ES&T
OUTLOOK Phasing out PCBs Whatever the outcome of the debate over their health effects, they must go eventually
Polychlorinated biphenyls (PCBs) have been shown to be environmentally persistent and bioaccumulative. So far, however, few, if any, data have been able to link them directly to serious human health effects. Although some PCBs and their pyrolysis products have been associated with chloracne, a skin affliction, even that effect does not appear permanent, though it may last several years. Nevertheless, PCBs are ultimately to be banned in the U.S. under the Toxic Substances Control Act of 1 9 7 6 ( T S C A ) . PCBs have been used in transform ers and capacitors since the early 1930s because of their highly desirable dielectric, flame-resistant, and heat transfer characteristics. The Yusho rice oil poisoning episode in 1968 (ES&T, January 1983, p. 12A, and March 1983, p. 127A) plus the some what later discovery that PCBs persist in the environment and bioaccumulate began the chain of events leading to PCB bans in the U.S. and elsewhere. The degree of persistence increases with the chlorine content of these chemicals. Some scientists are beginning to query whether the chemical "bad ac tors" that triggered the chloracne were not PCBs but rather compounds, such as polychlorinated dibenzofurans (PCDFs), formed when PCBs are heated in the presence of oxygen. In
Addis and Komai: Compliance lowest possible cost
at the
0013-936X/84/0916-0043A$01.50/0
the Yusho incident, heat transfer oil and rice oil were mixed at fairly ele vated temperatures. Fires can subject PCBs to temperatures that may cause or enhance toxicant formation. Under such conditions, PCBs can be trans formed into PCDFs. The source of polychlorinated dibenzo-p-dioxins (PCDDs) is thought to be the result of heating chlorobenzenes, a PCB diluent in transformer fluids, to high temper atures. From the regulatory standpoint, any proof of whether PCBs are very dan gerous or completely innocuous is now immaterial. As Gil Addis and Ralph Komai of the Electric Power Research Institute (EPRI, Palo Alto, Calif.) told a conference on PCBs that they orga nized and held at Atlanta, Ga., in De cember, "It does not matter whether you think laws and regulations con cerning PCBs are unjust. The rules are the rules, and our job is to bring about compliance at as low a cost to electric utilities as possible." Health effects This could be worded, "What health effects?" according to John Brown of General Electric (GE). He observed that "now, we have five times as much information on PCBs as we did when Congress took its action against them in 1976. This includes several studies on extensively exposed human popu lations." Brown outlined a G E study involv ing 152 male and 42 female capacitor workers who had been exposed to Aroclors 1016, 1242, and 1254—listed in ascending orders of chlorination— for periods of 2-35 years. These indi viduals were found to have absorbed a minimum of 2.5-88 g of the lower chlorinated PCBs and 0.1 -1.2 g of the higher PCBs. These values were re ported for blood; however, Brown said
© 1984 American Chemical Society
Rules and rulemaking Removing all PCBs in the U.S. would be a formidable task; about 758 million lb are still in use, mostly as capacitor and transformer dielectric fluids. Moving in this direction, however, EPA promulgated certain regulations on Aug. 25, 1982. For example, large high-voltage capacitors and PCBcontaining capacitors near human food and animal feed must be replaced by Oct. 1, 1988. PCB-containing trans formers near food and feed must be removed by Oct. 1, 1985. However, there is no date for retrofilling and re placement of nonleaking transformers located in places of restricted access. In those cases, PCBs may stay for the transformers' useful Under a court order,lives. EPA's Office of Pesticides and Toxic Substances must develop regulatory strategies con cerning PCB fires, PCB substitutes, retrofilling, replacements, and other aspects. An Advance Notice of Pro posed Rulemaking is expected this March and proposed regulations are expected in October. Final rules are scheduled for July 1985.
that from them, concentrations in fatty tissue could be calculated. He told ES& Τ that the ongoing study began in 1976 and that a report should appear in Environmental Health Perspectives later this year. "Despite this massive dosage, we observed neither chloracne, nor any rise in serum lipids," Brown added. "The latter would be found if there were a liver dysfunction or any evi dence of cardiovascular or pulmonary effects. What we did see was a slight transitory induction of drug-metabo lizing enzymes, prolonged retention of Environ. Sci. Technol., Vol. 18, No. 2, 1984
43A
the higher PCB congeners, and clear ance of most of the lower PCBs. The absence of chloracne should not be surprising. If PCBs themselves could cause it, we should have been seeing lots of it since the 1930s, when their widespread usage began." Brown described a National Insti tute for Occupational Safety and Health ( N I O S H ) study of the mor tality of 2567 people who had worked with PCBs during the period 1938 75, representing a total of 39 018 per son-hours of exposure. Of these, 60 had died of cardiovascular causes, 39 of cancer, 13 in accidents, 11 of ner vous system involvements, and 40 of other causes. Statistically, N I O S H had "expected" 62.93 cardiovascular, 43.79 cancer, and 12.95 nervous sys tem death causes. "There were also no significant increases in any individual kind of cancer," Brown said. That Study was published in 1981. Retrofill or replace? Richard Addison of the Bedford Institute of Oceanography (Dart mouth, Nova Scotia, Canada) listed and discussed potential environmental effects of 14 PCB replacement fluids for transformer and capacitor dielec trics and other uses (ES& T, October 1983, p. 487A). They consisted of six aromatics, four ester-based m; terials, two paraffins, and two silicones. In addition, one replacement consists of perchloroethylene, which is recom mended for transformer replacement only, not for retrofilling. Which course is more advanta geous—to retrofill an existing trans former with a replacement fluid or to replace the transformer entirely? Pa cific Gas & Electric ( P G & E , San Francisco, Calif.) decided to replace its PCB-filled distribution capacitors and network transformers containing PCB fluids. This could cost the utility mil lions of dollars, and final disposal of PCBs from the equipment being re placed will add to this cost. In general, P G & E elected to use silicones as sub stitute transformer fluids. At least four other utilities are expected to follow suit. T. L. Forrester of P G & E said that depending on the type of fluid used, retrofilling may allow existing equip ment to be used. Advantages of retro filling include no major construction, less cost and need for added manpow er, and, possibly, less media and public attention. One problem is that of re sidual PCBs. If a transformer is re placed, on the other hand, the PCB problem disappears, but then one faces lengthy, costly construction work. 44A
Environ. Sci. Technol., Vol. 18, No. 2, 1984
Field testing According to EPA's rules—^pres ently under litigation—a "non-PCB" transformer's fluid contains < 50 ppm PCBs; a "PCB-contaminated" trans former has 50-500 ppm, while "PCB transformer" fluid contains > 500 ppm PCBs. Several techniques for rapid field testing for and analysis of PCBs are now available. For example, a transformer user can now quickly get a general idea whether there are < 50 ppm through a system devised by EPRI and mar keted by Dexsit Chemical Corporation (Hamden, Conn.). The key is a reaction between mercury(ll) nitrate and an organic reagent. The former forms a blue complex with the latter to indicate that < 18.5 ppm CI, approximately equivalent to 50 ppm PCBs, are present. A colorless result indicates the presence of > 18.5 ppm Ci. Manleh Engineering Corporation (Woburn, Mass.) also offers a kit for rapid testing for the existence of a PCB problem. Jim Picker of S-Cubed (La Jolla, Calif.) said that his firm has developed a portable field system which detects Aroclors (Monsanto's trade name for PCB chemicals) by gas chromatogra phy (GC) and electron capture* NUS Corporation (Gaithersburg, Md.) uses a similar technique. Mark Denton of C/S Associates, Inc. (Oak Ridge, Tenn.) discussed a portable IR field monitor which uses a horizontal mul tiple internal reflectance (HMIR) stage and an evaporative fixed-film sample application, capable of determinations to 2-5 ppm. Other companies offering field systems for PCB testing or de struction include McGraw-Edison (Pittsburgh, Pa.), ΕΤΙ of North America (Overland Park, Kan.), IT Corp. (Knoxville, Tenn.), and others.
Removal and disposal After equipment retrofilling or even a spillage, disposal of PCBs and PCB-contaminated material is re quired. After replacement, both fluids and capacitor and transformer "car casses" must be disposed of. For PCBs, incineration above 1200 °C is pres ently the only permissible option. PCB-contaminated materials ( < 500 ppm) and carcasses may be disposed of in secure landfills. A spokesperson for S U N O H I O (Canton, Ohio) told ES&T that chemical destruction technology for PCBs in the 5002500-ppm range has proven successful and is available commercially. Inci dentally, T S C A does not specifically
address cleanup technologies. Leo Weitzman, research manager of Acurex Waste Technologies, Inc. (Cincinnati, Ohio), says that for chemical transformer oil cleanup, his company's technique is to use sodium metal as a reagent to strip off chlorine and "salt out" sodium chloride. The finely divided sodium attacks PCBs dissolved in a proprietary solvent; the reaction occurs under a nitrogen "blanket." For capacitors, a mobile approach soon to be demonstrated will use sodium metal also under a nitrogen blanket to strip chlorine. S U N O H I O , S.D. Myers, Inc. (Akron, Ohio), PPM Inc. (Tucker, Ga.), and several other companies are also using chemical destruction. A major advantage of chemical PCB destruction is the ability to reclaim the rest of the dielectric fluid. In addition, a thermal technique that produces high-grade gaseous or aqueous HC1 is available (ES& T, July 1983, p. 290A). Microbial treatment Suppose PCBs contaminate soils or sludges, which cannot be cleaned chemically and are very expensive to incinerate. Microbes might be an an swer. Walter Kim of the National Aeronautics and Space Administra tion (Cleveland, Ohio) said that at tempts to decompose PCBs in sewage sludge with Pseudomonas aeruginosa were unsuccessful. The bacteria ap parently absorbed the PCBs, but re leased those compounds after they died orlysed. On the other hand, Donna Bedard of G E reported the isolation of more than 12 strains of PCB-degrading bacteria from sites containing PCBs. Two of these, a Corynebacterium species and Alcaligenes eutrophus, degrade a number of PCBs, including several pentachlorobiphenyls. She postulated that the A. eutrophus uses a previously unknown dioxygenase enzyme to attack at the 3,4-position, while the Corynebacterium may at tack at the 2,3 site. Breakdown prod ucts seem to include chlorobcnzoic acids, which should be amenable to further microbial decomposition. Bedard suggested that bacteria ex posed to more highly chlorinated PCBs may already have developed an ability to decompose congeners previously thought to be refractory to biodégradation. She said that studies are under way at G Ε to gain a full under standing of the genes that govern pro duction of PCB-degrading enzymes and of the biochemical pathways of this degradation. —Julian Josephson
