United States
Environmental Protection
Agency
&EPA
Office of Water
4601
EPA 811-F-95-004d-T
October 1995
National Primary Drinking
Water Regulations
Chlorobenzene
CHEMICAL/ PHYSICAL PROPERTIES
OCTANOL/WATER PARTITION (Kow):
Log Kow = 2.18 TO 2.84
CAS NUMBER: 108-90-7
DENSITY/SPEC. GRAV.: 1.11 at 20° C
COLOR/ FORM/ODOR: Colorless liquid with a
faint, almond-like, aromatic odor SOLUBILITIES: 0.45 g/L in water
M.P.:-45.6°C B.P.: 132° C
VAPOR PRESSURE: 11.8 mm Hg at 25° C
SOIL SORPTION COEFFICIENT: N/A
ODOR/TASTE THRESHOLDS: N/A
BlOCONCENTRATION FACTOR (BCF):
Log BCF = 1 to 2 in fish;
not significant
HENRY'S LAW COEFFICIENT:
0.00356 atm-cu m/mole (calculated)
TRADE NAMES/SYNONYMS:
Benzene chloride, Chlorbenzol,
Monochlorobenzene, Phenyl chloride,
IP Carrier T 40, Tetrosin SP
DRINKING WATER STANDARDS
MCLG: 0.1 mg/L
MCL: 0.1 mg/L
HAL: 1 to 10 day: 2 mg/L
Longer-term: 2 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found chlorobenzene to potentially
cause anesthetic effects and impaired liver and kidney
function from short-term exposures at levels above the
MCL.
Drinking water levels which are considered "safe" for
short-term exposures: Fora 10-kg (22 Ib.) child consum-
ing 1 liter of water per day: upto a 7-year exposure to 2
mg/L.
Chronic: Chlorobenzene has the potential to cause
liver, kidney and central nervous system damage from
long-term exposure at levels above the MCL.
Cancer: There is inadequate evidence to state whether
or not chlorobenzene has the potential to cause cancer
from a lifetime exposure in drinking water.
USAGE PATTERNS
Production of chlorobenzene in 1988 was 270 million
pounds, and was expected to decrease.
Uses of chlorobenzene include: an intermediate in the
nanufacture of other organic chemicals, dyestuffs and
insecticides (60%); as a solvent for adhesives, drugs,
rubber, paints and dry-cleaning (30%); miscellaneous
uses include fiber-swelling agent in textile processing.
RELEASE PATTERNS
Major environmental releases of chlorobenzene are
due to its use as a solvent in pesticides.
From 1987 to 1993, according to EPA's Toxic Chemi-
cal Release Inventory, chlorobenzene releases to water
totalled over 326,000 Ibs. Releases to land totalled nearly
37,000 Ibs. These releases were primarily from alkali and
chlorine industries which use chlorobenzene in chlorina-
tion processes. Most of these releases occurred in West
Virginia.
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
Water
TOTALS (in pounds) 326,017
Top Five States*
WV 262,653
OH 20,598
NJ 13,710
LA 16,460
SC 1,401
Major Industries
Alkalis, chlorine 261,058
Plastics, resins 23,756
Cyclic crudes, dyes 21,657
Indus, organics 13,460
Gum, wood chems 0
Land
36,910
263
12,500
13,261
265
5,939
67
13,312
6,637
9,375
4,909
* Water/Land totals only include facilities with releases
greater than a certain amount - usually 1000 to 10,000 Ibs.
October 1995
Technical Version
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ENVIRONMENTAL FATE
Chlorobenzene will enter the atmosphere from fugitive
emissions connected with its use as a solvent in pesticide
formulations and as an industrial solvent. Once released
it will decrease in concentration due to dilution and
photooxidation.
Releases into water and onto land will dissipate due to
vaporization into the atmosphere and slow biodegrada-
tion in the soil or water.
It is relatively mobile in sandy soil and aquifer material
and biodegrades very slowly or not at all in these soils.
Therefore, it can be expected to leach into the groundwa-
ter. It has a moderate adsorption onto organic soil. If
retained long enough, a large number of soil bacteria and
fungi are capable of degrading chlorobenzene and min-
eralizing it. 2- and 4-chlorophenol are products of this
biodegradation. Degradation will generally be slow, but
fairly rapid mineralization (20%/week) has been reported
in one study. Acclimation of soil microorganisms to hy-
drocarbon metabolism is an important factor.
In water, the primary loss will be due to evaporation,
with a half-life estimated at up to 10 to 11 hours, depend-
ing on the wind speed and water movement. The half-life
for evaporation is approximately 4.5 hours with moderate
wind speed.
Biodegradation will occur during the warmer seasons
and will proceed more rapidly in fresh water than in
estuarine and marine systems. Again, acclimation of soil
microorganisms is important. A moderate amount of
adsorption will occur onto organic sediments.
Little bioconcentration is expected into fish and food
products. Log BCF is 1to 2 for several species offish.
Primary human exposure is from ambient air, espe-
cially near point sources.
OTHER REGULATORY INFORMATION
MONITORING:
FOR GROUND/SURFACE WATER SOURCES:
INITIAL FREQUENCY- 4 quarterly samples every 3 years
REPEAT FREQUENCY- Annually after 1 year of no detection
TRIGGERS - Return to Initial Freq. if detect at > 0.0005 mg/L
ANALYSIS:
REFERENCE SOURCE
EPA 600/4-88-039
METHOD NUMBERS
502.2; 524.2
TREATMENT:
BEST AVAILABLE TECHNOLOGIES
Granular Activated Charcoal and Packed Tower Aeration
FOR ADDITIONAL INFORMATION:
* EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
4 Other sources of toxicological and environmental fate data include:
• Toxic Substance Control Act Information Line - 202/554-1404
Toxics Release Inventory, National Library of Medicine - 301/496-6531
• Agency for Toxic Substances and Disease Registry - 404/639-6000
October 1995
Technical Version
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