Document 0gLoDVZvVEnbNvZOmKR1Z0mJk

Exhibit C 1 U n j~ BACKGROUND to . th REGULATION '.a,.r * - i of -J.. POLYCHLORINATED BIPHENYLS (PCB) 1 in Canada A report of the TASK FORCE on PCB, Aprili 1 ! 1976 to the ENVIRONMENTAL CONTAMINANTS :: COJMMITTEE lI of ENVIRONMENT CANADA and HEALTH & WELFARE CANADA I - /j j\= ncjcr cc"r'cnen*5 or a n t*e nrobucis Table 29 except Aroclor 1254 , which is mostly HfBP. The discontinued products Aroclor 1248 and 1260 are no doubt In-use 1n eoulpment still in service. Aroclor 1260 is almost entirely f HCBP; Aroclor 1248 contained major amounts*of Hr.BP, i Such reports as are available suggest that PCR in v'-1 waxes/resins for use in the investment casting process is i. mostly HCSP, and may contain a high proportion of decachlo^o- i biphenyl. I i 7.3.6. Chemical soecies of particular toxlcological[ Importance in contained/or derived from commercial PCR 7.3.6.1. Chlorodibenzofuran (CDBF) Certain CDBFs are known to he highly toxic to animals. CD8Fs are known to be nresent in many cqnmercial PCB samples. There is no reason to believe that the particular CDRFs in commercial PCBs are other than highly toxic. i IThere are no authenticated reports of CDBF in environmental samples. However, it is reported (Kuratsune 1975) that the PCB-based heat transfer fluid that was the cause of the Yusho Incident contained exceptionally high levels of CDBF. It appears that much of the CDBF had been generated (luring use of the fluid in this high-temperature application. Three patients with | jYusho who died between 1969 and 1972 were all shown to contain chlorinated dibenzofurans. The occurrence of CDBF in coirniercial PCR has been investigated (Bowes et al. 1975); Table 30 renroduces the data. TABLE 30 Chlorodibenzofuran Concentrations in Coirniercial PCB Samples. PCB Aroclor Aroclor 1254 Aroclor 1254 CO INI COBF Concentration 4C1 5C1 6C1 Total 0.5 1.2 0.3 2.0 1. ' 0.1 0.2 1.4 .! 1.7 0.2 0.4 0.9 : 1.5 *tltrfjt i ' ;;y -M 'J GENP 004996 aenyarochlorlnation mechamism would yield dichloro- and tri chiorodi benzofurans. Transformers and capacitors that reouire PCB fluids normally operate at elevated temperatures uo to 150PC. Power surges in these units are not uncommon and result in temperature excursions, internal arcing, electri cal failure or mechanical rupture according to severity. The Task Force is not aware of any studies of the effects of service on the composition of askarels witjh particular reference to CnaF content. 7,3.6,2. 5ingle isomers nf particular homologs Eacfj of the toxicological effects attributed to PCB Is probably comprised of contributions from a number of single isnmers of the various chloro-homologs present. If, relative to the properties of other PCR isomers, some particular isomer manifests both the ability to cause exceptionally severe biological effects i and an exceptional degree of environmental persistence, then it is likely that the oresence of that isomer in environmental samples at concentrations capable of causing significant harm would he unrecognized unless i special procedures were adopted. The adoption of Such special procedures would pre-suopose knowledge of the existence and properties (including biological) of the particular isomer. Information ehout t^e toxicological properties of individual chi o r o M phenvl s is. limiter*, end there is not yet evidence that any one of them known to he nresent in commercial PC3 causes exceptionally severe effects to the degree contempi ated in the oreceding paragraph. However, a chlorobiphenyl of exceptional persistence (i.e. stability to attack) may well not manifest any especially severe toxicological effects except those associated with very I are Innq f p rr- p v on r'1jfn ; irh r ff0ctS t rC 1e ''t 1'kn1v *0 7^3912 GENP 004997 hydrcxylatsd PC3s are expected to he more readily degraded in the environment than PCBs themselves, Jans son et al. (1974) have rsoorted the detection of such hydroxylateri compounds in seal and guillemot. Metabolic studies with PfBs have shown that dihydroxy metabolites are formed and that epoxides (arene oxides) are intermediates. It is known that the carcinogenic action of some chemicals is through their epoxide metabolite. Further studies in this field are likely to be of particular importance in deciding whether any initial control actions recommended by the Task Force should be revised at a future date. In particular, if arene. oxide (Safe et al. 1975) formation proves to be a necessary steo in the "carcinogenesis process" the occurrence in fish of PCB residues which are metabolised by this route is of crucial importance. A reasonable probability of arene oxide formation from a PCB requires the presence in the molecule of two vicinal unsuhstituted carbon atoms. Among the structures that have been shown to be present in comnercial PCBs, unsuhstituted'vicinal carbon atoms are likely to be found only in molecule* containing fewer than six chlorine atoms. Because di- and tri- chlorobiphenvls are relatively non-persistent in the environment, human exposure to PCBs lively to give rise to arene oxides, centres on ingestion of tetra- and pentachlorobipher.yl in fish used as food. Every effort should therefore be made to establish what are nresent levels cf these compounds in fish, to monitor trends through rsexan*nation cf existing chromatograms and through fresh analyses, and to determine whether (nr which) present user, ot '`.reelor 101 p and * r -r t .y- i r. ?, t ' c i*. are leading 773913  w - r i 1.1 l u 1.1 ere complex mixtures/ This is one of the factors that must be considered not only in the immediate deliberations of this Task Force, but also in applying the truly^prevent!ve aspects of the Environmental Contaminants Act in evaluating new commercial substances. Similar complicating factors nave recently been noted in evaluating the hazards from chlordane and, earlier, toxaphene. 7.3.7. Consumption and Usage of Lower Chlorinated and Higher Chlorinated PCRs 7,3,7.1. Total PCB usage. 1957-1974 Total Canadian imports of PCB for the oeriod 1957-1974 are estimated at: ' 22,000 tonnes, comprising 13,500 tonnes Aroclor 1254/1260 types ,8,500 tonnes Aroclor 1016/1242 types ll.S, domestic sales for the same oeriod are estimated at: 1 330.000 tonnes, comprising 110.000 tonnes Aroclor 1254/1260 types 1 220.000 tonnes Aroclor 1016/1242 types 7.3.7.2. PCB usage 1973 and 1974 and usage ratio Data for 1973 and 1974 reflect the effects of Monsanto's sales curtailment and show that usage ratios of 1016/1242: 1254/1250 have altered markedly in the U.S.A. though not in Canada. Average import of hulk PCR into Canada per year 1968-70: 1750 tonnes 1973-74: U 5 0 tonnesAverage n.S. domestic consumption of PCBs 1968-70: 31,000 tonnes. 1973-74 : IE .500 tonnes GENP 004998 773914