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- ------- 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- ------- 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 ------- 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. ------- 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 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 BULK RATE POSTAGE & FEES PA EPA PERMIT No G-35 Official Business Penalty for Private Use $300 EPA/600/S2-87/004 0000329 PS ------- |