Document nkqe8Q7oayGBDZ0wbO8b7EOGz

WHAT HAPPENS TO PCBa IN THE EHVIROHHEMTt By Dr. R. H. Munch Presented by W. B. Papageorge Because they can be detected by the same analytical methods, and because soma suspect that they may have similar biological afreets to DDT, polychlorinated biphenyls In the environment (PCBa) have become a cause of concern. It la, therefore, lsqportant to present data to show that PCBa do disappear from the environment. Probably the most effective way to do this Is to compare what has been put Into the environment with what la found there now. This can be done In the following way: The commercial PCB products are mixture of chlorinated biphenyl homologs containing from one to ten atoma of chlorine per biphenyl molecule. If there were no degradation In the environment, or If all homologs degraded at the aame rate, the ratio of homologs In "aged environmental samples" (samples taken at a distance from a known source) should be the same as that In the products Intro duced Into the environment. On the other hand. If the homolog ratio In "aged environment aamplea" differs from that of material produced, some process swat be opera ting in the environment to remove different homologs at different rates. Monsanto, the . Mjor U.S. producer, recently released data on Its sales of the various commercial grades of PCB for the years 1957-72. Rest- of-world sales by other producers and production before 1957 probably reprebent a similar product mix. Using the Monsanto data and known homolog analyses of each of the commercial grades, the percentage of each homolog in the total U. S. production can be calculated. ' Ihe other required datum Is an estimate of the hoswlog distribution In "environmentally aged samples." Analysts experienced in this field generally agree that material reoovered from such samples la similar to Aroclor 1294 or 1260, the Monsanto trade name for mixtures of PCBs with chlorine contents corresponding to an average of five and six chlorine atoms per biphenyl molecule respectively (1-8). In order to present a conservative comparison and because aMst analysts cite Aroclor 1254, we shall use the homolog content of that material In our comparison. HONS 04*046 -2- The homolog contents of the material produced In the 0. S. from 1957 to 1971 and that of Aroclor 1254 are tabulated below: Homolog 0 1 2. 3 4 5 6 7 8 U. S. Sales 1957 - 1971 0.1 1.3 14.8 29.9 21.9 16.1 10.5 4.2 1.1 Aroclor 1254 L. 1 <.l .5 1 21 48 23 6 HD It la apparent that the homolog ratio of the material sold la quite different from that of Aroclor 1254. - There must, therefore, be one or more processes In the environment which remove the lower homologs st much greater ratea than the higher ones. The precision of the data Is too low to permit accurate calculations of the relative rates of loss. However, It would appear that the homologs containing less than four chlorine atoms amp be degraded at rates approximately thirty tlmee those for the five and six chlorine homologs. Laboratory data whloh we hope to publish later show that the rate of bacterial degradation Is an Inverse function of the ohlorlne content for PCBs and might, therefore, be one of the degradatlve processes responsible for the relative decrease In the lower homologs. . HONS 044047 1) L. M. Reynolds, Pesticide Residue Analysis In the Presence of Polychlorinated Biphenyls Residue Reviews 24, 27, 32, 41, 42, 44 (1971). 2) R. W. Rlsebrough, P. Relche and H. S. Scott - Current Progress In the Determination of the Polychlorinated Biphenyls - Bulletin of Environmental Contamination ft Toxicology 4, 192, 199 (197 ). 3) 0. E. Baglay, W. L. Relchel and E. Cromartle - Identifi cation of Polychlorinated Biphenyls In Two Bald Eagles by Combined Oas-Llquld Chromatography-Mass Spectrometry - Journal of the AOAC 21> 251, 252, 257 (1970). 4) Albert C. Tas and Rudolf H. deVos - Characterization of Four Major Components In a Technical Polychlorinated Biphenyl Mixture - Environmental Science ft Technology , 1216 (1971). 5) Judith A. Armour and Jerry A. Burke - Method for Separating Polychlorinated Biphenyls from DDT and Its Analogs - Journal of the AOAC 763, 765 (1970). 6} Ian Prestt, D. J. Jeffrerles and N. W. Moore - Polychlori nated BlphenylB In Wild Birds In Britain and Their Arlan Toxicity - Environmental Pollution ,1, 3, 15 (1970). 7) V. Zitko - Polyohlorlnated Biphenyls and Organoohlorine Pesticides in Some Freshwater and Marine Fishes - Bulletin of Environmental Contamihatlcn ft Toxicology 6, 464, 467 (1971). ~ 8) PCBS ft The Environment - Interdepartmental Task Force on PCBe - Washington May, 1972 - COM-72-10419 - Table 6, P. 93. HONS WHAT HAPPENS TO PCB IN THE ENVIRONKENT? 1. WE CANNOT DETERMINE IF PCBe DEORADE IN m ENVIRONMENT FROM THE TOTAL CON' CENTRATIOMS FOUND THERE. 2. THE PCBe ARB MIXTURES OF HOMOLOOS. 3. THEREFORE, COMPARISON OF HCMOLOQ RATIOS IN "ENVIRONMENTALLY AOBD SAMPLES" WITH HOMOLOO RATIOS IN MATERIAL PRODUCED CAN BE USED TO UAIN INSIGHT AS TO WHAT IS HAPPENINO IN THE ENVIRONMENT. HONS 044049 HON DO HE GET THE DATA NEEDED? 1. PRODUCTION FIGURES FOR ALL MONSANTO PCB PRODUCTS AND HOMOLOG CONTENT OF EACH PRODUCT AGE AVAILABLE FOR 1957 71. ME USE THESE DATA TO CALCULATE HOMOLOG RATIOS FOR 1957-71 PRODUCTION. 2. EUROPEAN PRODUCERS MAKE SIMILAR PRODUCTS IN ABOUT THE SAME RATIOS AS MONSANTO. 3. PRODUCTION 8EF0RE '57 WOULD NOT AFFECT THE FIGURES GREATLY SINCE PRODUCT RATIOS HERE SIMILAR ANO PRODUCTION SMALLER. 4. ANALYSTS GENERALLY AGREE THAT MATERIAL FOUND IN "AGED ENVIRONMENT AL SAMPLES* IS SIMILAR TO AROCLOR 1254 OR IN RARE CASES EVEN TO AROCLOR 1260. ii MONS 044050 WOODS HOLE OCEANOGRAPHIC INSTITUTE . AROCLOR 1254 VS ENVIRONMENTAL MATERIAL CURVES AROCLOR 1254 PLANKTON K-l 9-4-STA. 10 HONS 044051 A COMPARISON OF THE HOMOLOG RATIOS FOR PCBS SOLD HITH THOSE FOUND IN AGED ENVIRONMENTAL SAMPLES HOMOLOG 0 1 2 34 56: 8 U.S. SALES 57 - '71 0.1 1.3 14.8 2S.9 21.9 16.1 10.5 4 2 1.18 AROCLOR 1254 <.l <.l <.5 1 21 48 23 6 NO HONS 0 4 4 0 5 2 CONCLUSIONS 1. THERE ARE HARKED DIFFERENCES ' BETWEEN THE RATIOS OF H0N0L06S IN PCBs FOUND IN "AGED ENVIRON MENTAL SAMPLES" AND THE RATIO OF HOMOLOGS FOR MATERIAL PRODUCED. 2. THESE DIFFERENCES CAN BEST BE EXPLAINED BY ASSUMING THAT THE PCBs WITH 3 OR LESS CHLORINE ATOMS PER MOLECULE DEGRADE MUCH MORE RAPIDLY THAN THE HIGHER HOMOLOGS. 3. THE HONOLOG RATIO DATA DO NOT GIVE INFORMATION ON THE RATE OF DEGRADATION OF'HIGHER HOMOLOGS. HOWEVER, SEMI-CONTINUOUS ACTIVATED SLUDGE TEST DATA SHOW THAT THESE TOO DEGRAOE BUT AT A SLOWER RATE. 1 HONS 044053