oEPA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA 600 2-79-210g
Laboratory December 1979
Cincinnati OH 45268
Research and Development
Status
Assessment of
Toxic Chemicals
Hexachlorobenzene
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2 Environmental Protection Technology
3 Ecological Research
4. Environmental Monitoring
5 Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8, "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
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EPA-600/2-79-210g
December 1979
STATUS ASSESSMENT OF TOXIC CHEMICALS:
HEXACHLOROBEN Z ENE
by
T. R. Blackwood
Monsanto Research Corporation
Dayton, Ohio 45407
and
T. G. Sipes
Radian Corporation
Austin, Texas 78766
Contract No. 68-03-2550
Project Officer
David L. Becker
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory - Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effi-
ciently and economically.
This report contains a status assessment of the air
emissions, water pollution, health effects, and environmental
significance of hexachlorobenzene. This study was conducted
to provide a better understanding of the distribution and
characteristics of this pollutant. Further information on this
subject may be obtained from the Organic Chemicals and Products
Branch, Industrial Pollution Control Division.
Status assessment reports are used by lERL-Ci to communi-
cate the readily available information on selected substances to
government, industry, and persons having specific^needs and
interests. These reports are based primarily on data from open
literature sources, including government reports. They are
indicative rather than exhaustive.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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ABSTRACT
Hexachlorobenzene (HCB) can be produced as either a waste or a
byproduct from fourteen types of industrial processes. Although
1,450 metric tons were produced in 1975, present HCB production
and use quantities are unknown. Emissions from manufacture are
unknown.
Residues from the manufacture of chlorinated solvents and pes-
ticides represent the most prominent source of HCB, and the
emissions are estimated at 1,000 to 3,900 metric tons/yr. Air
and water, near waste-containing-HCB disposal sites have been
observed to contain up to 24 yg/m3 and 90 mg/m3 of HCB, respec-
tively. Soil samples near these same sites contain from 11 yg/g
to 3,000 yg/g. Due to the persistence of HCB, levels do not
decline rapidly.
Present control methods consist of incineration, deep-well injec-
tion, and landfill. Incineration is most effective at 1,300°C
and 0.25 s. While these control methods could be applied to
current waste streams, environmental pollution from past HCB
waste holding areas may represent a continuing problem because
HCB is stable and sublimes in air.
The only existing regulations on HCB are prohibition of ocean
dumping and limiting HCB in animal carcasses to 0.5 ppm.
Future studies should include confirmation of production quanti-
ties and use along with emissions estimates, concentrations in
pesticides and chlorinated solvents, and methods for removing
HCB from wastes such as sludges and wastewater. HCB has been
used as a fungicide in the United States with more than 6.9
metric tons used in 1971. Concern over the safety of HCB use,
in late 1972, may have eliminated continued use of HCB in grain
or food chain products.
This report was submitted in partial fulfillment of Contract
68-03-2550 by Monsanto Research Corporation under the sponsorship
of the U.S. Environmental Protection Agency. This report covers
the period November 1, 1977 to December 31, 1977. The work was
completed as of January 20, 1978.
IV
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CONTENTS
Foreword iii
Abstract iv
Conversion Factors and Metric Prefixes vi
Acknowledgement vii
1. Introduction 1
2. Summary 2
3. Source Description 5
Chemical and physical properties 5
Production 5
Process description 6
Uses 8
Transportation 8
4. Environmental Significance and Health Effects .... 9
Environmental significance 9
Health effects 13
5. Control Technologies 15
6. Regulatory Action in Progress 17
References 18
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CONVERSION FACTORS AND METRIC PREFIXES1
CONVERSION FACTORS
To convert from
Degree Celsius (°C)
Kilogram (kg)
Kilometer2 (km2)
Meter3 (m3)
Meter3 (m3)
Metric ton
Pascal (Pa)
to
Degree Fahrenheit (°F)
Pound-mass (pound-mass
avoirdupois)
Mile2
Foot3
Gallon (U.S. liquid)
Pound-mass
Pound-force/inch2 (psi)
Multiply by
t« = 1.8 t° + 32
2.204
3.860 x 10"1
3.531 x 101
2.642 x 102
2.205 x 103
1.450 x IQ-1*
METRIC PREFIXES
Prefix Symbol Multiplication factor
Centi
Kilo
Milli
c
k
m
io-2
103
io-3
Example
1
1
1
cm =
kg =
mm =
1
1
1
x
x
X
10-
103
10"
2
3
meter
grams
meter
Standard for Metric Practice. ANSI/ASTM Designation:
E 380-76e, IEEE Std 268-19,76, American Society for Testing and
Materials, Philadelphia, Pennsylvania, February 1976. 37 pp.
VI
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ACKNOWLEDGEMENT
This report was assembled for EPA by Radian Corporation, Austin,
TX, and Monsanto Research Corporation, Dayton, OH. Mr. D. L.
Becker served as EPA Project Officer, and Dr. C. E. Frank, EPA
Consultant, was principal advisor and reviewer.
VII
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SECTION 1
INTRODUCTION
Hexachlorobenzene (HCB) is toxic to man and has been shown to
cause liver tumors and dysfunction in hamsters. It is only
marginally produced in the United States and generally as a
byproduct of other chlorinated hydrocarbons manufacture. Con-
cern over HCB in the environment was heightened by high levels
found in beef cattle in 1972. The purpose of this report is to
summarize existing information on the production, uses, emis-
sions, health effects, control technology, and regulatory action
with respect to HCB. The fate and route of HCB in the environ-
ment is also summarized.
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SECTION 2
SUMMARY
Serious incidents of environmental contamination have been
observed involving hexachlorobenzene (HCB) wastes and products.
Despite steps to reduce environmental discharges of hexachloro-
benzene, environmental contamination persists. HCB is toxic to
man and presents a hazard in the environment. It is highly
resistant to chemical, biological, and physical degradation and
is persistent throughout the environment. It is apparently
accumulated in food chains. There are recent reports of the
occurrence of hexachlorobenzene in human adipose tissues (95% of
those sampled), the food supply, industrial effluents, and
drinking water. Hexachlorobenzene has recently been shown to be
a carcinogen in hamsters. Its chronic toxic effects are exhi-
bited by liver dysfunction in these animals.
Hexachlorobenzene is not a significant item of commerce and is
not produced as a direct product of a commercial process. It is
a specialty chemical which may be recovered as a byproduct.
Whether there are any current uses of HCB or whether byproduct
HCB is currently recovered for commercial use or distribution is
unknown. In 1975, 1,450 metric tons3 were reported to be pro-
duced in the United States.
It has been observed that HCB may transport through the environ-
ment due to sublimation from wastes containing HCB. For this
reason, waste disposal practices are under scrutiny.
Industrial wastes from manufacture of chlorinated hydrocarbons
in the solvents and pesticides industries are the major source
of HCB emissions. Emissions estimates range from 1,000 to
3,900 metric tons/yr. These emissions could be reduced by
incineration of wastes. Adequate disposal methods appear to be
available. A management plan to define regulatory action for
control of HCB emissions would have to be directed toward waste
streams from organic solvent and pesticide manufacture.
Table 1 summarizes important findings of this assessment on
emission sources, extent of the problem, control methods, and
regulatory action.
al metric ton = 106 grams; conversion factors and metric system
prefixes are presented in the prefatory pages of this report.
2
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TABLE 1. HEXACHLOROBENZENE
Emission source
Extent of problem
Control methods Regulatory action
u>
Production of hexachloro-
benzene
Waste disposal at chlorine,
carbon tetrachloride, per-
chloroethylene, trichloro-
ethylene, Dacthal, atrazine,
propazine, simazine, vinyl
chloride, pentachloronitro-
benzene, hexachloroethane,
diethyl tetrachlorotere-
phthalate, mirex, and other
chlorinated hydrocarbon pro-
ducing plants.
Uses include: grain fungi-
cide, pyrotechnic compound
chemical intermediate, wood
preservative, feedstock for
pentachlorophenol, and pep-
tizing agent in rubber
manufacture.
Over 100 sites across U.S.
may have produced HCB as a
by-product or waste.
Airconcentrations of 1 yg/m3
to 24 yg/m3, observed
waste disposal sites.
Water concentrations of
1 mg/m3 to 90 mg/m3
observed in wastewaters
leaving these plants.
Soil samples taken beyond
plant boundaries varied
from 11 yg/g to 3,000 yg/g.
From 1,000 to 3,900 metric
tons of HCB are estimated
to be emitted per year
(1972 to 1977).
6.9 metric tons used as
grain fungicide in 1971.
Incineration at
high tempera-
ture (l,300°c
and 0.25 s).
Deep-well
injection.
Landfill using
barriers and
1 m to 2 m of
cover.
In 1973, an interim
tolerance of 0.5 ppm
was set for HCB con-
tent in animal car-
casses by the EPA.
The state of Louisiana
required better solid
waste disposal
practices.
Dacthal and other pes-
ticides containing
HCB are under review
by EPA.
Ocean dumping of HCB-
laden wastes is
prohibited.
Designated a priority
pollutant under the
Federal Water Pollu-
tion Control Act.
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Based upon information presented in this report, the following
items need to be considered in future studies:
• Determination of the concentration of HCB in various
pesticide products such as atrazine, propazine, simazine,
Dacthal, pentachloronitrobenzene, or mirex.
• Methods for removing HCB from wastes such as sludges
and process wastewater.
• Identification of the amount of HCB used in dye manufac-
ture, organic synthesis, and rubber manufacture as well
as its use as a grain fungicide and wood preservative.
• Identification and production quantity of locations, if
any, which presently manufacture HCB.
• The potential for chronic effects at low-level exposure
of hexachlorobenzene.
• Methods to contain or treat existing HCB which has been
disposed as waste in landfill from chlorinated solvents
manufacture.
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SECTION 3
SOURCE DESCRIPTION
CHEMICAL AND PHYSICAL PROPERTIES
Hexachlorobenzene or perchlorobenzene (Cede) is a white powder
that is soluble in benzene, ethyl ether, and chloroform; spar-
ingly soluble in cold alcohol; and insoluble in water. It has
a molecular weight of 284.80, a melting point of 227°C, boiling
point of 325°C, and flash point of 243°C. It sublimes rapidly
at ambient temperatures, 0 to 30°C (1, 2).
PRODUCTION
Hexachlorobenzene (HCB) is a specialty chemical recovered as a
byproduct from proprietary chlorinated hydrocarbon processes (3).
Two companies produced HCB in 1976 (4). These were Hummel
Chemical Co., Inc., in South Plainfield, New Jersey and Dover
Chemical Corp. in Dover, Ohio. Stauffer Chemical Company has
also produced HCB in recent years. Recent information indicates
that HCB is no longer produced at these sites (5); however, the
1977 Buyers Guide issue of "Chemical Week" lists three producers
(1) Stecher, P. G., M. Windholy, D. S. Leathy, D. M. Bolton,
and L. G. Eaton. The Merck Index, Eighth Edition. Merck
and Company, Inc., Rahway, New Jersey, 1968.
(2) Hawley, G. G. Condensed Chemical Dictionary. Eighth
Edition. Van Nostrand Reinhold Co., New York, New York,
1971.
(3) Mumma, C. E., and E. W. Lawless. Survey of Industrial
Processing Data. Task 1 - Hexachlorobenzene and Hexa-
chlorobutadiene Pollution from Chlorocarbon Processing.
EPA-560/3-75-003, U.S. Environmental Protection Agency,
Washington, D.C., June 1976. 187 pp.
(4) 1977 Directory of Chemical Producers United States of
America. Stanford Research Institute, Menlo Park, Cali-
fornia, 1977. 1059 pp.
(5) 1977 Directory of Chemical Producers United States of
America. January to September Supplement. Stanford
Research Institute, Menlo Park, California, 1977. 73 pp.
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of HCB: Dover Chemical Corporation; Rhodia, Incorporated, Chemi-
cal Division; and Stauffer Chemical Company, Industrial Chemicals
Division (6).
Only occasional and fragmentary production statistics are pub-
lished for higher chlorobenzenes, such as hexachlorobenzene.
A data base prepared by Radian Corporation listed HCB production
as 1,450 metric tons in 1975 (7).
PROCESS DESCRIPTION
Methods for production of HCB are proprietary and limited infor-
mation is available. At Stauffer Chemical in Louisville, Ken-
tucky, HCB has been recovered from a byproduct that contains 80%
HCB. The remainder of the tar is recycled to the process.
Processes for direct production of HCB use either benzene or
hexachlorocyclohexane (C6H6Cl6) as the raw materials.
In one of the basic processes, benzene is reacted with excess
chlorine in the presence of ferric chloride at 150°C to 200°C as
shown in Figure 1. The reaction products are scrubbed with
water to remove hydrogen chloride. The gaseous chlorobenzenes
are recycled to the initial reactor. The reaction products are
cooled to 100°C to allow the HCB to crystallize (3). A contin-
uous process for HCB production by this method has been patented
by Olin Mathieson Corporation (8).
In another major process, isomers of hexachlorocyclohexane are
refluxed with sulfuryl chloride (S02C12) or chlorosulfonic acid
(HC1S03). A ferric chloride or an aluminum chloride catalyst
is employed. Reaction temperatures are 130°C to 200°C. The
reaction mixture is cooled to crystallize the HCB, which is fil-
tered, centrifuged, and washed. A schematic for this process is
given in Figure 2 (3).
Hexachlorobenzene is formed as a byproduct of hexachloroethane
production and is also produced as one of a group of coproducts
formed when ethylene is substituted for methane in the Huls
process for carbon tetrachloride production (8). In addition,
HCB can be produced as a byproduct, waste, or impurity with the
following chemicals: chlorine, perchloroethylene, trichloro-
ethylene, Dacthal, atrazine, propazine, simazine, vinyl chlo-
ride, pentachloronitrobenzene, and Mirex (3).
(6) 1977 Buyers Guide. Chemical Week, 119(17), 1976.
(7) Garner, D. N. and P. S. Dzierlenga. Organic Chemical Pro-
ducers' Data Base Program. Radian Corporation, Austin,
Texas, 1976.
(8) Kirk-Othmer Encyclopedia of Chemical Technology, Second Edi-
tion, Vol. 5. John Wiley & Sons, Inc., New York, New York,
1964. 884 pp.
6
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BYPRODUCT
HCI
CI2
PRIMARY REACTOR
WITH FeCI3
AS CATALYST
CRYSTALLIZER
PARTIALLY CHLORINATED BENZENES
SEPARATION
DRYING
PACKAGING
SHIPMENT OF SHIPMENT OF
LESS CHLORINATED HEXACHLOROBENZENE
BENZENES
PENTACHLOROBENZENE, ETC.
Figure 1. Production schematic for hexachlorobenzene by
chlorination of benzene and chlorobenzenes (3).
W<6
ISOMERS *
CHLOROSULFONIC ACID
OR SULFURYL CHLORIDE "~
REFLUX-
CONDENSER -
REACTOR WITH FeCI3
AS CATALYST
COOLER
FILTER
DRYING
PACKAGING
- SHIPMENT
HEXACHLOROBENZENE
Figure 2. Production schematic for hexachlorobenzene
from hexachlorocyclohexane (3).
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USES
Hexachlorobenzene has been used in the past as a fungicide to
control wheat bunt and smut fungi of grains. The U.S. Department
of Agriculture estimated that about 6.9 metric tons of HCB was
used in 1971 as a grain fungicide, principally in Washington,
Oregon, and California (9). It is not clear whether HCB is still
used as a grain fungicide.
Several other uses for HCB have been reported, but may not be
current. These applications include the use of HCB as an addi-
tive for pyrotechnic compounds, a porosity controller, a chemical
intermediate in dye manufacture and organic synthesis, and a
wood preservative. Hexachlorobenzene is also reportedly used as
a peptizing agent in nitroso and styrene type rubber manufactur-
ing. It has been used as a feedstock in the production of pen-
tachlorophenol, but this process is no longer in use in the
United States. Current estimates of the amounts of HCB used are
unavailable (3, 8, 10, 11, 12).
TRANSPORTATION
HCB wastes are transported by forklift truck, pipeline, heated
tank trucks, and railcars. Prior to ultimate disposal they are
stored as solid waste cubes under plastic cover and in water-
covered lagoons (13). Diamond Shamrock in Deer Park, Texas,
transports HCB-containing wastes to off-site disposal facilities.
The wastes are packaged in sealed containers before being shipped
(3).
HCB powder used as a fungicide would have to be transported from
its production site to the location where it is used, most likely
in small drums. Improper containment during transport can result
in HCB emissions into the air via sublimation or dust kickup.
HCB emitted during transportation can contaminate soil and water
and settle on the surface of vegetation (10).
(9) Assessing Potential Ocean Pollutants. National Academy of
Sciences, Washington, D.C., 1975.
(10) Environmental Contamination from Hexachlorobenzene.
EPA-560/6-76-014, U.S. Environmental Protection Agency,
Washington, D.C., July 1973. 34 pp.
(11) Wilkins, G. E. End Use Patterns for Significant Organic
Chemicals. Radian Corporation, Austin, Texas, July 21,
1976.
(12) Chemical Origins and Markets. G. M. Lawler, ed. Stanford
Research Institute, Menlo Park, California, 1967.
(13) Journal of Hazardous Materials, 1 (4):343-359, March 1977.
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SECTION 4
ENVIRONMENTAL SIGNIFICANCE AND HEALTH EFFECTS
ENVIRONMENTAL SIGNIFICANCE
Sources of Emissions
Fourteen types of industrial processes produce HCB as a waste or
byproduct (13). In processes where hexachlorobenzene is re-
covered as a byproduct, HCB is recovered or recycled to the
process. The majority of HCB containing wastes is produced in
pesticide and chlorinated solvent manufacture, Processes for
the production of perchloroethylene, trichloroethylene, carbon
tetrachloride, other chlorinated hydrocarbons, and pesticides
produce HCB containing wastes. This waste is in the form of a
heavy, tarry residue which contains chlorinated hydrocarbons
including HCB. The wastes from perchloroethylene and carbon
tetrachloride production reportedly contain 10% to 15% HCB and
are disposed in waste dumps. The dumps are then sources of HCB
which may be leached or sublimed into the environment.
Production of chlorine gas by electrolysis of NaCl with a graph-
ite anode and mercury cathode may also release HCB. In addition,
HCB is contained as a significant contaminant in the pesticides
diethyl tetrachloroterephthalate and pentachloronitrobenzene (3,
9, 10). It may also be present in other pesticides. Since HCB
sublimes, the use of pesticides may be an important source of
HCB. No confirmatory data are available.
Estimated production of HCB wastes is given in Tables 2 and 3.
According to one estimate, production of perchloroethylene
accounts for about 72% of all HCB formed in the United States
and production of carbon tetrachloride, perchloroethylene and
trichloroethylene accounts for 89% (3). Results published in
1977 (Table 3) indicate that chlorinated solvent production
accounts for about 60% of HCB wastes (13).
Hexachlorobenzene can also be emitted directly into the air from
production processes for HCB (10); however, one study shows
waste holding areas were often the most significant emission
source within the plant area (3).
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TABLE 2. ESTIMATED TOTAL QUANTITY OF HEXACHLOROBENZENE
CONTAINED IN U.S. INDUSTRIAL WASTES, BYPRODUCTS,
AND PRODUCTS IN 1972 (3)
Estimated HCB
U.S. production, produced, metric tons
Product 1,000 metric tons High Low
Perchloroethylene 334 1,590 794
Trichloroethylene 194 204 104
Carbon tetrachloride 453 182 90
Chlorine 8,660 177 73
Dacthal 0.9 45 36
Vinyl chloride 2,040 12 0
Atrazine, propazine,
simazine 51 42
Pentachloronitrobenzene 1.4 3 1
Mirex 0.4 0.9 0.4
TOTAL -a 2,200 1,010
Not applicable.
TABLE 3. ANNUAL VOLUME OF HCB WASTES FROM PESTICIDES
AND CHLORINATED SOLVENT INDUSTRIES IN 1977 (13)
Annual production
of HCB wastes,
Industry Products metric tons
Pesticide Dacthal, pentachloronitrobenzene, 1,500
mirex, simazine, atrazine,
propazine.
Industrial Chlorinated solvents. 2,400
organic
chemicals
Environmental Levels
The concentration of HCB in various media is primarily due to
solid- or semi-liquid wastes containing HCB. Although contami-
nated soil has been observed, it is believed to be caused by
particulate or vapor HCB in the air (14). In 1975, 46% of the
(14) Li, R. T., J. L. Spigarelli, and J. E. Going. Sampling and
Analysis of Selected Toxic Substances. Task 1A - Hexachlo-
robenzene. EPA-560/6-76-001, U.S. Environmental Protection
Agency, Washington, D.C., June 1976. 166 pp.
10
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soil samples collected at 26 locations along a 240 km transect in
Louisiana were contaminated with HCB at levels from 20 ppb (parts
per billion) to 440 ppb. Although water samples generally con-
tained less than 3 ppb, one sample downstream of an industrial
discharge contained 90 ppb. Air immediately adjacent to waste
dumps has shown concentrations from 1.0 yg/m3 to 24 yg/m3. Most
of the hexachlorobenzene appeared to be associated with particu-
late matter although some was found in the gas phase. This may
have resulted from volatilization of solid material. Samples
collected from pastureland near a known production site revealed
concentrations in the vegetation from 0.01 ppm (parts per mil-
lion) to 630 ppm and in the soil from 0.01 ppb to 300 ppb (10).
In 1974 and 1975, soil, water, and organism samples were col-
lected periodically from sites in southeastern Louisiana, with
emphasis along the Mississippi River and an industrial region of
known contamination near Geismar, Louisiana. Maximum HCB con-
centrations in water from the two areas were 90 mg/m3 and
75 mg/m3 (ppb). Maximum concentrations in soil were 874 yg/kg
and 53,130 yg/kg (ppb) (15).
Sampling tests at nine industrial plants representing six indus-
tries (perchloroethylene, trichloroethylene, carbon tetrachloride,
chlorine, triazine herbicides, and pentachloronitrobenzene)
showed HCB levels as high as 24 yg/m3 in the air and 306 mg/m3
in open wastewater treatment ponds. Levels of HCB in the soil
within plant boundaries were greater than 1,000 yg/g at three of
the plants sampled. The maximum concentration found in air
beyond these plant sites was 0.36 yg/m3; however, 3 yg/m3 was
detected at the boundary of another plant. Soil in a cornfield
adjacent to another plant site showed a concentration of 11 yg/g
and more than 3,000 yg/g was detected along the boundary road of
yet another plant. The observed HCB concentration in water
beyond plant property was more than 1 mg/m3 at two plants (14).
Hexachlorobenzene has been detected in rivers and chemical efflu-
ents at various locations (16). Hexachlorobenzene residues have
been found in soil, wildlife, fish, and food samples collected
from all over the world. In the United States, residues have
been reported in birds and bird eggs collected from Maine to
Florida, duck tissues collected from across the country, and fish
(15) Laseter, J. L., C. K. Bentell, A. L. Lacka, D. G. Holmquist,
D. B. Condie, J. W. Brown, and R. L. Evans. An Ecological
Study of Hexachlorobenzene (HCB). EPA-560/6-76-009, U.S.
Environmental Protection Agency, Washington, D.C., April
1976. 74 pp.
(16) Shackelford, W. M. and L. H. Keith. Frequency of Organic
Compounds Identified in Water. EPA-600/4-76-062, U.S.
Environmental Protection Agency, Athens, Georgia, December
1976. 629 pp.
11
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and fish eggs from the East Coast and Oregon. Animal foods,
including chicken feed, fish food, and general laboratory feeds,
have been found to contain residues. The frequency of detection
of residues in domestic meats has been steadily increasing since
1972, in part because of closer scrutiny. In 1972, beef cattle
carcasses in Louisiana were found to contain concentrations as
high as 1.5 ppm. The chemical has been detected in trace
amounts in only two drinking water supplies. EPA's monitoring
of human adipose tissues collected from across the United States
reveals that about 95% of the population has trace residues (10).
More information on levels of HCB residues found in aquatic
organizms and man is available in reports by the National Academy
of Sciences (9) and the Midwest Research Institute (3).
Reactions in the Environment
Hexachlorobenzene is a very stable, unreactive, and mobile com-
pound. It apparently does not undergo photochemical reactions
in the atmosphere, and it is not hydrolyzed in aqueous solutions.
There is no evidence that it is broken down by physical or chemi-
cal processes in the environment. It also appears to be largely
immune to the biological degradation process. Studies indicate
that it is not metabolized to any significant extent, but penta-
chlorobenzene is a possible metabolic derivative (9).
Since hexachlorobenzene is volatile over water, even at low
temperatures, codistillation is a method of dispersal. HCB also
sublimes readily and will evaporate if exposed to air under
adequate ventilation (9). It readily vaporizes from soil into
the air; emissions to the air can in turn contaminate more soil
(10). Aerial dispersal may be the major pathway for HCB entering
the marine environment (9).
Population Exposed
Hexachlorobenzene has been produced at Dover, Ohio, (estimated
population 11,200) South Plainfield, New Jersey, (population
21,300); Louisville, Kentucky (population 706,000) and possibly
at other locations. Because of the persistence of HCB, resi-
dents of these areas could be exposed to HCB residues resulting
from emissions from the plants even if the plants are not cur-
rently producing HCB.
Plants that produce HCB as a byproduct or waste are located at
over 100 sites throughout the country. Locations and production
capacities of these plants are given in a study by Midwest
Research Institute (3). (Most of these sites are located in
highly industrialized complexes in the South and eastern United
States.) Residents of areas near plants that produce HCB as a
byproduct or waste may be exposed to HCB emitted into the air or
contained in soil. Occupational exposure to HCB could affect
12
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workers at these plants as well as at the plants that directly
produce HCB.
HCB has been used as a grain fungicide, especially in Washington,
Oregon, and California (9). Because of the persistence of HCB,
residues of HCB could exist in soil where treated seed has been
planted. The population may also be exposed to HCB from the use
of pesticides such as Dacthal and pentachloronitrobenzene that
contain HCB as an impurity (9).
HEALTH EFFECTS
Effects on Humans
Evidence of the toxic effects of HCB for humans exists. The
death of breast-fed infants and an epidemic of skin sores and
skin discoloration were associated with accidental consumption
of hexachlorobenzene-contaminated seed grain in Turkey in the
mid-1950's. Doses were estimated at 50 to 200 ing/day for several
months to two years. Clinical manifestations included weight
loss, enlargement of the thyroid and lymph nodes, skin photo-
sensitization, and abnormal growth of body hair. Hexachloro-
benzene levels of up to 23 ppb in blood are believed to have
contributed to enzyme disruptions in the population of a small
community in southern Louisiana in 1973 (10).
Effects on Animals
Long-term (up to 3 years) animal ingestion studies show a
detectable increase in deaths at 32 ppm, cellular alteration at
1 ppm, and behavioral alteration between 0.5 ppm and 5 ppm.
Apparently, the effective dosage to offspring is increased by
exposure to the parent. A 12% reduction in offspring survival
results when exposure to very low levels had been continuous
for three generations. Teratogenic effects appear minimal (10).
A recent feeding study in hamsters showed that hexachlorobenzene
causes hepatomas (liver tumors) and hemangioendotheliomas (capil-
lary tumors). Doses of 50 ppm, 100 ppm, and 200 ppm of hexa-
chlorobenzene mixed with feed were used. Hepatomas were
observed at all dose levels, at rates and latencies appearing to
be dose related. Hemangioendotheliomas appeared only in the high
dose group (9% in females, 34% in males), and three of these
tumors in males metastacized (10).
Additional toxicological information on HCB is given in Table 4
(17).
(17) Registry of Toxic Effects of Chemical Substances, 1976
Edition. H. E. Christensen, E. J. Fairchild, eds. U.S.
Department of Health, Education, and Welfare, Rockville,
Maryland, June 1976. 1245 pp.
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TABLE 4. TOXIC EFFECTS OF HEXACHLOROBENZENE (17)
Oral lethal dose
(50 percent kill)
mg/kg body weight Animal
3,500 Rat
4,000 Mouse
1,700 Cat
2,600 Rabbit
Bioaccumulation in catfish has been observed to be extremely
high, and the half-life in cattle and sheep is almost 90 days
(10).
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SECTION 5
CONTROL TECHNOLOGIES
The major source of environmental contamination from HCB is
wastes from plants producing other chemicals. Some work has
been done on the development of environmentally sound disposal
methods for waste containing HCB. A study by Midwest Research
Institute includes a survey of waste disposal techniques
practiced by industries that produce wastes containing HCB (3).
Three methods are currently being used for disposal of these
wastes: landfill, deep-well injection, and incineration.
High temperature incineration appears to be the best alternative.
Deep-well injection may create geological fractures resulting in
contamination of aquifers (3). Landfill disposal of wastes con-
taining HCB can lead to migration of HCB via water and sublima-
tion of HCB into the air (10). Virtually all the HCB can be
destroyed in high temperature incineration systems (3). Incin-
eration of chlorinated hydrocarbons such as HCB is generally
carried out at temperatures around 1,300°C with a retention time
of about 0.25 s. Several types of incinerators are available.
Most hexachlorobenzene waste is a viscous liquid at ambient
temperature and can be incinerated in rotary kiln incinerators
or in fluidized sand bed incinerators. Exhaust gases from in-
cineration must be scrubbed in high energy scrubbers with caus-
tic soda or lime solution to neutralize HC1 and other acids
evolved (3). Dow Chemicals uses a proprietary "thermal oxidizer"
(steam-oxygen fed incinerator) to incinerate wastes containing
HCB. Products of the incineration are hydrogen chloride, carbon
dioxide, and water. More than 99% of the HCB is reportedly
destroyed (10).
Plastic sheets are reportedly effective in reducing particulate
emissions of HCB from waste storage areas, but vapor emissions
of HCB from such areas may still be high. Hexachlorobenzene
content in water was reportedly reduced about 50% at two plants
sampled by detaining wastes in holding ponds or treatment canals
(14). A discussion and evaluation of methods used for treatment
15
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and disposal of wastes containing HCB is given in a report done
by TRW Corporation for EPA (18).
A recent report indicates that land disposal is the most preva-
lent disposal method. Land disposal was characterized as
environmentally acceptable if soil covers of 1 m to 2 m and
intermediate plastic layers were employed to reduce the sublima-
tion rate. Selection of a site with geological characteristics
that would provide for leachate containment is also necessary
(13).
(18) Quinlivan, S., M. Ghassemi, and M. Sontry. Survey of
Methods Used to Control Wastes Containing Hexachlorobenzene,
EPA-530/SW-120C, U.S. Environmental Protection Agency,
Washington, D.C., November 1975. 92 pp.
16
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SECTION 6
REGULATORY ACTION IN PROGRESS
In the wake of widespread hexachlorobenzene contamination of
cattle in Louisiana in 1973 and concern over possible contamina-
tion of sheep in California, EPA established an interim toler-
ance level of 0.5 ppm. Concurrently, the State of Louisiana and
several companies took immediate steps to improve solid waste
disposal practices from manufacturing. Also, supplies of Dacthal
containing 10% HCB were voluntarily withdrawn from the Cali-
fornia market.
As soon as the needed toxicological data are available, a food
tolerance will be established. Also, all pesticidal uses will
be reviewed, including pesticides which contain hexachloro-
benzene as a contaminant. Studies of land and other disposal
methods have been completed. Ocean dumping of hexachlorobenzene-
laden tars is prohibited (10).
It has also been designated a priority pollutant under the
Federal Water Pollution Control Act.
17
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REFERENCES
1. Stecher, P. G., M. Windholy, D. S. Leathy, D. M. Bolton,
and L. G. Eaton. The Merck Index, Eighth Edition. Merck
and Company, Inc., Rahway, New Jersey, 1968.
2. Hawley, G. G. Condensed Chemical Dictionary. Eighth
Edition. Van Nostrand Reinhold Co., New York, New York,
1971.
3. Mumma, C. E., and E. W. Lawless. Survey of Industrial
Processing Data. Task 1 - Hexachlorobenzene and Hexa-
chlorobutadiene Pollution from Chlorocarbon Processing.
EPA-560/3-75-003, U.S. Environmental Protection Agency,
Washington, D.C., June 1975. 187 pp.
4. 1977 Directory of Chemical Producers United States of
America. Stanford Research Institute, Menlo Park, Cali-
fornia, 1977. 1059 pp.
5. 1977 Directory of Chemical Producers United States of
America. January to September Supplement. Stanford
Research Institute, Menlo Park, California, 1977. 73 pp.
6. 1977 Buyers Guide. Chemical Week, 119(17), 1976.
7. Garner, D. N., and P. S. Dzierlenga. Organic Chemical
Producers' Data Base Program. Radian Corporation, Austin,
Texas, 1976.
8. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 18. John Wiley & Sons, Inc., New York,
New York, 1964. 884 pp.
9. Assessing Potential Ocean Pollutants. National Academy of
Sciences, Washington, D.C., 1975.
10. Environmental Contamination from Hexachlorobenzene.
EPA-560/6-76-014, U.S. Environmental Protection Agency,
Washington, D.C., July 1973. 34 pp.
11. Wilkins, G. E. End Use Patterns for Significant Organic
Chemicals. Radian Corporation, Austin, Texas, July 21,
1976.
18
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12. Chemical Origins and Markets. G. M. Lawler, ed. Stanford
Research Institute, Menlo Park, California, 1967.
13. Journal of Hazardous Materials, 1(4) :343-359, March 1977.
14. Li, R. T., J. L. Spigarelli, and J. E. Going. Sampling and
Analysis of Selected Toxic Substances. Task 1A - Hexachlo-
robenzene. EPA-560/6-76-001, U.S. Environmental Protection
Agency, Washington, B.C., June 1976. 166 pp.
15. Laseter, J. L., C. K. Bentell, A. L. Lacka, D. G. Holmquist,
D. B. Condie, J. W. Brown, and R. L. Evans. An Ecological
Study of Hexachlorobenzene (HCB). EPA-560/6-76-009, U.S.
Environmental Protection Agency, Washington, D.C., April
1976. 74 pp.
16. Shackelford, W. M., and L. H. Keith. Frequency of Organic
Compounds Identified in Water. EPA-600/4-76-062, U.S.
Environmental Protection Agency, Athens, Georgia, December
1976. 629 pp.
17. Registry of Toxic Effects of Chemical Substances, 1976
Edition. H. E. Christensen, E. J. Fairchild, eds. U.S.
Department of Health, Education, and Welfare, Rockville,
Maryland, June 1976. 1245 pp.
18. Quinlivan, S., M. Ghassemi, and M. Sontry. Survey of
Methods Used to Control Wastes Containing Hexachlorobenzene,
EPA-530/SW-120C, U.S. Environmental Protection Agency,
Washington, D.C., November 1975. 92 pp.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-210g
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Status Assessment of Toxic Chemicals
5. REPORT DATE
December 1979
Hexachloro-
benzene
issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
T.R. Blackwood,
T.G. Sipes
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corp Radian Corp
1515 Nichols Road 8500 Shoal Creek Blvd
Dayton, Ohio U5H07 P.O. Box 99U8
Austin, Texas 78766
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-03-2550
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio ^5268
- Cinn, OH
13. TYPE OF REPORT AND PERIOD COVERED
Task Final 11/77 - 12/77
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
IERL-Ci project leader for this report is Dr. Charles Frank, 513-6Qk-kkQl
16. ABSTRACT
The properties, production processes, uses, and emission sources for
hexachlorbenzene are explained in this report. The environmental
effects, health hazards, and current control technologies are discussed.
The problems of the longevity of the hexachlorobenzene molecule and
past hexachlorobenzene contamination are discussed and areas requiring
further study are pointed out.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Benzene, Aromatic Hydrocarbons, Aromatic
Monocyclic Hydrocarbons, Hydrocarbons,
Unsaturated Hydrocarbons, Chlorobenzenes
Solvents, Pesticides,
Fungicides
68A
68D
68G
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
28
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
PREVIOUS EDITION IS OBSOLETE
20
•i US GOVERNMENT PfllNTPNC OFFICE 1980-657-146/5512
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