| Chemical Abstract Number (CAS #) |
53469219
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| Synonyms | PCB-1242 |
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Aroclor 1242 |
| 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 | Used in electrical capacitors, electrical transformers, vacuum pumps, and gas-transmission
turbines.
Formerly used as heat transfer fluid, hydraulic fluids, rubber plasticizer, and in carbonless paper,
adhesives and wax extenders.
Although the production and sale was discontinued in late 1977, it is still present in transformers
and capacitors now in use.
Formerly used in electrical transformers, gas transmission turbines, hydraulic fluids, adhesives,
plasticizer rubber, heat transfer systems, wax extenders and carbonless reproducing paper.
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| Apparent Color | Colorless mobile oil.
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| Boiling Point | 325-366 deg C
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| Molecular Weight | Average mol wt: 261
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| Density | 1.381-1.392 at 25 deg C/15.5 deg C
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| Sensitivity Data | Irritating to skin and eyes. Polychlorinated biphenyls
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| Environmental Impact | Current evidence suggests that the major source of Aroclor 1242 release to the
environment may be an environmental cycling process of Aroclor 1242 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, such as Aroclor 1242, are also currently released to the environment
from landfills containing PCB waste materials and products, incineration of municipal refuse and
sewage sludge, and improper (or illegal) diposal of PCB materials, such as waste transformer
fluid, to open areas. Aroclor 1242 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. Screening studies have shown that Aroclor 1242 is biodegraded slowly.
Although biodegradation of Aroclor 1242 may occur slowly in the environment, 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. The PCB
composition of the biodegraded Aroclor is different from the original Aroclor. If released to soil,
the PCB congeners present in Aroclor 1242 will become tightly adsorbed to the soil particles.
Although the volatilization rate of Aroclor 1242 may be low from soil surfaces, the total loss by
volatilization over time may be significant because of the persistence and stability of Aroclor
1242. 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 can immobilize Aroclor 1242 for relatively long periods of time, eventual resolution
into the water column has been shown to occur. The PCB composition in 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, Aroclor 1242
volatilizes relatively rapidly from water. However, strong PCB adsorption to sediment
significantly competes with volatilization which may have a half-life of 2-7 years in typical bodies
of water. Although the resulting volatilization rate may be low, the total loss by volatilization over
time may be significant because of the persistence and stability of Aroclor 1242. Aroclor 1242 has
been shown to bioconcentrate significantly in aquatic organisms. If released to the atmosphere,
the PCB congeners in Aroclor 1242 will exist primarily in the vapor-phase with enrichment of the
most volatile PCBs although a relatively small percentage will partition to the particulate phase.
The dominant atmospheric transformation process for these congeners is probably the
vapor-phase reaction with hydroxyl radicals which has estimated half-lives ranging from 27.8 days
to 4.75 months. Physical removal of Aroclor 1242 from the atmosphere, which is important
environmentally due to the chemical stability of Aroclor 1242, is accomplished by wet and dry
deposition. The major Aroclor 1242 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. Exposure through consumption of contaminated fish may be
especially important.
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| Environmental Fate | TERRESTRIAL FATE: PCBs, such as Aroclor 1242, 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
1242 is biodegraded slowly. Although biodegradation of Aroclor 1242 may occur slowly in the
evironment, no other degradation mechanisms have been shown to be important in soil systems;
therefore, biodegradation may be the ultimate degradation process in soil. Experimentally
determined Koc values have shown that Aroclor 1242 will be tightly adsorbed in soil with
adsorption generally increasing as the degree of chlorination of the individual congeners increase.
Aroclor 1242 should not leach significantly in most aqueous soil systems although the most water
soluble PCBs will be leached preferentially. In the presence of organic solvents, which may be
possible at waste sites, PCBs may have a tendency to leach through soil. Although the
volatilization rate of Aroclor 1242 may not be rapid from soil surfaces due to the tight adsorption,
the total loss by volatilization over time may be significant because of the persistence and stability
of Aroclor 1242.
AQUATIC FATE: PCBs, such as Aroclor 1242, 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 PCBs increases with an
increase in the degree of chlorination. Screening tests have been shown that Aroclor 1242 is
biodegraded slowly. It is also been shown that the more highly chlorinated congeners in PCBs are
susceptible to reductive dechlorination by anaerobic microorganisms found in aquatic
sediments . Although biodegradation of Aroclor 1242 may occur slowly in the environment, no
other degradation mechanisms have been shown to be important in environmental aquatic
systems; therefore, biodegradation may be the ultimate degradation process in natural water. In
water, adsorption to sediments and organic matter is a major fate process for Aroclor 1242(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 1242 will sorb less strongly than the higher chlorinated
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 suggesting that the substantial quantities of PCBs contained in aquatic
sediments can act as an environmental sink for environmental redistribution of PCBs(4,5).
Volatilization of dissolved Aroclor 1242 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 (lowest number of Cl's) will be
enriched in the air. Strong PCB adsorption to sediment significantly decreases the rate of
volatilization; the volatilization half-life of Aroclor 1242 from typical bodies of water has been
estimated to be 2-7 years when the effects of adsorption are considered. Although the
volatilization rate may be low, the total loss by volatilization over time may be significant because
of the persistence and stability of the PCBs. Aquatic hydrolysis and oxidation are not important
processess with respect to Aroclor 1242. Aroclor 1242 has been shown to bioconcentrate
significantly in aquatic organisms.
ATMOSPHERIC FATE: The vapor pressures of the PCB congeners present in Aroclor 1242
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) although a relatively small
percentage can be expected to partition to atmospheric particulates(1,2). Physical removal of
PCBs in the atmosphere is accomplished by wet and dry deposition processess ; dry deposition
will be important only for the PCB congeners associated in the particulate phase. The detection of
Aroclor 1242 in various rainwaters is an indication of the importance of wet deposition. The
vapor-phase reaction of Aroclor 1242 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 1242 has been estimated to
range from 28 days to 4.8 months with the half-life increasing as the degree of chlorination
increases. The relatively long degradation half-lives in air indicates that physical removal may be
more important than chemical transformation.
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| Drinking Water Impact | GROUNDWATER: Aroclor 1242 was detected in 70 of 662 groundwater samples from
NJ, with the highest detected concentration being 3.4 ppb .
SURFACE WATER: Aroclor 1242 was detected in 46 of 612 surface water samples from NJ,
with the highest detected concentration being 117.3 ppb . An assessment of the USEPA
STORET Database found Aroclor 1260 detected in 4.0% of 1174 observation stations .
Aroclor 1242 has been detected in Lakes Ontario, Erie, Huron, Michigan and Superior . Mean
Aroclor 1242 levels of 0.64, 1.48 and 0.50 ng/l were detected in the water column of Lake
Superior in 1978, 1979, and 1980, respectively . PCB congeners of Aroclor 1242 were detected
at three locations of the Hudson River in 1983 at levels ranging from below 1 ng/l to 150 ng/l .
RAIN/SNOW: Aroclor 1242 levels of 16 to 57 ng/l were detected in rainwater and 33-41 ng/l in
snow collected from urban and rural areas of Lake Michigan between 1975-77 . Levels up to
158 ng/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 1242 detected in 1.9%
of 720 observation stations . The average Aroclor 1242 concn emitted from gas vents at a
hazardous waste landfill in NC was found to be 123 ug/cu m . The concentration of Aroclors
1242 and 1016 found in the leachate from a hazardous waste landfill was 0.11-1.9 ppm . The
concn of Aroclor 1242, in combination with Aroclors 1016 and 1254, was found to range from
110 ug/L to 1.8 g/L in leachate form the Kin-Buc I landfill in NJ . Monitoring of the
wastewater effluent from the Los Angeles County wastewater treatment plant between 1980-1
found Aroclor 1242 levels of 0.94 ug/L .
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