United States
Environmental Protection
Agency
Office of Water
4601
EPA 811-F-95-004f-T
October 1995
National Primary Drinking
Water Regulations
p-Dichlorobenzene
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 106-46-7
COLOR/ FORM/ODOR: White crystals with
distinctive aromatic, mothball-like odor
M.P.:53.1°C B.P.: 174° C
VAPOR PRESSURE: 10 mm Hg at 54.8° C
OCTANOL/WATER PARTITION (Kow):
Log Kow = 3.37
DENSITY/SPEC. GRAV.: 1.25 g/ml at 20° C
SOLUBILITIES: 65.3 mg/L of water at 25° C
SOIL SORPTION COEFFICIENT:
Koc estimates range from 409 TO
1514
ODOR/TASTE THRESHOLDS: N/A
BlOCONCENTRATION FACTOR (BCF):
Low; Ranges from 100 to 250 in
various species
HENRY'S LAW COEFFICIENT:
0.0015 atm-cu m/mole at 20° C
TRADE NAMES/SYNONYMS: Paradichloroben-
zene; Paradichlorobenzol; Paramoth;
Di-Chloricide; Paradi; Paradow; Persia-
Perazol; Evola; Parazene
DRINKING WATER STANDARDS
MCLG: 0.075 mg/L
MCL: 0.075 mg/L
HAL(child): 1 day: 10 mg/L
Longer-term: 10 mg/L
HEALTH EFFECTS SUMMARY
Acute: May cause nausea, vomiting, headaches, and
irritation of the eyes and respiratory tract.
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 10
mg/L.
Chronic: p-DCB has the potential to cause the
following health effects from long-term exposures at
levels above the MCL: anemia, skin lesions, appetite
loss, yellow atrophy of the liver and adverse blood
effects.
Cancer: There is some evidence that p-DCB has the
potential to cause cancer from a lifetime exposure at
levels above the MCL.
USAGE PATTERNS
Available production data on p-DCB shows a decreas-
ing trend down to 15 million Ibs. in 1981. Demand
owever, was at 74 million Ibs in 1986; rose to 77 million
,os. the following year, and was projected to continue
increasing.
p-Dichlorobenzene is used as an insecticidal fumigant
against clothes moths (35-40%); as a deodorant for
garbage and restrooms (35-40%); as an insecticide for
control of fruit borers and ants; may be applied to tobacco
seed beds for blue mold control; for the control of peach
tree borer; and mildew and mold on leather and fabrics.
It is also used as an intermediate in the manufacture of
other organic chemicals such as 2,5-dichloroaniline, and
in plastics, dyes, Pharmaceuticals.
RELEASE PATTERNS
Chemical waste dump leachates and direct manufac-
turing effluents are reported to be the major source of
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
TOTALS (in pounds)
Top Five States*
VW
TX
DE
GA
LA
Water
*
33,675
27,676
1,280
1,870
750
503
Major Industries
Alkalies, chlorine 27,676
Industrial org. chem. 3,076
Agricultural chem. 750
Cyclic crudes, intermed. 600
Land
4,482
0
3,132
200
0
0
0
3,350
0
0
* Water/Land totals only include facilities with releases
greater than a certain amount - usually 1000 to 10,000 Ibs.
October 7995
Technical Version
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pollution of the chlorobenzenes (including the dichloro-
benzenes) to Lake Ontario. The major source of p-
dichlorobenzene emission to the atmosphere is volatil-
ization from use in toilet bowl deodorants, garbage de-
odorants and moth flakes.
In 1972, 70-90% of the annual USA production of p-
dichlorobenzene was estimated to have been released
into the atmosphere primarily as a result of use in toilet
bowl and garbage deodorants and use in moth control as
a fumigant.
In 1984 it was reported that 67% of the p-dichloroben-
zene consumed in the USA is used for space deodorants
and moth control with 33% used as an intermediate for
polyphenylene sulfide resin production; volatilization from
the deodorants and moth flakes will therefore be the
major emission source to the atmosphere.
From 1987 to 1993, according to the Toxic Release
Inventory, p-DCB releases to water totalled almost 34,000
Ibs. Releases to, land totalled nearly 4,500 Ibs. These
releases were primarily from a single chemical manufac-
turing plant in West Virginia.
benzene in rain-water suggests that atmospheric wash-
out is possible.
For the most part, experimental BCF values reported
in the literature are less than 1000 which suggests that
significant bioconcentration will not occur; however, a
BCF of 1800 was determined for guppies in one study.
General population exposure to p-dichlorobenzene
may occur through oral consumption of contaminated
drinking water and food (particularly fish) and through
inhalation of contaminated air.
ENVIRONMENTAL FATE
If released to soil, p-dichlorobenzene can be moder-
ately to tightly adsorbed. Leaching from hazardous waste
disposal areas has occurred and the detection of p-
dichlorobenzene in various groundwaters indicates that
leaching can occur. Volatilization from soil surfaces may
be an important transport mechanism. It is possible that
p-dichlorobenzene will be slowly biodegraded in soil
under aerobic conditions. Chemical transformation by
hydrolysis, oxidation or direct photolysis are not ex-
pected to occur in soil.
If released to water, volatilization may be the dominant
removal process. The volatilization half-life from a model
river one meter deep flowing one meter/sec with a wind
velocity of 3 m/sec is estimated to be 4.3 hours at 20 deg
C. Adsorption to sediment will be a major environmental
fate process based upon extensive monitoring data in the
Great Lakes area and Koc values based upon monitoring
samples. Analysis of Lake Ontario sediment cores has
indicated the presence and persistence of p-dichloro-
benzene since before 1940. Adsorption to sediment will
attenuate volatilization. Aerobic biodegradation in water
may be possible, however, anaerobic biodegradation is
not expected to occur.
Aquatic hydrolysis, oxidation and direct photolysis are
not expected to be important. If released to air, p-dichlo-
robenzene will exist predominantly in the vapor-phase
and will react with photochemically produced hydroxyl
radicals at an estimated half-life rate of 31 days in typical
atmosphere. Direct photolysis in the troposphere is not
expected to be important. The detection of p-dichloro-
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
* 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
Page 2
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