United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/004 Apr. 1987
v>EPA Project Summary
Characterization of PCB
Transformer/Capacitor Fluids
and Correlation with PCDDs
and PCDFs in Soot
Beverly Campbell and Anthony Lee
Dielectric fluids in transformers and
capacitors often contain polychlori-
nated biphenyls (PCBs) or chloroben-
zenes. These substances may generate
polychlorinated dibenzofurans (PCDFs)
and polychlorinated dibenzo-p-dioxins
(PCDDs) under certain conditions of
combustion/pyrolysis. When electrical
equipment containing these fluids is in-
volved in an accidental fire, the result-
ing smoke, soot, and residues may be
contaminated with PCDDs, PCDFs, and
other chlorinated hydrocarbons.
The full report contains a review of
several laboratory studies investigating
the sources of PCDDs and PCDFs as
well as the conditions under which they
are formed. In addition, some data from
sites of actual fire incidents are avail-
able and are discussed. Chloroben-
zenes and PCBs do not form PCDDs and
PCDFs when heated in the absence of
oxygen. During fires, the dielectric fluid
of transformers or capacitors may be
leaked or vented from ruptured cas-
ings. With exposure to oxygen, PCBs
can produce PCDFs and chloro-
benzenes can produce PCDDs. The par-
ticular isomers of PCDDs and PCDFs
formed are related to the number of
chlorine substituents in the reacting
material.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
In August 1982, the U.S. Environmen-
tal Protection Agency (EPA) decided to
permit the continued use of electrical
transformers containing polychlori-
nated biphenyls (PCBs) based on the re-
ported low frequency of leaks and spills
of PCBs from this equipment relative to
the high costs of replacing or securing
these transformers. Under Section
6(e)(2)(B) of the Toxic Substances Con-
trol Act (TSCA), EPA can authorize a use
of PCBs provided that the use "will not
present an unreasonable risk of injury to
health or the environment." EPA deter-
mined that the continued use of PCBs-
contaminated transformers (50-500
ppm PCBs) and non-PCB transformers
(<50 ppm PCBs) did not present unrea-
sonable risks to public health.
A closer evaluation of the fire-related
risks posed by the continued use of PCB
transformers, and the costs and bene-
fits of actions designed to reduce those
risks followed the 1982 determination.
EPA issued a Proposed Rule on October
11,1984, concerning PCB transformers.
EPA determined that fires involving
transformers containing >500 ppm
PCBs present risks to human health and
the environment. The extreme toxicity
of materials which can be formed dur-
ing fires involving PCB transformers,
and the potential for human and envi-
ronmental exposures to these com-
pounds, contributed to EPA's proposed
rule.
Considering the extensive comments
received during the public comment pe-
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riod for the Proposed Rule, EPA modi-
fied the Final Rule concerning:
• Evaluation of the use of PCB trans-
formers in or near industrial build-
ings separately from the use of PCB
transformers in or near commercial
buildings.
• Relative probabilities of failures
and fires in different types of PCB
transformers installations, placing
more stringent controls on those
transformers that EPA believes
pose higher risks of failures and
fires.
• Increased emphasis on the preven-
tion of PCB transformer fires
through increased electrical protec-
tion, and decreased emphasis on
the use of isolation measures to
minimize the spread of already
formed and/or released contami-
nants.
On July 9,1985, EPA promulgated its
Final Rule on PCBs in electrical trans-
formers, the culmination of a long fact-
finding and rule-making process that
began shortly after the transformer fire
at the State Office Building in Bingham-
ton, NY, February 5, 1981.
Summary and Conclusions
An estimated 74,000 tons of PCBs are
still in use in U.S. transformers and ca-
pacitors. On July 9, 1985, the EPA pro-
mulgated its Final Rule on PCBs in elec-
trical transformers. This rule specifies
that PCBs at any concentration may be
used in transformers (other than in rail-
road locomotives and self-propelled
railroad cars) subject to the following
conditions:
1} the use of higher secondary volt-
age (>480 volts) network PCB
transformers in or near commer-
cial buildings after October 1,
1990, is prohibited.
2) the installation of enhanced elec-
trical protection on lower second-
ary voltage network PCB trans-
formers and higher secondary
voltage radial PCB transformers in
use in or near commercial build-
ings is required by October 1,
1990.
3) further installation of PCB trans-
formers in or near commercial
buildings is prohibited after Octo-
ber 1, 1985.
4) the registration of all PCB trans-
formers with fire-response person-
nel and building owners is re-
quired by December 1, 1985.
5) the markings of the exterior of all
PCB transformer locations is re-
quired by December 1, 1985.
6) the removal of stored combusti-
bles located near PCB transform-
ers is required by December 1,
1985.
There are still many uncertainties of
the scope and nature of the hazards
created in PCB transformer and capaci-
tor fires. One potential hazard is the
generation of highly toxic substances
such as PCDDs and PCDFs from the
pyrolysis of PCBs and chlorobenzenes.
This report identifies 30 fire incidents
involving PCB transformers and capaci-
tors in the United States and western
Europe that occurred from September
1978 through February 1985. The fol-
lowing questions are addressed in this
study:
• Are PCDDs and PCDFs formed in
PCB transformers under normal op-
erating conditions?
• How are the constituents of the
transformer fluids related to the
type and amount of PCDDs and
PCDFs formed?
• What are the temperature and
other reaction conditions that favor
the formation of the PCB combus-
tion products?
The July 9, 1985 rule provides for a
gradual phaseout of some PCB trans-
formers while recognizing the potential
for additional fire accidents in the in-
terim. Moreover, PCB capacitors are not
covered under the July 9,1985 rule and,
since they have also been involved in
fire incidents, capacitors are potential
release sources for PCBs and combus-
tion by-products into the environment.
The full report presents and evaluates
the available literature and published
data on analyses of transformer fluids
and soot generated in fires. Even
though there have been at least 30 re-
ported incidents, a wide variety of prob-
lems that hinder the analysis and evalu-
ation of the data remain, including:
• Limitation of Analytical Data. Very
few analytical data have been gen-
erated for each PCB fire incident.
Because of the high cost of isomer
analysis and the large number of
isomers that characterize the PCBs,
PCDFs, and PCDDs, few analyses
are actually performed for any
specific isomer in the aftermath of a
PCB fire incident.
• Differences in Sampling and Ana-
lytical Protocols. Sampling and
analysis protocols for contami-
nants generated in transformer
fires are not yet fully standardized,
and thus a wide variety of sampling
and analytical methodologies are
often employed. Some data are
based on the analysis of soot and
are reported on a weight/weight
basis. Other data are based on the
analysis of wipe samples and re-
ported on a weight/area basis.
Thus, it is very difficult to compare
one fire incident with another, or to
evaluate the significance of the
data in one incident relative to that
of another.
• Lack of Background Data. Very few
background data are available on:
(a) composition of transformer
fluids and, (b) composition and
levels of PCBs, PCDFs, chloroben-
zenes, and PCDDs in the environ-
ment.
Despite these problems, the following
conclusions may be made from analysis
of the data from the literature on PCB
transformer fires:
1) PCDFs and PCDDs are not formed
in transformers containing PCBs
under normal operating condi-
tions. Their formation requires
thermally stressful conditions and
the presence of oxygen.
2) Electrical arcings in transformers
do not lead to the formation of
PCDFs and PCDDs.
3) A temperature zone between
600°C and 680°C may be regarded
as optimal for the formation of
PCDFs.
4) The amount and the specific PCDF
isomers formed are related to the
concentration of and type of PCB
homologs in the transformer fluid.
5) Chlorobenzene diluents in the
transformer fluids are required for
the formation of PCDDs.
The Binghamton, NY transformer fire
accident was the first to capture major
media and scientific attention. In that
fire, both PCDDs and PCDFs were found
in the generated soot, leading to the
concern that these compounds were be-
ing formed in situ in PCB transformers
and capacitors under normal operating
conditions. The available evidence does
not support this concern. Analyses con-
ducted by the Electric Power Research
Institute (EPRI) and EPA of samples of
dielectric fluids taken from in-service
transformers and capacitors and those
involved in fire accidents showed no ap-
preciable difference in PCDF values
from stock material. No PCDDs were de-
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tected. Under normal use conditions, it
does not appear that PCDFs are gener-
ated to any significant extent in the
transformer.
Correspondingly, a second concern
was whether PCDDs and PCDFs are
formed during electrical discharges as-
sociated with transformer performance.
To investigate this issue, experiments
involving the arcing of electrical energy
through various transformer fluids were
performed. There was no appreciable
difference in PCDF levels before and
after electrical arcing. The supposition
is that the level of oxygen is very low in
the transformer and, thus, does not
offer the environment for combustion
resulting in the formation of PCDFs and
PCDDs.
The amount and the specific PCDD
and PCDF isomers formed in a PCB
transformer fire appear to be related to
the concentration of and type of PCB
homologs in the transformer fluids.
This supposition is supported by recent
estimations on the boiling points for
dioxins and furans that indicate that the
boiling temperatures for tri-CDDs and
tri-CDFs and the higher chlorinated
PCDDs and PCDFs range from 375°C to
537°C. A first approximation of the ther-
modynamic conditions would favor the
formation of tri- and higher chlorinated
PCDFs and PCDDs. Combustion studies
conducted by EPA and EPRI also pro-
vide evidence that the concentration of
and type of PCB homologs in the trans-
former fluids are probably related to the
amount and the specific PCDD and
PCDF isomers formed in a PCB trans-
former fire. The EPA study indicated
that the optimal conditions for PCDF for-
mation from PCBs are a temperature
near 675°C and a residence time of 0.8
second or longer. The EPRI study
demonstrated that tetra- and penta-CDF
yields are roughly proportional to PCB
concentrations in the starting material,
but it indicated that significant dibenzo-
furan destruction begins to occur at ap-
proximately 550°C.
A final issue pertains to the question
of the use of diluents in transformer
fluids. Of the 30 reported fire incidents
involving PCB transformers and capaci-
tors, unequivocal evidence of PCDDs
formation was found only in the
Binghamton, NY fire. The Binghamton,
NY transformer contained chloroben-
zenes as a diluent, adding to the evi-
dence that the pyrolysis of chloroben-
zenes leads to the formation of PCDDs.
Such evidence has also been found in
chemical manufacturing processes and
in metal recovery sites involving PCB
transformers. Chlorobenzenes should
be carefully evaluated for use as trans-
former fluids or diluents.
Fire Incidents Involving PCB
Transformers and Capacitors
PCBs have been used extensively as
dielectric fluid in capacitors and trans-
formers since the 1950s. An estimated
74,000 tons of PCBs are still used in U.S.
transformers and capacitors. At least 30
fire incidents involving PCB transform-
ers and capacitors have occurred in the
past 7 years as identified in Table 1.
There are no Federal guidelines to de-
fine acceptable cleanup levels for toxic
releases from PCB transformer and ca-
pacitor fires. Current regulations state,
however, that all spills and leaks of
PCBs or dioxins-contaminated material
should be cleaned up to preexisting
background levels whenever there is a
threat of contamination to water, food,
feed, or humans. NIOSH has detected
background levels in urban areas of up
to 0.5 meg PCBs/100 cm2 of surface
area. Following the occurrence of PCBs-
related fire incidents, several states and
other countries have established con-
tamination cleanup criteria. These crite-
ria are presented in Table 2.
Correlation of Combustion/
Pyrolysis Products Generated
and Constituents of
Transformer Fluids
The ability to predict the type and the
quantity of toxic contaminants that may
form in a PCB transformer/capacitor fire
is of prime importance in the develop-
ment of prevention and control meas-
ures. Because of the scarcity and gener-
ally poor quality of data obtained from
PCB transformer fire incidents, pyrolytic
studies under laboratory-controlled
conditions have been employed.
EPA, through a contract with Midwest
Research Institute, Kansas City, MO,
conducted a study to evaluate thermal
degradation products using a bench-
scale thermal destruction system. The
results indicated that both temperature
and oxygen significantly affected PCDF
yield. Statistical analysis showed a lin-
ear relationship for PCDFs formed ver-
sus the concentration of PCBs.
Table 1. Fire Incidents Involving PCB Transformers or Capacitors Since 1978
Location Date
Norrtalje, Sweden
Cincinnati, Ohio
Binghamton, New York
Stockholm, Sweden
Danviken, Sweden
Boston, Massachusetts
Skovde, Sweden
Miami, Florida
Arvika, Sweden
St. Paul, Minnesota
Imatra, Finland
Helsinki, Finland
Surahammar, Sweden
Hallstahammar, Sweden
Railway Locomotive, Sweden
Kaukopaa, Sweden
Kisa, Sweden
San Francisco, California
Halmstad, Sweden
Chicago, Illinois
Bofors, Sweden
Columbus, Ohio
Sodertalje, Sweden
Finspang, Sweden
Motors, Sweden
Vetlanda, Sweden
Reims, France
Oslo Lysverker, Norway
Sandnes, Norway
Raufoss, Norway
September 25, 1978
Decembers, 1980
February 5, 1981
August 25, 1981
1981
January 1982
March 19, 1982
April 13, 1982
May 1982
June 22, 1982
Augusts, 1982
August 1982
September 23, 1982
Novembers, 1982
Winter 1982/83
1982
April 25, 1983
May 15, 1983
August 15, 1983
September 28, 1983
December 21, 1983
March 1984
April 27, 1984
May 24, 1984
September 13, 1984
October 10, 1984
January 14, 1985
January 1985
February 1985
February 1985
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Table 2. Contamination Cleanup Criteria
Location Contaminant
Air
Surface
Binghamton, NY Building
Inside Vault
San.Francisco, CA
Inside Vault
Sante Fe, NM
Finland
Sweden
PCDDs/PCDFs
PCBs
PCDDs/PCDFs
PCBs
PCDDs/PCDFs
PCBs
PCDDs/PCDFs
PCBs
PCDDs/PCDFs
PCDDs/PCDFs
PCDDs/PCDFs
10 pg/m3 of 2,3,7,8-TCDD/TCDF
200 ng/m3 of PCBs
80 pg/m3 of 2,3,7,8-TCDD/TCDF
1 mcg/m3 of PCBs
10 pg/m3 of 2,3,7,8-TCDD/TCDF
200 ng/m3 of PCBs
80 pg/m3 of 2,3,7,8-TCDD/TCDF
1 mcg/m3 of PCBs
3 pg/m2 of 2,3,7,8-TCDD/TCDF
60 mcg/m2 of PCBs
24 ng/m2 of 2,3,7,8-TCDD/TCDF
1 mg/m2 of PCBs
3 pg/m23
60 mcg/m2 of PCBs
24 ng/m2 of 2,3,7,8-TCDD/TCDF
1 mg/m2 of PCBs
1 ng/m2 of 2,3,7,8-TCDD'TCDF
5 ng/m2 of 2,3,7,8-TCDD/TCDF
50 ng/m2 of total TCDF
aSum of all PCDD/PCDF isomers CI4 - CI7 with Cl substitution in the 2,3,7, and 8 positions.
A study showed that askarel fluid mix-
tures of 60% PCBs and 40% trichloro-
benzenes were combusted under vary-
ing flame temperatures. The results of
this study indicated that the optimal
temperature for the formation of PCDFs
and PCDDs is approximately 600°C. This
finding is in fair agreement with the
work done at the Midwest Research In-
stitute, where the optimal temperature
for PCDF formation from pyrolysis of
PCBs was approximately 675°C.
Under optimal conditions, PCDFs are
formed from mineral oil or silicone oil
contaminated with PCBs at >5 ppm.
PCDFs were also formed from a trichlo-
robenzene dielectric fluid that contained
no detectable PCBs. These results sup-
ported earlier laboratory work and ana-
lytical results of soot material from
transformer and capacitor fires, which
determined that chlorobenzenes are re-
quired for PCDD formation.
EPRI has also supported a major
study of the thermal conversion of vari-
ous transformer fluid formulations to
PCDFs and PCDDs. Fluids that have
been studied include mineral oil, tetra-
chloroethylene (TCE), and silicone oil,
all spiked with Aroclor 1254. One hun-
dred mcl samples were either pyrolyzed
(heated in an oxygen-deficient environ-
ment) or combusted (injected into a
flame or heated under conditions result-
ing in self-ignition). Pyrolyses were con-
ducted using a simple thermostatically
controlled apparatus, capable of accom-
modating glass or quartz tubes of di-
ameters up to 6 cm within its 9-cm-long
heated region. To simulate more accu-
rately certain catastrophic incidents, py-
rolyses were conducted at atmospheric
pressure.
Results of the EPRI study support the
proposition that tetra- and penta-CDF
yields are roughly proportional to PCB
concentrations in the starting material.
An interesting feature of the mineral oil/
Aroclor 1254 data is the clear and repro-
ducible differences between the pat-
terns of tetra-CDFs and penta-CDFs
formed by pyrolysis of neat Aroclor
1254 versus those formed by pyrolysis
of the 5,000-ppm mixture. For example,
2,3,7,8-TCDF and co-eluters comprise
16-21% of the tetra-CDF mixture formed
from neat Aroclor, but they comprise
45-55% of the mixture from mineral oil/
Aroclor. Furthermore, combustion of
biphenyl in TCE produced decreasing
net dibenzofuran as the residence time
was varied from 18 seconds to 6 sec-
onds and the wa)l temperature main-
tained at 450°C. In contrast, at 550°C,
there is a net increase in dibenzofuran
yield as residence time decreases. This
suggests that at the higher temperature,
significant dibenzofuran destruction is
occurring. There are also large effects
on dibenzofuran yield in the presence of
different solvents. Typically, yields ob-
tained with combustion in TCE are
much higher than those obtained in sili-
cone or mineral oil. Some sharp differ-
ences on the effects of particular vari-
able parameters on dibenzofuran yields
have also been noted.
Both EPA's and EPRI's pyrolytic and
combustion studies support the propo-
sition that the amount and the specific
PCDF isomers are related to the concen-
tration of and the PCB homologs in the
transformer fluid. Additional supporting
data include EPA's data on the trans-
former oil and the generated soot in the
Binghamton, NY fire incident. The data
on the transformer oil and soot from the
Binghamton fire are presented in
Table 3.
Penta-CDF concentration was approx-
imately 7% of the total PCDFs in oil.
Penta-CDF concentration increased to
31% in the soot after the fire. This find-
ing corresponds to the 52% of pen-
tachlorobiphenyls in the transformer
oil. Similar observations can be made
for the hexa- and hepta-CDF concentra-
tions in soots relative to the concentra-
tions of hexa- and hepta-chlorinated
biphenyls. The Binghamton, NY fire
data also appear to indicate that the
higher chlorinated biphenyls are more
likely to convert to chlorinated dibenzo-
furans and the lower chlorinated PCBs
are more likely to decompose in a trans-
former fire.
The finding of PCDDs in the Bingham-
ton, NY fire incident raised concerns
that PCDDs may be generated in PCB
transformers. Analyses of subsequent
PCB transformer fire incidents, how-
ever, identified only one other incident
where PCDDs have been identified. It
appears that the presence of chloroben-
zene is a requirement for the formation
of PCDDs, and fires involving trans-
formers without chlorobenzenes do not
generate PCDDs.
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Table 3. Correlation of Analytical Data on Transformer Oil and the Generated Soot from the
Binghamton, NY Incident
PCBs PCDFs
Isomer/Total PCBs Isomer/Total PCDFs
Tetrachloro- 0.15 0.013
Pentachloro- 0.52 0.31
Hexachloro- 0.28 0.45
Heptachloro- 0.04 0.21
Octachloro- 0.001 0.02
BeverlyCampbellandAnthonyl.ee are with Technical Resources. Inc.. Rockville.
MD 20852..
Brian A. West fall is the EPA Project Officer (see below).
The complete report, entitled "Characterization of PCB Transformer/Capacitor
Fluids and Correlation with PCDDs and PCDFs in Soot," (Order No. PB 87-
145 785/AS; Cost: $18.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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0000329 PS
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