.
2 NPS Ethylene Thiourea
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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 agricultural 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.
Why was the EPA conducted this Survey to determine the frequency and concentration of
National pesticides, pesticide degradates, and nitrate in drinking water wells nationwide and to
Pesticide examine the relationship between the presence of pesticides in drinking water wells
and patterns of pesticide use and ground-water vulnerability. The Survey sampled
urvey 566 community water system wells and 783 rural domestic wells for 127 pesticides,
Conducted? 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.
Where to Go This fact sheet is part of a series of NPS outreach materials, fact sheets and
for More reports. The following additional fact sheets are available through EPA ’s Public
In formation Information Center (401 M Street SW, Washington DC 20460, (202) 382-2080):
Survey Design Analytical Methods Project Summary
Survey Analytes Summary Results Glossary
Quality Assurance/ Fact Sheet for each How EPA Will Use
Quality Control detected analyte The NPS Results
Additional information on the Survey and on pesticides in general can be
obtained from the following sources:
U.S. EPA Safe Drinking Water Hotline Information on regulation of
1 -800-426-4791 (In Washington, DC (202) 382-5533) pesticides in drinking
Monday-Friday, 8:30 am to 4:30 pm Eastern Time water
National Pesticide Telecommunications Network Information on health
1 -800-858-7378 effects and safe
24 hours a day handling of pesticides
U.S. EPA Office of Pesticide Programs (OPP) Docket Background documents
401 M Street, SW Room NE0004 for Survey (available
Washington, DC 20460 for review)
(202) 382-3587
NPS Ethylene Thiourea 3
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National Technical Information Service (NTIS) Copies of the
5285 Port Royal Road NPS Phase I Report
Springfield, VA 22161 (available 1991)
(703) 487-4650 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 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.
4 NPS Ethylene Thiourea
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