Technical Factsheet on: 1,2,4-TRICHLOROBENZENE
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: 0.07 mg/L
MCL: 0.07 mg/L
HAL(child): 1 day: 0.1 mg/L; Longer term: 0.1 mg/L
Health Effects Summary
Acute: EPA has found 1,2,4-trichlorobenzene to potentially cause the following health effects from acute
exposures at levels above the MCL: changes in liver, kidneys and adrenal glands
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 0.1 mg/L.
Chronic: 1,2,4-Trichlorobenzene has the potential to cause the following health effects from long-term
exposures at levels above the MCL: increased adrenal gland weights
Cancer: There is presently no evidence that 1,2,4-Trichlorobenzene has the potential to cause cancer
from a lifetime exposure in drinking water.
Usage Patterns
Current production figures on 1,2,4-trichlorobenzene are not available. EPA estimated 1983 production to
be in the range of 3 to 8 million lbs. 1983 imports were reportedly over 3 million lbs.
1,2,4-Trichlorobenzene is primarily used as a dye carrier. Other uses include: an intermediate in the
manufacture of herbicides and higher chlorinated benzenes; dielectric fluid; solvent; heat-transfer
medium; degreasing agents; septic tank and drain cleaners; wood preservatives; and abrasive
formulations. It was once used as a soil treatment for termite control.
Release Patterns
Major environmental releases of 1,2,4-trichlorobenzene are due to its manufacture and use as a dye
carrier. 1,2,4-Trichlorobenzene is also a product of hexachlorobenzene dechlorination by anaerobic
sewage sludge.
From 1987 to 1993, according to EPA's Toxic Chemical Release Inventory, 1,2,4- trichlorobenzene
releases to land and water totalled over 180,000 lbs., of which about 87% was to water. These releases
were primarily from textile finishing industries. The largest releases occurred in North Carolina and
Virginia.
Environmental Fate

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If 1,2,4-trichlorobenzene (1,2,4-TCB) is released to the soil it will probably adsorb to the soil and therefore
will not leach appreciably to the groundwater. However, 1,2,4-TCB has been detected in some
groundwater samples which indicates that it can be transported there by some process. 1,2,4-TCB will
not hydrolyze or biodegrade in groundwater, but it may biodegrade slowly in the soil based upon the data
from one experiment.
If released to water it will adsorb to the sediments. It will not hydrolyze in surface waters but it may be
subject to significant biodegradation. It is expected to significantly evaporate from water with half-lives of
11-22 days for evaporation from a seawater microcosm and a half-life of 4.2 hr predicted for evaporation
from a model river. Adsorption to sediments or absorption by microorganisms may minimize the rate of
evaporation. A half-life of 450 years has been reported for sunlight photolysis in surface waters at 40 deg
latitude in summer.
If 1,2,4-trichlorobenzene is released to the atmosphere, it may react with photochemically produced
hydroxyl radicals with a resulting estimated vapor phase half-life in the atmosphere of 18.5 days.
Bioconcentration in aquatic organisms has been measured and values for fish ranging from 51 to 2800
have been reported.
Exposure to 1,2,4-trichlorobenzene will result mainly from occupational exposure during its manufacture
and use, while general population exposure will result from the ingestion of contaminated drinking water
and food, especially contaminated fish.
Chemical/Physical Properties
CAS Number: 120-82-1
Color/ Form/Odor: Aromatic, colorless liquid
M.P.: 17 C B.P.: 213.5 C
Vapor Pressure: 0.29 mm Hg at 25 C
Octanol/Water Partition (Kow): Log Kow = 4.02
Density/Spec. Grav.: 1.45 at 20 C
Solubility: 30 mg/L of water at 20 C; Slightly soluble in water
Soil sorption coefficient: Koc ranges from 1000 to 5000; moderate to high mobility in soil
Odor/Taste Thresholds: Odor threshold in water is 3 mg/L
Bioconcentration Factor: BCFs range from 490 to 2800 in fish; expected to bioconcentrate in aquatic
organisms.
Henry's Law Coefficient: 3.9x10-3 atm-cu m/mole
Trade Names/Synonyms: 1,2,4-Trichlorobenzol, Hostetex L-PEC
Other Regulatory Information

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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	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)	157,541	22,835
Top Five States*
NC	80,253	13,209
VA	36,970	0
GA	17,639	8,951
WV	20,300	0
NY	1,150	1
Major Industries*
Finishing plants, misc	52,249	0
Finishing plants, synth.	47,976	0
Weaving, finishing mills	20,139	8,951
Alkalies, chlorine	21,773	1
Knitting mills, misc	9,077	9,994
Knit outerwear mills	1,300	3,200
* Water/Land totals only include facilities with releases greater than 100 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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