United States
Environmental Protection
Agency
Office of Water
4601
EPA 811-F-95-003aa-T
October 1995
National Primary Drinking
Water Regulations
Polychlorinated Biphenyls (PQBs)
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 1336-36-3
COLOR/ FORM/ODOR: PCB is generic term
for group of organic chemicals which
can be odorless or mildly aromatic
solids or oily liquids; available in
mixtures containing several PCBs and
other organics as well.
M.P.: 340 to 375° C B.P.: N/A
OCTANOL/WATER PARTITION (Kow): N/A
VAPOR PRESSURE: N/A; moderately volatile
from water and soil
DENSITY/SPEC. GRAV.:- 1.44 at 30° C
SOLUBILITY: N/A; insoluble in water
SOIL SORPTION COEFFICIENT:
Koc generally above 5000; low
mobility in soil, but may leach with
mobile organic solvents.
ODOR/TASTE THRESHOLDS: N/A
BlOCONCENTRATION FACTOR:
Log BCF - 3.26 to 5.27 in aquatic
organisms; expected to bioconcentrate
in aquatic organisms.
HENRY'S LAW'COEFFICIENT:
3.3x10-4 to 5x10-5 atm-cu m/mole at 20
degC
TRADE NAMES/SYNONYMS:
PCB, Chlorinated diphenyl, Clophen,
Kanechlor, Aroclor, Fenclor, Chlorextol,
Dykanol, Inerteen, Monter, Pyralene,
Santotherm, sovol, Therminol, Noflamol
DRINKING WATER STANDARDS
MCLG: .zero mg/L
MCL: 0.0005 mg/L
HAL(child): none
HEALTH EFFECTS SUMMARY
Acute: EPA has found PCBs to potentially cause the
following health effects from short-term exposures at
levels above the MCL: acne-like eruptions and pigmen-
tation of the skin; hearing and vision problems; spasms.
Chronic: PCBs have the potential to cause the
following health effects from long-term exposure at levels
above the MCL: effects similar to acute poisonings;
irritation of nose; throat and gastrointestinal tracts;
changes in liver function.
Cancer: There is some evidence that PCBs may have
the potential to cause cancer from a lifetime exposure at
levels above the MCL.
USAGE PATTERNS
Production of PCBs has decreased drastically: from
over 86 million Ibs. in 1970 to 35 million Ibs in 1977. EPA
banned most uses of PCBs in 1979. In 1975 it was
estimated that industries consumed PCBs as follows:
capacitors, 70%; Transformers, 30%
PCBs were formerly used in the USA as hydraulic
fluids, plasticizers, adhesives, fire retardants, way ex-
tenders, dedusting agents, pesticide extenders, inks,
lubricants, cutting oils, in heat transfer systems, carbon-
less reproducing paper.
RELEASE PATTERNS
Current evidence suggests that the major source of
PCB release to the environment is an environmental
cycling process of PCBs previously introduced into the
environment; this cycling process involves volatilization
from ground surfaces (water, soil) into the atmosphere
with subsequent removal from the atmosphere via wet/
dry deposition and then revolatilization. PCBs are also
currently released to the environment from landfills con-
taining PCB waste materials and products, incineration
of municipal refuse and sewage sludge, and improper (or
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
Water
TOTALS (in pounds) 784
Top Five States
CA 0
NJ 0
KY 250
WA 0
TN 255
Major Industries
Non-ferrous wire 0
Steel pipe/tubing 0
Pulp mills 0
Land
73,632
58,178
13,188
750
998
251
58,178
13,183
998
October 1995
Technical Version
Printed on Recycled Paper
-------
illegal) disposal of PCB materials, such as waste trans-
former fluid, to open areas.
From 1987 to 1993, according to EPA's Toxic Chemi-
cal Release Inventory, PCB releases to land and water
totalled over 74,000 Ibs., of which about 99 percent was
to land. The bulk of these releases occurred in 1990 and
were primarily from non-ferrous wire drawing and insulat-
ing industries. The largest releases (10% or more of the
total) occurred in California.
ENVIRONMENTAL FATE
PCBs are mixtures of different congeners of
chlorobiphenyl and the relative importance of the envi-
ronmental fate mechanisms generally depends on the
degree of chlorination. In general, the persistence of
PCBs increases with an increase in the degree of chlori-
nation. Mono-, di- and trichlorinated biphenyls biode-
grade relatively rapidly, tetrachlorinated biphenyls biode-
grade slowly, and higher chlorinated biphenyls are resis-
tantto biodegradation. Although biodegradation of higher
chlorinated congeners may occur very slowly on an
environmental basis, no other degradation mechanisms
have been shown to be important in natural water and soil
systems; therefore, biodegradation may be the ultimate
degradation process in water and soil.
If released to soil, PCBs experience tight adsorption
with adsorption generally increasing with the degree of
chlorination of the PCB. PCBs will generally not leach
significantly in aqueous soil systems; the higher chlori-
nated congeners will have a lower tendency to leach than
the lower chlorinated congeners. In the presence of
organic solvents PCBs may leach quite rapidly through
soil. Vapor loss of PCBs from soil surfaces appears to be
an important fate mechanism with the rate of volatilization
decreasing with increasing chlorination. Although the
volatilization rate may be low, the total loss by volatiliza-
tion over time may be significant because of the persis-
tence and stability of PCBs. Enrichment of the low-CI
PCBs occurs in the vapor phase relative to the original
Aroclor; the residue will be enriched in the PCBs contain-
ing high Cl content.
If released to water, adsorption to sediment and sus-
pended matter will be an important fate process; PCB
concentrations in sediment and suspended matter have
been shown to be greater than in the associated water
column. Although adsorption can immobilize PCBs (es-
pecially the higher chlorinated congeners) for relatively
long periods of time, eventual resolution into the water
column has been shown to occur. The PCB composition
in the water will be enriched in the lower chlorinated PCBs
because of their greater water solubility, and the least
water soluble PCBs (highest Cl content) will remain
adsorbed. In the absence of adsorption, PCBs volatilize
relatively rapidly from water. However, strong PCB ad-
sorption to sediment significantly competes with volatil-
ization, with the higher chlorinated PCBs having longer
half-lives than the lower chlorinated PCBs. Although the
resulting volatilization rate may be low, the total loss by
volatilization overtime may be significant because of the
persistence and stability of the PCBs.
If released to the atmosphere, PCBs will primarily exi4
in the vapor-phase; the tendency to become associated
with the particulate-phase will increase as the degree of
chlorination of the PCB increases. The dominant atmo-
spheric transformation process is probably the vapor-
phase reaction with hydroxyl radicals which has esti-
mated half-lives ranging from 12.9 days for
monochlorobiphenyl to 1.31 years for
heptachlorobiphenyl. Physical removal of PCBs from the
atmosphere, which is very important environmentally, is
accomplished by wet and dry deposition.
PCBs have been shown to bioconcentrate significantly
in aquatic organisms. Average log BCFs of 3.26 to 5.27,
reported for various congeners in aquatic organisms,
show increasing accumulation with the more highly chlo-
rinated congeners. The major PCB exposure routes to
humans are through food and drinking water, and by
inhalation of contaminated air. .
OTHER REGULATORY INFORMATION
MONITORING:
. FOR GROUND/SURFACE WATER SOURCES:
INITIAL FREQUENCY- 4 quarterly samples every 3 years
REPEAT FREQUENCY- If no detections during initial round:
2 quarterly per year if serving >3300 persons;
1 sample per 3 years for smaller systems
TRIGGERS - Return to Initial Freq. if detect at congener-specific limits
ANALYSIS:
REFERENCE SOURCE METHOD NUMBERS
EPA 600/4-88-039 505; 508; 508A
TREATMENT:
BEST AVAILABLE TECHNOLOGIES
Granular Activated Charcoal,
FOR ADDITIONAL INFORMATION:
* EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
* Other sources of lexicological 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
------- |