United States
Environmental Protection
Agency
Office of Water
Office of Pesticides and
Toxic Substances
Fall 1990
&EPA National Pesticide Survey
Hexachlorobenzene
ci
ci
Hexachlorobenzene
What is
Hexachloro-
benzene?
How Does
Hexachloro-
benzene
Behave in
Soil and
Ground
Water?
How Does
Hexachloro-
benzene 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. Hexachlorobenzene was one of the
pesticides detected in the Survey. This fact sheet provides a description of
hexachlorobenzene, its potential health effects, and guidance on both treating and
preventing well contamination,
Hexachlorobenzene (HCB) is the common name of a fungicide which was first
registered in the late 1940s/early 1950s, but is no longer registered. It has been sold
under the trade names of Anticarie, Ceku C.B., and No Bunt. Hexachlorobenzene was
also a component of the discontinued fungicide Veronit C. It was an ingredient of
pesticides used to control bunt (destructive smut fungus) on small grains such as
wheat. Hexachlorobenzene was also a seed protectant for use only on common
wheat bunt.
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
hexachlorobenzene 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. Hexachlorobenzene has a medium potential
to be transported, and a low potential to be transformed.
Hexachlorobenzene migration into ground water could result from its presence
in the soil due to agricultural applications. Hexachlorobenzene could also reach
ground water from direct entry into a well through accidental chemical spills or
improper storage near a well.
NPS Hexachlorobenzene
Printed on Recycled Paper
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Findings of
the National
Pesticide
Survey
What Health
Effects Might
be Caused by
Hexachloro-
benzene in
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 hexachlorobenzene is
present, at or above the analytical detection level of 0.060 fjg/L used in the Survey, in
about 470 (0.5%) CWS wells nationwide. Considering the precision of the Survey,
EPA estimates that this number could be as low as 61 or as high as 1,630.
Hexachlorobenzene is measured in micrograms per liter (/ug/L) which is equivalent to
parts per billion (ppb). Hexachlorobenzene was not detected at concentrations above
EPA's proposed Maximum Contaminant Level (MCL) of 1 mg/L Hexachlorobenzene
was not detected in any rural domestic wells.
Non-Cancer Effects: A Lifetime Health Advisory Level for hexachlorobenzene in
drinking water has not been established by EPA. Consuming hexachlorobenzene,
however, has been shown to result in adverse health effects in animal studies,
including damage to the liver, kidneys, ovaries, and skin, decreased fetal weight, and
adverse effects on the nervous system.
Cancer Risk: Hexachlorobenzene also causes cancer in laboratory animals that are
given high doses of the pesticide over the course of their lifetimes. Therefore,
hexachlorobenzene is considered by EPA to be a probable human carcinogen
(cancer-causing agent). EPA estimates that if an individual consumes water
containing hexachlorobenzene at 0.02 fjg/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 regulatory standards set achievable levels of drinking water quality to protect
human health. The proposed MCL for hexachlorobenzene is 1 fjg/L (proposed as of
July 25, 1990).
Hexachlorobenzene can be detected in drinking water by a laboratory using an
EPA method such as #508. If hexachlorobenzene is detected in well water and
confirmed by retesting to be above 0.02 yug/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 exceeds its MCL.
You may also be able to treat your well water to remove pesticides and other
contaminants. At present, activated carbon adsorption appears to be a possible
method for removing hexachlorobenzene from water. However, this technique is not
necessarily appropriate or available in every situation. 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
A/PS Hexachlorobenzene
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Why was the
National
Pesticide
Survey
Conducted?
Where to Go
for More
Information
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 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):
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
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
Information on regulation of
pesticides in drinking
water
Information on health
effects and safe
handling of pesticides
Background documents
for Survey (available
for review)
NPS Hexachlorobenzene
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National Technical Information Service (NTIS)
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
Copies of the
NFS Phase I Report
(available 1991)
and
NFS 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.
Worthing, Charles R., ed. The Pesticide Manual. 8th ed. Thornton Heath: The British
Crop Protection Council, 1987.
WPS Hexachlorobenzene
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