Document DJNQeajK6Jz5k05wMy97VBJa

Trip Report: National Conference on Polychlorinated Biphenyls Since the enviornmental problems of polychlorinated biphenyls (PCS) were ..first raised tn the iate 1360's, a good deal of data has been accumulated ; > ..but few conclusions reached in regard to the true magnitude of the^PCB _.-i - p r o b l e m s . The complex!ty of this problem is illustrated by the major q u e s " - ; f tions which are sti11 unresolved after years of research by many highly.;; > qualified scientists. The magnitude and symptoms of PCB intoxi cat ion are. .`still uncertain. The mode of entry and transport of PCB's in the environ- . ment has not been resolved. The value (especially short-term) of point ... source controls is not clear. The real Importance of PCB's in the safety --.of, the present appl {cations Is hard to define. .This results in the dilemma .K-j'r- of PC3 control' how does one choose between ah uncertain environmental health hazard and an uncertain safety hazard?... . ; !: '"The EPA and'other agencies, unable to resolve these questions, sponsored T 'the National Conference on Polychlorinated biphenyls apparently hoping to freely exchange the latest information on PC81s and encourage a greater public awareness of this complex problem. ,y~ ' :; The conference was held in the Pick-Congress Hotel , Chicago, 111. on vu.=.' Nov. I3-2 1 ,1975. !t was attended by 400-7Q0 people from the U.S. and ; several other countries. The conference was divided Into eight topical ' .. 'sessions. `These covered Health-effects and Human exposure; Use, sources and - ; : -identification; ^environmental fate and occurrence; ecological effects and i- 'iexposure; economics and substitutes; approaches to control ; a summary 'session . and a general session. ,The General Session was an open meeting at which a n y - ^ ^ -- one who wished could speak. The speakers at this session were mainly repre^ - ; ! - sentatives of various interested citizens groups, unions, and affected :industries (fisheries and paper makers). There were some speeches b y : - " ' scientists whose papers had not been included in the other sessions. Most of these speakers urged a solution to the problems as they saw them, but were not looking necessarily for assignment of guilt or punishment of offenders. Most seemed aware of the hard choices Involved. Some of the fisheries spokesmen took the approach that while PCB's may be vital to the electrical industry ; . they were detrimental to the fishing industry.' v . The most intriguing data presented in the session on Health Effects and - -Human Exposure dealt wi th the activi ty of polychlorinated "dibenzofurans- (PCDF) . ~ Or. Kuratsone presented data which clearly showed unusually high levels of PCDF in the tissues of Yusho victims. Yusho refers to the poisoning by PCB contaminated rice oil which occurred in Japan in 1968. 2,3,7,8-Tetrachlorodtbenzofuran has been found in the blood of Yusho victims. Penta and hexachlorodibenzofuran have also been found. In a later paper, Or. John P. Moof*8fyCiJsised prel iminary resul ts of the toxicl ty of 2,3,7,8-tetrachlorodibenzofuran. PCDF appears to be several orders of magnitude more toxic than PCB's. More significantly, the symptoms of PCDF intoxication mimic the symptoms of Yusho. Since PCDF's were found in tissue from Yusho victims the evidence strongly suggests that PCDF's not PCB's were the causative agents in Yusho. 905183 n r r / A A r * Tor Dr. James R. Allen described his work bn Reproductive Dysfunction in monkeys which had been fed low levels of PCB's. The most interesting aspect of this was the close similarity of the pathology observed in these monkeys to the symptoms of Yusho and PCDF intoxication. A l len claimed, during the question period, that he did not yet have the results of the analysis for PCDF's in ^ his PC8 samples. Again,' however, there Is the suspicion that PCDF's may be the causative agents. j- ;/y .V. ^v It is tempting to point to PCDF's as the real culprit and claim that PCB's,are not at fauIt. While th.is hypothes is is an excel lent basis for further .s: research Into PCB toxici ty, it could be very dangerous as aYpubl ic posi tjon. There Is no evidence that PCDF's are hot products of PCB degradation In use, ' in the environment or in animal metabol Ism. One can claim that all PCB1s Y: Y which have been used in toxicological studies were contaminated to some extent .v; . with PCDF's and these PCDF's were the cause of the pathology observed. -On the ' other hand, it is possible that at least'some PCB Isomers can be metabolized . to PCDF's. Or. Marco Biocca's paper on Biological responses in chicken and mice showed that 3,4*5,3',4',5'"hexachlorobiphenyl mimics the toxicity of PCDF. This isomer was one of the most toxic PC8 isomers in Biocca's study. This toxicity may be intrinsic or it may be due to metabolic conversion. 3,4,5,3',4',5'"Hexachlorobiphenyl has all four ortho positions (2,2',6,6' unsubstituted by Cl. It Is just these positions which must be oxidized .Y v -Y--" to form the dibenzofuran. All the other PCB isomers in Biocca's study had at least 2 of these posItions substituted by chlorine. Or. James 0. McKinney --concludes "The rates of metabolism are considered of lesser importance than the potentially highly toxic nature of some of the intermediary and terminal metabolites such as chlorinated d 1benzofurans." Or. Robert W . Risebrough reported that Aroclors (except MCS1016) contained 0 78 "to "2 U "ppm PCDF. However, he did not find PCDF's in ducks fed the contaminated PCS's. He suggested that the PCDF's were preferentially eliminated. If so, why are PCDF's still found in Yusho victims? There may C f C T / n n k rnr 905184 y *$ be species specific physiology which explain this dichotomy but there is at the present time no answer supported by evidence. *'v It is clear that oxidation of PCB's can lead to the formation of PCDF's and that PCDF's are highly toxic. Before explaining the toxicity of PCB's-on the . basis of PCDF contamination, however, several questions must be answered. ,'- 1. Are PCDF's an inevitable and Inseparable by-product of - PC8 synthesis? - V. :---v ..y'V;-; 2. Are PCDF's produced tn transformers under normal operation? '..when-the transformer fai 1s7 ; -: "'s 3. Can PCOF's be formed by UV initiated oxidation ofPCB's exposed to ; -ai r at room temperature?. i'-^::''V \^ v--' ' k. Are PCDF's formed by metabolic oxidation of PCB's? Dr. Renate Kimbrough discussed the pathological findings associated w.i th chronic experimental exposure of PCB in rats. ' She found that the hepatic micropathology was extensive after 300 days feeding with 50mg/kg/day of Aroclor 1-254. Dr. J.C..Calandra also reported the resul ts of chronic feeding studies of PCB's in rats. .He reported that the primary pathology was the observation of neoplastic lesions in. the liver. (Note: neoplastic means new and abnormal tissue, It does not mean cancer). Calandra reported that <* no hepatocel lular carcinogenici ty was observed. ;A11 lesions except one were ' ! observed tn females. ' -yi'-b. 1r In the session on uses, sources and Identification Dr. Robert L. Durfee . . presented data on production and use ofP C B ' s in the USA. Domestic production is k 0 x 10 lb/yr, of which 7 x 10 lb/yr are exported. The remaining 33x10 lb/yr are sold to transformer manufacturers, 12x10^ lb/yr; and capacitor manufacturers 21x10^ lb/yr. The USA imports 0.5x10^ lb/yr of decachlorobiphenyl which is used in investment casting wax. Hr. Thomas E. Kopp reported that the EPA criteria for water quality which is now circulating for comments, set a goal of 0.001 ug/1.(l ppt) of PC8's in fresh water and marine aquatic environment. He also reported that there have been 23 PCB spills from transformers since 1972. Four of these from railroad transformer leaks. Or. Stephen Safe gave an overview of PCB analysis. He pointed to PCS meta bolic products notably hydroxyiated and methoxylated PCB 's as new po!lutants. Mr. Stanton Kleinert discussed sources of PCB's in Wisconsin. His conclusion -thag^J^Mciut from air may be the primary source of PCB's in Wisconsin waterways raised two questions. First, how do the PCB's get into the air? Second, what, is the value of point source control? C C 905185 4 \ ' :C 4-, v V v :vr-V; -f- j*3'i& Dr. Charles Jelinik reported the levels of PCB's In the U.S. food supply. ;v ; Since 1972 the levels In food have been decreasing except for fish where^the ; levels have remained unchanged. Today freshwater fish are the only significant dietary source of PC8's. The average dietary exposure Is lOug/day. The prob- lem however is more serious for people whose diet contains significantly more than the average content of fish. This also represents a serious threat to the commercial fishing industry. :s. , . . J ..//v/-:'// H.- v - v ? ' ' ; - . ; ' - /, ; . . . > .. . .. ^ Fish and birds appear more sensitive to PCS intoxication than most mammals , and some species of fish eating manna Is .(mlnkkare also highly sensitive.,' y.;. Biomagnification indices in fish range from 10' to 105. - PCB's do indeed appear to be ubiquitous. There is a suspicion that some '.deep water sediments are reservoirs of .PCB's and wi 11 .'continue to leak/to ;^-Vv&>/y.-S- the surrounding areas for years to come. ' Dredging Is'not always advisable/ / since often this succeeds only in dispersing' the PCB's into the water. The session on economics and substitutes contained no new information.' Dr. Dean Branson, Dow Chemical, described their 4-year program with McGraw- Edlson to develop butylated-monochlorodiphenyr oxide (XF 4169L) for capacitors. He compared only flash points to reach the conclusion that this liquid has a low risk of explosion and fire and implies that the liquid temperature must exceed the flash point to have a fire hazard. There is some concern about biodegradation of this material. - \. * Mr. Richard Montgomery, Dow-Corntng, described the!r 5-yar program to deve!op ' .-. silicone fluids for transformer use. '/Basically the presentation was the same /' / f.one given by Mr. Montgomery at' PIttsfield and Rome. Some points should be v^-K / mentioned. He announced that Dow Corning has the capacity to handle the global transformer market. In the future Dow Corning will specify silicone filled transformers for their own use. He urged an evolutionary introduction of silicones over the next 3"5 years in order to gain experience in the risk : //; of fire and explosion. He claimed that PCS filled transformers in service could be changed to silicone without problems. However, he cautioned aoainst this on an allout basis due to the environmenta1 hazards of shipping and . handl ing the PC8's. ' ' 'V Mr. Oavid Wood of Monsanto described MCS-I238 and MCS-1588 liquids for capa citor use. He mentioned the transformer candidates but gave no details. He did state the need for standards of flammability in this. area. While Mr. Montgomery's appeal was directed to the consumer, Mr. Wood's appeal was to the manufacturers. Mr. Bruno Rey-Coquais, Prodelec, claimed that a non-flammable dielectric liquid was absolutely necessary. He proposed the use of alkylated d'ichlorobi phenyl fan alkvl PrRl . Or. E.J. Inchalik, Exxon, described di-isononyl phthalate for use in capacitors. 905186 ( 5- - ln the session on approaches to control three messages came through quite clearly. One, there will be some control of PCB's, lf not by the pure waters act, then by the toxic substances control act (S -776) which Is likely to be passed. The EPA still has no clear direction and is still trying to reach a decision. The EPA would like to see the problem disappear. That is, they would be delighted If the states took action or if the public . utilities took the Initiative and brought pressure on the manufacturers. To this end EPA speakers repeatedly encouraged the concerned parties to put pressure on their state legislators and on their public utilities to end the use of PCB's. The Hon. Nathaniel Reed, Ass't. Sec.*001, was probably the most eloquent and outspoken opponent of PC8 usage. A coupie of quotes will illustrate. "We .must step back from industrial efficiency in order to step forward to environ mental improvement." "We should cease to quibble over scientific niceties and respond to the wildlife needs before It Is too late." The overall tenor of the conference was good. I had expected a good deal of criticism directed at industry. This did not happen in general. Most of the critical.commentary was directed at the EPA for doing nothing. As one speaker put It "the EPA should be congratulated for holding a conference at which they could not win." Overall however the conference could be character ized as a rational attempt to share, the latest data and Inslgnt on the effects of PCB's. Unfortunately when all Is said and done, more is said than done. W.A. Fessler 905187