This is a fact sheet about a chemical that may be found in some public or
private drinking water supplies. It may cause health problems if found
in amounts greater than the health standard set by the United States
Environmental Protection Agency (EPA).
What is Hexachlorobenzene and how is it used?
Hexachlorobenzene (HCB) is an organic solid of white crystalline needles.
It is produced as a by-product from the manufacture of a variety of
other regulated organic chemicals. It is also a contaminant in the
production of some pesticides. The greatest use of HCB is in making
other organic compounds such as rubber, dyes, wood preservatives. Other
uses of include: as a fungicide on grains, especially wheat.
The list of trade names given below may help you find out whether you
are using this chemical at home or work.
Trade Names and Synonyms:
Julin's carbon chloride
No bunt 40
No bunt 80
Why is Hexachlorobenzene being regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires
EPA to determine safe levels of chemicals in drinking water which do or
may cause health problems. These non-enforceable levels, based solely on
possible health risks and exposure, are called Maximum Contaminant Level
The MCLG for HCB has been set at zero because EPA believes this
level of protection would not cause any of the potential health problems
Based on this MCLG, EPA has set an enforceable standard called a
Maximum Contaminant Level (MCL). MCLs are set as close to the MCLGs as
possible, considering the ability of public water systems to detect and
remove contaminants using suitable treatment technologies.
The MCL has been set at 1 part per billion (ppb) because EPA
believes, given present technology and resources, this is the lowest
level to which water systems can reasonably be required to remove this
contaminant should it occur in drinking water.
These drinking water standards and the regulations for ensuring
these standards are met, are called National Primary Drinking Water
Regulations. All public water supplies must abide by these regulations.
What are the health effects?
Short-term: EPA has found HCB to potentially cause the following health
effects when people are exposed to it at levels above the MCL for
relatively short periods of time: skin lesions, nerve and liver damage.
Long-term: HCB has the potential to cause the following effects
from a lifetime exposure at levels above the MCL: damage to liver and
kidneys; reproductive effects; benign tumors of endocrine glands;
How much Hexachlorobenzene is produced and released to the environment?
In 1982, imports were reported to be 38,000 lbs, with no evidence of
commercial domestic production. However, 2 to 5 million lbs may be
generated each year as a waste by-product of chlorination processes in
Major environmental releases of HCB are due to air and water
discharges from its production as a by-product of chemical manufacture,
or from pesticide applications. It is also released by some waste
incineration processes. It has been detected in treated waste water from
non-ferrous metal manufacturing.
From 1987 to 1993, according to EPA's Toxic Chemical Release Inventory,
HCB releases to land and water totalled 1,287 lbs., all of which was to
water. These releases were primarily from alkali, chlorine and
agricultural chemical industries. The largest releases occurred in
Louisiana and Texas.
What happens to Hexachlorobenzene when it is released to the environment?
HCB is a very persistent environmental chemical due to its chemical
stability and resistance to break down by microbes in soil or water. HCB
strongly to soils and to lake and river sediments. It is not likely to
migrate through soil to ground water.
Hexachlorobenzene will accumulate in fish. It has been detected in food
during market basket surveys.
How will Hexachlorobenzene be detected in and removed from my drinking
The regulation for HCB became effective in 1994. Between 1993 and 1995,
EPA required your water supplier to collect water samples every 3 months
for one year and analyze them to find out if HCB is present above 0.1
ppb. If it is present above this level, the system must continue to
monitor this contaminant.
If contaminant levels are found to be consistently above the MCL,
your water supplier must take steps to reduce the amount of HCB so that
it is consistently below that level. The following treatment methods
have been approved by EPA for removing HCB: Granular activated charcoal.
How will I know if Hexachlorobenzene is in my drinking water?
If the levels of HCB exceed the MCL, 1 ppb, the system must notify the
public via newspapers, radio, TV and other means. Additional actions,
such as providing alternative drinking water supplies, may be required
to prevent serious risks to public health.
This is a factsheet about a chemical that may be found in some
public or private drinking water supplies. It may cause health problems
if found in amounts greater than the health standard set by the United
States Environmental Protection Agency (EPA).
Drinking Water Standards:
Note: This fact sheet is part of a larger publication
adapted from U.S. EPA publication: EPA National Primary Drinking Water
Mcl: 1 ppm (parts per million)