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COMFIDEHIAL Analytical Chemi stry Special Study 71-2 * Job No. 13400 MCS 10.16 - AN ENVIRONMENTALLY COMPATIBLE AROCLOR INTRODUCTION The objective of this report is to bring together all the informa tion, so far generated by Monsanto, et al, that supports the contention that an environmentally compatible Aroclor can be manufactured. The product would be designed for use in areas where its industrial properties are unigue enough to merit close control of the amount of material allowed to escape into the eco system. , SUMMARY The information present in this special study report demonstrates that, from an environmental viewpoint, MCS 1016 is at least 10 times better than the current product Aroclor 1242 and in turn 75 times better than Aroclor 1254. The above conclusion is based on the rather simplified assumption that the major environmental hazard associated with polychlorinated biphenyls (PCB's) is their ability to resist metabolic and nonmetabolic degradation. The resistance of the PCB's combined with their high lipid solubility in turn leads to their undesirable biological build up toward the end of the exposed food chain. RESULTS AND DISCUSSION Polychlorinated biphenyl products are produced by direct chlorina tion of biphenyl which means that there exists in all PCB products at some level every conceivable isomer. The biphenyl ring structure (Figure I) can have theoretically 0-10 chlorine atoms substituted on it in any of the positions designated by the numbers on the ring. Assuming that the phenyl rings can rotate freely about the 1,1'bond whatever the number and positions of chlorine substituents it can be calculated that there are 210 possible isomers. The distribution of these isomers according to the number of chlorines per biphenyl molecule is shown in Table I, column 1. Figure I 32 2' 3* 65 6' 5' PLAINTIFF'S NEV Q260 O 739323 `. - TA Special Study 71-2 Page 2 TABLE I Homolog NO. of Cl Per Bi phenyl Molecule Dist. of Dist. of Most Theoreti Probable cal PCB PCB Isomers Isomers Dist. of Most Probable PCB Isomers found in Nature Dist. of Most Probable PCB Isomers (3oOxidized by c2 Dist. of Identi fiable PCB Isomers Absent in Tissue Extracts 01 1 1 3 ' 3 2 12 6 3 24 18 4 42 21 5 46 36 6 42 21 7 24 18 8 12 6 93 3 10 1 1 36 21 18 6 - 1 3 5 11 4 5 1 -- 1 3 9 4 - -- Total: 210 130 81 30 17 The number of possible isomers can be reduced from 210 to 130 by further assuming that the most probable structures are those where the number of chlorine atoms on the two rings differ by not more than one. The distri bution of the most probable structures are shown in Table I, column 2. Of these 130 most probable isomers, the ones of further interest are those that have 5-B chlorine atoms per biphenyl molecule. The reason for this lies in the fact that PCB's containing 5-8 chlorine atoms are the most refractory toward degradation as witnessed by what has and is being found in "weathered" biological materials. This leaves a total of 81 isomers that are the cause of the undesirable biological build up phenomenon. The isomers of concern are listed in Table I, column 3. With this information in hand, it is instructive to discuss the homolog distribution of Aroclor 1254, Aroclor 1242 and the replacement fluid MCS1016. This distribution is shown in Table II. Some simple arithmetic with the numbers in Table II shows that ^75% of Aroclor 1254, M.0% of Aroclor 1242 and only ^1% of MCS 1016 are the refractory PCB isomers that are responsible for the biological build up. CONCLUSION "MCS 1016 can decrease the level of refractory PCB isomers currently being released to the environment from use of Aroclor 1242 and Aroclor 1254 by factors of 10X and 75X, respectively." To further verify the above conclusion, a number of research programs have been instituted which include studies of bacterial degradation of the products in question by natural and accumulated bacteria as well as some work involving rat metabolism. NV 026069 739324 # Homolog No. of Cl Per Biphenyl Molecule 0 1 2 3 4 5 6 7 B 9 10 Special Study 71-2 Page 3 _______ TABLE II HOMOLOG DISTRIBUTION OF AROCLOR PRODUCTS * Aroclor * 1254 0.05 \ 0.06 0.32 0.78 22.99 47.38 19.75 4.62 3.96 Aroclor** 1242* 0.01 0.70 15.50 49.40 24.80 8.70 0.85 - MCS* * 1016 0.02 1.00 19.70 57.30 21.20 0.80 0.05 - Aroclor 1221 19.00 54.10 20.40 3.90 2.30 0.25 - * Spectroscopy Special Study **Memo, E. M. Emery to R. E. Keller, 1-22 -71. Accumulated Bacterial 1Degradation^ It has been demonstrated in the laboratory that a number of single PCB isomers and simple binary mixtures can be co-oxidized in the presence of biphenyl by a biphenyl degrading organism, C 2* The metabolic oxidation of biphenyl by C 2 is believed to occur as shown in Figure II. The technique employed in these studies is a standardized shake flask procedure described in detail in the referenced report. The results of these studies have suggested that the structure of the ^MCL Review report, "Biodegradability of Polychlorinated Biphenyls", J. H. Ma inprize, Reference No. MP10103. Known Pathways NEV 02&70 739325 o * Special Study 71-2 Vage 4 ________ most highly chlorinated PCB that will undergo at least primary degradation by C 2 is* Figure III Cl vCl Cl% Cl Furthermore, all other Cs. degradable PCB's can be arrived at by progressively removing chlorine atoms from the structure in Figure III. This means that of the 130 most probable PCB isomers, 30 alone can be co-oxidized by this single culture, C*. The distribution of these isomers is shown in Table I, column 4. Long term exposure of MCS 1016 and Aroclor 1242 to C 2 has indicated that the order of degradability is MCS 1016>MCS 717*>MCS 762*> Aroclor 1242. Conclusion "The dominant isomers present in MCS 1016 can undergo at least primary bacterial degradation." Natural Bacterial Degradation Two techniques which are believed to more closely simulate actual environmental situations are also currently under investigation, Semi-Continuous Activated Sludge Testing (SCAS) and river die-away (RDA) exposures. The decay of Aroclor 1221, Aroclor 1242 and Aroclor 1254 exposed to the natural biological population of river water was briefly studied in the following manner. A five gallon supply of natural water was obtained from the Meramec River, and after allowing the sediment to settle for two days, the water was decanted into another container, remixed, and 200 ml aliquots placed in the appropriate number of 16 oz. wide mouth bottles. The bottles were then spiked with 250 ppb of Aroclor 1221, Aroclor 1242, and Aroclor 1254 by injecting 0.5 ul of a 10% (w/v) solution in ethanol and 4 ppm of LAS reference #2 (Dodecene-1) added as an internal standard. After swirling to mix, the bottles were then loosely covered with foil and placed in a cardboard box. Duplicate distilled water controls were prepared with no LAS as were river water and distilled water controls containing LAS but no Aroclor. *Chlorinated biphenyl test materials intermediate in chlorine content with respect to MCS 1016 and Aroclor 1242. NEV Q2Q71 739326  Special Study 7J-2 Page 5______________ One bottle from each set was then analyzed on a weekly basis. The analysis consisted of extracting the bottle and contents with three 50 ml portions of hexane, diluting or concentrating the combined extracts to the appropriate volume and measuring the residual Aroclor by electron capture gas chromatography. Additionally, the LAS was monitored by methylene blue chloroform extraction method. Neither Aroclor 1242 nor Aroclor 1254 disappeared at a measurable rate under the conditions of this experiment. However, the results of the EC/GC analysis for Aroclor 1221 are shown in Table III. Figure IV is a normalized composite of the EC chromatograms for the Aroclor 1221 river water and distilled water exposures. Figure V is just a plot of the disappearance rate. LAS disappearance was normal in all cases. TABLE III Aroclor 1221 River Water Distilled Water ppb Aroclor 1221 ?U I J b 246 121 77 28 269 167 152 101 Although MCS 1016 was not available at the time this study was carried out the results are pertinent since MCS 1016 is intermediate in chlorine content with respect to Aroclor 1221 and A id clor 1242. The homolog distribution of Aroclor 1221 is shown in Table II, column 4. Conclusion "The RDA disappearance rate of MCS 1016 should.fall somewhere between those observed for Aroclor 1221 and Aroclor 1242." Semi-Continuous Activated Sludge Tests The details of the SCAS test procedure are outlined in Physical Chemistry Method 70-16. Briefly, the test consists of observing the disappearance rate of the material in question exposed to a bacterial sludge being feed a synthetic sewage mixture and aerated. Some samples of the results obtained via this test are shown in Table III to give the reader a feeling for the disappearnace rates which have been observed for similar non-chlorinated aromatic materials. To date, the results from tests with MCS 1043*, MCS 1016, Aroclor 1242 and Aroclor 1254 have allowed the following conclu sions 2 to be drawn: -Significant evidence of biodegradability was found for MCS 1043. Significance level used - 95ft. . 2 "Analysis of Biodegradation Data", Statistics Special Study 70-22, J. D. Hinchcn. m 739327 *3 * Special Study 71-2 Page 6____________ -MCS 1016 and Aroclor 1242 showed evidence of biodegradation but neither was significant at 95%. -Aroclor 1254 showed no evidence of biodegradation. Test Material TABLE IV * Exposure Disappearance Level Rate (24 Hrs.! Linear Alkyl Benzene Sulfonate (Dodecene-1) 20 Mg >99% Biphenyl Isopropylated Biphenyl Mixture Hydrogenated Terphenyls 5 Mg 10 Mg 10 Mg >95% 79% 49% Determination of PCB Residues in Hats Fed Aroclor 1242, Aroclor 1 2 5 4 , and Aroclor 1260-* j ~ The rat tissue samples were analyzed after extraction by electron capture gas chromatography as outlined in Analytical Chemistry Method 70-1. Upon completion of the electron capture work all tissue extracts, for each Aroclor fed, were combined and concentrated. The concentrates were then further purified via liguid chromatography and subjected to high resolution gas chromatography on a support coated open tubular (S.C.O.T.) column to identify as many of the unaffected isomers and homologs as possible. The results of this study demonstrated that the residual PCB levels in all rat tissues (fat, kidney, muscle, and liver) decrease significantly as the degree of chlorination and the dietary exposure level of the material fed decreased. Additionally, it was observed that the amount of isomeric alteration increased as the degree of chlorination decreased resulting in the fact that major PCB isomers retained by the rats fed Aroclor 1242 were those predominantly present in Aroclor 1254 and Aroclor 1260. The distribution of the PCB isomers that were not retained in the composite tissue extracts are shown in Table II, column 5. Most important to note is that the 4 , 4 '-dichloro and the 2,6-dichloro biphenyl isomers, which cannot be theoretically co-oxidized by the C 2 bacteria, were metabolized and/or excreted by rats. 3 "Determination of Polychlorinated Biphenyl Residue#s in Rats From 30 Day Aroclor Feeding Studies", Analytical Chemistry Special Study 70-17, E. S. Tucker. NV 026073 739328 ir- Special Study 71-2 Page 7____________ Although the action of living organisms on polychlorinated biphenyls represents an important route for their disappearance from the environment, it is by no means the only degradation pathway avail able. Many other factors in the environment such as interaction with light, air, water, soil, dust, and heat which have not been investigated may also contribute to. the nonmetabolic decomposition of th materials in question. db Monsanto Company Organic Chemicals Division Applied Sciences Section St. Louis, Missouri 2/71 - E. S. Tucker NEV 026074 739329 s?. e l ~f \s 739330 o X 'o ro TMt ctv'-vrr. 9 739.?.?1