Technical Factsheet on: CHLOROBENZENE
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication:
National Primary Drinking Water Regulations
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: For a 10-kg (22 lb.) child
consuming 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 manufacture 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 Chemical Release Inventory, chlorobenzene releases to water totalled
over 326,000 lbs. Releases to land totalled nearly 37,000 lbs. These releases were primarily from alkali
and chlorine industries which use chlorobenzene in chlorination processes. Most of these releases
occurred in West Virginia.
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
biodegradation in the soil or water.

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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 groundwater. 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 mineralizing 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 hydrocarbon 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,
depending 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 1 to 2 for several species of
fish.
Primary human exposure is from ambient air, especially near point sources.
Chemical/Physical Properties
CAS Number: 108-90-7
Color/ Form/Odor: Colorless liquid with a faint, almond-like, aromatic odor
M.P.: -45.6C B.P.: 132 C
Vapor Pressure: 11.8 mm Hg at 25 C
Octanol/Water Partition (Kow): Log Kow = 2.18 to 2.84
Density/Spec. Grav.: 1.11 at 20 C
Solubilities: 0.45 g/L in water
Soil sorption coefficient: N/A
Odor/Taste Thresholds: N/A
Bioconcentration 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
Other Regulatory Information
Monitoring:
- For Ground/Surface Water Sources:

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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	Method Numbers
EPA 600/4-88-039	502.2; 524.2
Treatment/Best Available Technologies: Granular Activated Charcoal and Packed Tower Aeration
Toxic Release Inventory - Releases to Water and Land, 1987 to 1993 (in pounds):
Water	Land
TOTALS (in pounds)	326,017 36,910
Top Five States*
WV	262,653 263
OH	20,598 12,500
NJ	13,710 13,261
LA	16,460 265
SC	1,401 5,939
Major Industries
Alkalis, chlorine	261,058 67
Plastics, resins	23,756 13,312
Cyclic crudes, dyes	21,657 6,637
Indus, organics	13,460 9,375
Gum, wood chems	0 4,909
* Water/Land totals only include facilities with releases greater than a certain amount - usually 1000 to
10,000 lbs.
For Additional Information
EPA can provide further regulatory or other general information:
EPA Safe Drinking Water Hotline - 800/426-4791
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

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