| Chemical Abstract Number (CAS #) |
11097691
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| Synonyms | PCB-1254 |
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Aroclor 1254 |
| 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 hydraulic fluid, rubber plasticizers, synthetic resin plasticizers, adhesives,
wax extenders, dedusting agents, inks, cutting oils, pesticide extenders, sealants and caulking
compounds
In routine screening program for in vitro assays, S-9 fractions are generally prepared from the
livers of male rats which have been treated with nonspecific enzyme inducers such as
phenobarbital or Arochlor 1254.
Although the production and sales was discontinued in late 1977, it is still present in
transformers now in use.
In electrical capacitors, electrical transformers, vacuum pumps and gas-transmission turbines.
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| Apparent Color | Light yellow, viscous liquid
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| Odor | PRACTICALLY ODORLESS
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| Boiling Point | Distillation range 365-390 deg C
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| Molecular Weight | Average mol wt: 327
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| Density | 1.495-1.505 at 65 deg C/15.5 deg C.
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| Sensitivity Data | Irritating to skin and eyes.
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| Environmental Impact | Current evidence suggests that the major source of Aroclor 1254 release to the
environment is an environmental cycling process of Aroclor 1254 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 1254, are also currently released to the environment from
landfills contaning PCB waste materials and products, incineration of municipal refuse and sewage
sludge, and improper (or illegal) disposal of PCB materials, such as waste transformer fluid, to
open areas. Aroclor 1254 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 1254 is generally resistant to
biodegradation. Although biodegradation of Aroclor 1254 may occur slowly in the environmental,
no other degradation mechanism 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 1254 will become tightly adsorbed to the soil particles.
In the presence of organic solvents, PCBs may have a tendency to leach through soil. Although
the volatilization rate of Aroclor 1254 may be low from soil surfaces, the total loss by
volatilizaiton over time may be significant because of the persistence and stability of Aroclor
1254. 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 1254 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 1254
volatilizes relatively rapidly from water. However, strong PCB adsorption competes with
volatilization which may have a half-life in excess of 4 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 1254. Aroclor 1254 has been shown
to bioconcentrate significantly in aquatic organisms. If released to the atmosphere, the PCB
congeners in Aroclor 1254 will primarily exist 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 for 3.1 months to 1.3 years.
Physical removal of Aroclor 1254 from the atmosphere, which is very important environmentally
due to the chemical stability of Aroclor 1254, is accomplished by wet and dry deposition. The
major Aroclor 1254 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 1254, 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 the degree of chlorination. Screening tests have shown that Aroclor 1254 is
generally resistant to biodegradation. Although biodegradation of Aroclor 1254 may occur slowly
in the environment basis, 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 1254 will be tightly adsorbed in
soil with adsorption generally increasing as the degree of chlorination of the individual congeners
increase. Aroclor 1254 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 1254 may be low from soil surfaces due to the tight adsorption, the
total loss by volatilization over time may be both significant and the major loss process, due to the
persistence and chemical stability of Aroclor 1254.
AQUATIC FATE: PCBs, such as Aroclor 1254, are mixtures of different congeners of
chlorobiphenyls and the relative importance of the environmental fate mechanisms generally
depends on the degree of chlorination . In general, the persistence of PCBs increases with the
degree of chlorination. Screening tests have shown that Aroclor 1254 is generally resistant to
biodegradation. It has also been shown that the higher chlorinated congeners in PCBs are
susceptible to reductive dechlorination by anaerobic microorganisms found in aquatic
sediments . Although biodegradation of higher chlorinated congeners may occur very 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 1254(1,3). The PCBs with the highest vapor pressures (low Cl) will be enriched in air.
The lower chlorinated congeners of Aroclor 1254 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 1254 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 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). Strong PCB adsorption to sediment significantly decreases the rate of
volatilization; the volatilization half-life of Aroclor 1254 from typical bodies of water has been
estimated to be in excess of 4 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
processes with respect of Aroclor 1254. Aroclor 1254 has been shown to bioconcentrate
significantly in aquatic organisms.
ATMOSPHERIC FATE: The vapor pressures of the PCB congeners present in Aroclor 1254
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(1,2,3). In one experiment,
2.1% of the Aroclor 1254 present in an air sample at 20 deg C was found to be associated with
the particulate-phase while 25% was associated with the particulate-phase at 0 deg C . Physical
removal of PCBs 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 detection of Aroclor 1254 in various rainwaters is an indication of the importance of wet
deposition. The vapor-phase reaction of Aroclor 1254 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 major PCB congeners present in Aroclor 1254
has been estimated to range from 3.1 months to 1.3 years with the half-life increasing as the
degree of chlorination increases. The relatively long degradation half-lives in air indicate that
physical removal is more important than chemical transformation.
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| Drinking Water Impact | DRINKING WATER: Aroclor 1254 levels ranging from not detectable to 36 ng/L were
found in a reservoir serving Fort Edward, NY near the Hudson River .
GROUNDWATER: Aroclor 1254 was detected in 30 of 1040 groundwater samples from NJ,
with the highest detected concentration being 0.4 ppb .
SURFACE WATER: Aroclor 1254 was detected in 88 of 612 surface water samples from NJ,
with the highest detected concentration being 127 ppb . An assessment of the USEPA
STORET Database found Aroclor 1254 detected in 9.0% of 1186 observation stations .
Aroclor 1254 has been positively detected in Lakes Ontario, Erie, Huron, Michigan and
Superior . A mean Aroclor 1254 concn of 0.3 ppb was found in the Black Creek in Indiana
during 1977-8 .
RAIN/SNOW: A review of Aroclor 1254 levels found in rain and snow from the United States
has reported levels of <1-49 ng/L in rain and 24-76 ng/L in snow . 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 1254 detected in 1.8%
of 714 observation stations . The concentration of Aroclor 1254 found in the leachate from a
hazardous waste landfill was 70 ppb .
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