Urmeo States
Environmental Protection
Agency
Office of Water
Office of Pesticides ana
Toxic Substances
Fall 1990
&EPA National Pesticide Survey
Ethylene Thiourea
r-
CH,
Ethylene ThtourM
What It ETU?
How Does
ETU 8en«ve
In Soil and
Ground
Wattr?
How Dots
ETU Get Into
Ground
Wattr?
The U.S. Environmental Protection Agency (EPA) has completed Its five-year
National Survey of Pesticides in Drinking Water Weils (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 thtourea (ETU), a breakdown
product of ethyiene bisdithtocarbamate (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 thtourea is a degradation product of fungicides from the chemical
family of EBDCs. Common names of fungicides that produce ETU include Mancozeb,
Maneb, Metiram, and Zneb. 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 wed 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 earned off by surface runoff, be carried to ground
water through leaching, or remain in the soil through adsorption (adherence) to soil
particles and undergo tttle movement in air or water. Pesticides may be transformed
by reaction with water, microorgarHsms, and exposure to sunSght The likelihood that
ETU wfll migrate into ground water is influenced by its tendency to be transported
(move) from soi to air and water and to be transformed by these various processes,
as wen as by the characteristics of the site, such as son type, moisture, temperature,
•nd 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 resuk from the presence of ETU in the
son due to applications of EBDC pesticides on agricultural land. EBDC pesticides
could also reach ground water from direct entry into a wefl through accidental
chemical spills or improper storage near a well.
MPS Cthyfen* TMeuma
-------
Findings of
trie National
Pett/c/de
Survey
What Health
Effects Might
be Caused by
ETUIn
Drinking
Water?
How Is Water
Treated to
Remove
Contami-
nants?
How Can
Water
Contamina-
tion be
Prevented?
Based on the results of the NFS, EPA estimates that ETU is present, at or above
the analytical detection level of 4.5 yg/L used in the Survey, in about 8,470 (0.1%)
rural domestic wells nationwide. Considering the precision of the Survey, EPA
estimates that this number could be as high as 111,000 wells. ETU is measured in
micrograms per liter (yg/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.
Non-Cancer Effects: A Lifetime Health Advisory Level for ETU in drinking water has
not been established by EPA. However, consuming ETU has been shown to result in
damage to the thyroid gland, genetic mutation, and birth defects in animal studies.
Cancer Rl*k: ETU also causes cancer in laboratory animals that are given high doses
of the chemical over the course of their lifetimes. Therefore, ETU is considered by
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.
ETU can be detected in drinking water by using a laboratory method such as
Method #6 developed for the Survey. If ETU is detected in well water and confirmed
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
changes in seasonal precipitation and changes in pesticide use can cause variations
in the amount of chemicals found in water weHs. 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.
Several steps may be taken to prevent pesticides or nitrate from entering wells,
such as efiminating direct entry through the well wall, drilling a new well, or modifying
or reducing pesticide and fertilizer use.
fibnirwfe Direct Entry Through the W*H Wall
9 pertddea or nitrate are present in well water, they may be entering the
ground water through the wed Itself rather than through the soil. If the well is old or
poorly constructed, or I there are vtetole 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 wefl 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 spffl could lead to direct contamination of the well.
MPS ftfiyto* Tttlouni.
-------
Drill a New Will
Why was the
National
Pasticlde
Survey
Conducted?
Where to Go
for More
Information
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 Pe*t/c/0e 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 pan 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 Detlgn
Survey Ana/ytes
Quality Assurance/
Quality Control
Analytical Methods
Summary Resu/ft
Fact Sheet for each
detected ana/yte
Pro/ecf Summary
6/ossary
How EPA Will Ut9
The NPS ftesuft*
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 On 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
Public Information Branch (H7506C)
401 M Street, SW
Washitigton, DC 20460
Telephone: (703) 557-2805
Information on regulation of
pesticides in drinking
water
Information on hearth
effects and safe
handling of pesticides
Background documents
for Survey (available
for review)
NPS Rrtyftn* ThtourM
-------
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)
tf you are concerned about the presence of pesticides and nitrate in your
private water well, contact your local or Slate 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 suppfy 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 Hearth
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.
NPS Etftyf*n« Th/ourta
------- |