| Chemical Abstract Number (CAS #) |
11104282
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| Synonyms | PCB-1221 |
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Aroclor 1221 |
| Analytical Methods |
EPA Method 505 |
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EPA Method 508 |
EPA Method 608 |
EPA Method 617 |
EPA Method 625 |
EPA Method 8080A |
EPA Method 8081 |
EPA Method 8250A |
| Molecular Formula | UVCB |
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| Use | Formerly used in gas-transmission turbine hydraulics, rubber plasticizers, adhesives, and
electrical capacitors.
Although the production and sale was discontinued in late 1977, it is still present in many of the
capacitors now in use.
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| Apparent Color | Colorless mobile oil.
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| Odor | PRACTICALLY ODORLESS
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| Melting Point | 1 DEG C
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| Molecular Weight | Average mol wt: 192
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| Density | 1.182-1.192/15.5 deg C
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| Sensitivity Data | Irritating to skin and eyes.
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| Environmental Impact | PCBs such as Aroclor 1221, are currently released to the environment from landfills
containing PCB waste material and products, by incineration of municipal refuse and sewage
sludge, by improper (or illegal) disposal of PCB materials (such as waste transformer fluid) to
open areas and by an environmental cycling process of PCBs previously introduced into the
environment. Aroclor 1221 is a mixture of different congeners of chlorobiphenyl and the relative
importance of the environmental fate mechanisms generally depends on the degree of chlorination.
In general, the persistence of the PCB congeners increase with an increase in the degree of
chlorination. In contrast to the more highly chlorinated Aroclors, Aroclor 1221 appears to be
reasonably degradable on an environmental basis. Screening studies have shown that Aroclor
1221 is readily biodegradable. Biodegradation is probably the ultimate degradation process in
both natural water and soil systems since other degradation processes do not appear to be
important. The PCB composition of the biodegraded Aroclor is different from the original
Aroclor. If released to soil, the PCB congeners present in Aroclor 1221 will become tightly
adsorbed to the soil particles. In the presence of organic solvents PCBs may have a tendency to
leach through soil. Significant volatilization of Aroclor 1221 may occur from soil surfaces.
Enrichment of the low Cl PCBs occurs in the vapor phase relative to the original Aroclor; the
residue will be enriched in the PCBs containing high Cl content. If released to water, adsorption
to sediment and suspended matter will be an important fate process. Although adsorption may
immobilize Aroclor 1221 for relatively long periods of time eventual resolution into the waste
column has been shown to occur. The PCB composition in water will be enriched tin 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, Aroclor 1221 volatilizates
relatively rapidly from water. However, strong PCB adsorption to sediment significantly competes
with volatilization which may have a half-life ranging from 2 months to 1 year in typical bodies of
water. The PCB congeners present in Aroclor 1221 have been shown to bioconcentrate
significantly in aquatic organisms. If released to the atmosphere, the PCB congeners in Aroclor
1221 will exist primarily in the vapor-phase with enrichment of the most volatile PCBs. The
dominant atmospheric transformation process for these congeners is probably the vapor-phase
reaction with hydroxyl radicals which has estimated half-lives ranging from 12.9 to 27.8 days.
Physlical removal of Aroclor 1221 frohm the d dry deposition, although wet deposition will be
more important then dry deposition. The major Aroclor 1221 exposure routes to humans are
through food and drinking water, and by inhalation of contaminated air. Dermal exposure is
important for workers involved with handling PCB-containing electrical equipment, spills or
waste-site materials and for swimmers in polluted water.
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| Environmental Fate | TERRESTRIAL FATE: PCBs, such as Aroclor 1221, are mixtures of different
congeners of chlorobiphenyl and the relative importance of the environmental fate mechanisms
generally depends on the degree of chlorination . In general, the persistence of PCB congeners
increases with an increase in the degree of chlorination. Screening tests have shown that Aroclor
1221 is readily biodegradable. Since no other degradation mechanisms have been shown to be
important in soil systems, biodegradation may be the ultimate degradation process in soil.
Experimentally determined Koc values have shown that the PCB congeners present in Aroclor
1221 will be tightly adsorbed in soil with adsorption generally increasing as the degree of
chlorination of the individual congeners increase although the most water soluble PCBs will be
leached preferentially. Aroclor 1221 should not leach significantly in most aqueous soil systems.
In the presence of organic solvents, which may be possible at waste sites, PCBs may have a
tendency to leach through soil. Soil volatilization data for the Aroclors more highly chlorinated
than Aroclor 1221 indicate that significant volatilization of Aroclor 1221 may occur from soil
surfaces(2,SRC).
AQUATIC FATE: PCBs, such as Aroclor 1221, are mixtures of different congeners of
chlorobiphenyl and the relative importance of the environmental fate mechanism generally
depends on the degree of chlorination . In general, the persistence of PCBs increases with an
increase in the degree of chlorination. Screening tests have shown that Aroclor 1221 is
biodegraded relatively rapidly. It has also been shown that the chlorinated congeners in PCBs are
susceptible to reductive dechlorination by anaerobic microorganisms found in aquatic
sediments . Since no other degradation processes have been shown to be important in
environmental aquatic systems, biodegradation is probably the ultimate degradation mechanism in
natural water. In water, adsorption to sediments and organic matter is a major fate process of
Aroclor 1221(1,3). The most water soluble PCBs will be enriched in water relative to the
sediment, and the leached sediment will be enriched in the higher chlorinated PCBs (lowest
solubilities in water). The lower chlorinated congeners of Aroclor 1221 will sorb less strongly
than the higher chlorinated congeners, but tight adsorption should occur for all congeners.
Although adsorption can immobilize PCBs for relatively long periods of time in the aquatic
environment, resolution into the water column has been shown to occur on an environmental
level. Volatilization of dissolved Aroclor 1221 is an important aquatic process. A study conducted
on Lake Michigan has indicated that volatilization may be the major removal mechanism of total
PCBs from lakes . The PCBs with the highest vapor pressures (low Cl) will be enriched in the
air. Strong PCB adsorption to sediment significantly decreases the rate of volatilization; the
volatilization half-life of Aroclor 1221 from typical bodies of water has been estimated to range
from 2 months to 1 year when the effects of adsorption are considered. Aquatic hydrolysis and
oxidation are not important processes with respect to Aroclor 1221. Aroclor 1221 has been
shown to bioconcentrate significantly in aquatic organisms.
ATMOSPHERIC FATE: The vapor pressures of the PCB congeners present in Aroclor 1221
indicate that they will exist primarily in the vapor phase in the ambient atmosphere with
enrichment of PCBs with the highest vapor pressures (low Cl) and with only minor partitioning to
the particulate-phase(1,2). Physical removal of PCB's in the atmosphere is accomplished by wet
and dry deposition processes ; dry deposition will be important only for the PCB congeners
associated with the particulate-phase. The vapor-phase reaction of Aroclor 1221 with hydroxyl
radicals which are photochemically formed by sunlight, may be the dominant degradation process
in the atmosphere. The estimated half-life for this reaction with the dominant PCB congeners
present in Aroclor 1221 has been estimated to range from 12.9 to 27.8 days with the half-life
increasing as the degree of chlorination increases.
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| Drinking Water Impact | DRINKING WATER: PCB congeners of Aroclor 1221 have been detected in tap water
from Fort Edward, NY which is located near a heavily polluted section of the Hudson River .
Raw tap water in Waterford, NY treatment plant has PCB levels 0.05-0.24 ppb .
SURFACE WATER: An assessment of the USEPA STORET Database found Aroclor 1221
detected in 0.09% of 974 observation stations . PCB congeners of Aroclor 1221 have been
found at levels of 0.5-145 ng/L at various locations in the Hudson River during July and August
1983 . Aroclor 1221 has been detected in river water from the Nile River in Egypt .
RAIN/SNOW: Levels up to 158 ug/L (1975-78) found in Canada, USA and Europe with levels
decreasing to 1986 (PCBs) .
In raw tap water in the Waterford, NY treatment plant, which also has the Hudson River as its
source, mean PCB levels in 1976 were 0.12 ug/l (range: 0.05-0.24). Polychlorinated Biphenyls/
EFFL: An assessment of the USEPA STORET Database found Aroclor 1221 detected in 1.1%
of 703 observation stations . Aroclor 1221, in combination with Aroclors 1242 and 1254, was
detected at a mean concn of 20 ppb in 14 of 24 raw wastewaters collected from the aluminum
forming industries .
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