Document bBZMx56zzYJEbRYgN7rKawGq3

POLYCH LQ RINATED_BIPHENYLS A PERSPECTIVE John H, Craddock Monsanto Company PCB's (polychlorinated biphenyls) have received considerable attention over the past decade because of the public's concerns over their possible effects on the environment and human health, These concerns PCB'sHAVE PROMPTED A SEARCH FOR ANSWERS TO MANY QUESTIONS ABOUT AND HOW THEIR EFFECTS CAN BE CONTROLLED, PCB' PCB `This presentation will broadly discuss s and outline the PCB'problem and issues in the United States, Hopefully., it will put s into perspective so that you as individuals can make your own informed JUDGEMENTS ON THESE ISSUES, Chemistry and Structure . PCB' ? PCB' .First, what are s The term polychlorinated biphenyls, or s REFERS TO A CLASS OF ORGANIC CHEMICALS INTRODUCED INTO UNITED STATES industry in 1929, Chemically, the compounds are made up of carbon. HYDROGEN AND CHLORINE ATOMS. THESE ARE ESSENTIALLY ARRANGED AS 2-6 MEMBERED CARBON RINGS JOINED TOGETHER THROUGH 1 CARBON ATOM ON EACH RING. I.E.. A SUBSTITUTED BIPHENYL MOLECULE. IN THE BIPHENYL MOLECULE EACH REMAINING CARBON ATOM HAS ATTACHED TO IT ONE HYDROGEN ATOM. WHEN H CTHESE ATOMS ARE CHEMICALLY REACTED WITH CHLORINE TO SUBSTITUTE A l ATOM FOR A H ATOM. PCB'S RESULT. __ .- Thus, the biphenyl ring is composed of: MAE 0102*5 1/22/81 STLCOPCB4031254 Page 2 2-6(a) MEMB6RED RINGS OF CARBON ATOMS. (b) The two rings'are joined through one carbon atom on each ring, (c) The remaining 10 carbon atoms have attached to each a hydrogen atom capable of undergoing a chemical substitution reaction by CHLORINE, Because of the possible variations that can occur in substitution of 10 H CTHESE AVAILABLE ATOMS BY l ATOMS/ I.E./ COMBINATIONS AND PER 209MUTATIONS/ IT IS THEORETICALLY POSSIBLE TO FORM DIFFERENT CHLOROB1PHENYL MOLECULES, `, Commercially produced PCB's consisted of mixtures of these 209 possible PCBINDIVIDUAL MOLECULES; HOWEVER/ ONLY ABOUT \ OF THE THEORETICALLY POSSIBLE 209 ISOMERS ARE FORMED DURING COMMERCIAL PCB MANUFACTURE. PCB 21X-60ZCommercial mixtures contained from chlorine (an average of 3-5 CHLORINE ATOMS PER MOLECULE). .. PCBCommercial mixtures typically could contain various contaminants DEPENDING UPON THE PARTICULAR PROCESS USED FOR MANUFACTURE. THESE IMPURITIES INCLUDED VARIOUS POLYCHLORINATED DIBENZOFURANS (PCDF's) AND CHLORINATED NAPHTHALENES/ WHICH HAVE BEEN IMPLICATED AS BEING AT LEAST PARTLY RESPONSIBLE FOR SOME OF THE TOXICITY REPORTED FOR PCB'S, I'll have more to say about these impurities later. Properties and Uses PCB'SThe CHEMICAL AND PHYSICAL PROPERTIES OF ARE VERY UNIQUE AND IT IS THESE UNIQUE PROPERTIES THAT HAVE LED TO ITS WIDESPREAD USE. HAE 010246 STLCOPCB4031255 Page 3 PCB'S ARE CHEMICALLY INERT; STABLE AMD FIRE RESISTANT, THEY HAVE A VERY LOW VAPOR PRESSURE (BP RANGES 2750-42500. THESE COMPOUNDS FUNC TION UNIQUELY AS DIELECTRIC INSULATORS TO ACT AS NON-CONDUCTORS OF DIRECT ELECTRIC CURRENT, THESE PARTICULAR PROPERTIES MADE THEM IDEALLY SUITED FOR ELECTRICAL APPLICATIONS WHERE HIGH-VOLTAGE ARCING COULD OCCUR; AND RESULT IN FIRES AND/OR EXPLOSIONS; DAMAGE TO EQUIPMENT AND CREATE SIGNIFICANT HAZARDS TO HEALTH AND LIFE, AS THE UNIQUE PROPERTIES OF THIS MATERIAL BECAME MORE FULLY UNDERSTOOD; MANY ADDITIONAL USES WERE FOUND, THEIR FIRE-RESISTANT NATURE MADE THEM AN EXCELLENT CHOICE FOR USE IN HYDRAULIC AND HEAT TRANSFER fluids, Their inertness imparted long-lasting qualities to lubricants, They also improved the waterproofing characteristics of surface coat ings AND OFFERED SIMILAR AND OTHER BENEFITS TO THE MANUFACTURERS OF CARBONLESS-. COPY PAPER; PRINTING INKS; PLASTICIZERS AND SPECIAL ADHESIVES. ' DlSIBIBU-LOtt PCB'Over four decades, s aevolved as truly unique class of chemicals WHICH MET BOTH IMPORTANT SOCIETAL AND INDUSTRY NEEDS. It WAS WITHIN THIS FRAMEWORK THAT MONSANTO AND OTHER PRODUCERS DEVELOPED A GROWING, WORLDWIDE BUSINESS FOR THESE VERSATILE PRODUCTS. FROM 1930 TO 1977, WHEN PCB MANUFACTURE CEASED IN THE U.S., ABOUT 1.4 BILLION POUNDS OF PCB'S WERE PRODUCED. IT IS ESTIMATED BY VARIOUS SOURCES THAT OVER HALF OF THOSE ARE STILL IN USE TODAY IN ELECTRICAL TRANSFORMERS AND CAPACITORS, MAE 01024? STLCOPCB4031256 Page ^ A 1979 Treport by he National Academy.of Sciences Listed Monsanto Industrial Chemicals Company as historically the only important U.S. PRODUCER OF PCB'S. MONSANTO'S PLANTS WERE LOCATED AT ANNISTON, PCB'Alabama, and Sauget, Illinois, where production of s ended in 1970 and 1977, respectively. t PCB's have also been produced, imported or exported by a number of OTHER COUNTRIES, OTHER PRODUCING COUNTRIES WERE ITALY, FRANCE, JAPAN, Great Britain, Austria, Czechoslovakia, West Germany, Spain and the U.S.S.R. : '4 PCB'According to the U.S. Environmental Protection Agency, s were IMPORTED FOR USE BY FINLAND, NEW ZEALAND, CANADA, FRANCE, ITALY, Norway, Sweden and Great Britain. Countries which have exported PCB's include France,'Italy and Great Britain. Many European countries still allow, and in some cases, require. use PCBOF EQUIPMENT FOR CERTAIN APPLICATIONS. THESE REQUIREMENTS ARE BASED UPON THEIR OWN RISK/BENEFIT ASSESSMENTS OF THESE COMPOUNDS, Risk/Benefii PCB'The risk/benefit issue with respect to s is the kei to the whole PCB problem. Much soul-searching is being done to define these PARAMETERS FOR PCB'S, THE BENEFIT SIDE OF THE EQUATION IS PERHAPS THE EASIER OF THE TWO TO DEFINE. MAE 010248 STLCOPCB4031257 Page 5 W PCB'e know the; benefits of using non-fl-ammable s in certain key X AND ESSENTIAL INDUSTRIES WHERE TECHNICALLY SUITABLE REPLACEMENTS ARE NOT READILY AVAILABLE. WE CAN CALCULATE THE BENEFIT OF PREVENTING FIRES AND SAVING LIVES1 IN! !: : i HIGH-RISE BUILDINGS., HOSPITALS., SCHOOLS UNDERGROUND UTILITY TUNNELS UNDERGROUND TRANSPORTATION FACILITIES/ E.G,/ SUBWAYS/ TRAINS/ RIVER TUNNELS/ PARKING GARAGES HYDRAULIC SYSTEMS OF AIRPLANES AND OTHER PUBLIC TRANSPORTATION UTILITY POWER TRANSMISSION AND DISTRIBUTION CENTERS * HOW DO WE QUANTITATIVELY MEASURE RISK ~ RISK OF HUMAN HEALTH HAZARD RISK OF ENVIRONMENTAL DAMAGE/ ETC./ AND/ COMPARE THEM WITH BENEFITS? PCB' ,This risk/benefit problem is not unique to s but confronts us WITH MANY CHEMICALS AND MANY ASPECTS OF LIFE/ WHETHER IT'S A NEW MEDICAL/SURGICAL PROCEDURE/ A NEW (OR OLD) CHEMICAL/ A NEW TOY OR AUTOMOBILE OR A NEW GADGET OR WORK-SAVING APPLIANCE, ENVIRONMENTAL AND HEALTH CONCERNS In THE LATE 1960'S/ SOME 40 YEARS AFTER PCB'S WERE INTRODUCED/ THE FIRST SIGNS OF POTENTIAL ENVIRONMENTAL PROBLEMS TURNED UP IN TWO SEPARATE EVENTS -- ONE IN JAPAN/ THE OTHER IN SWEDEN. MAE 010249 STLCOPCB4031258 Page 6 Swedish Findings The first sign of trouble was reported by a Swedish biologist. While USING A NEW AND THEN TOTALLY UNIQUE TECHNIQUE./ CHI.OR INATPn PESTICIDE PCB'SANALYSIS/ HE FOR THE FIRST TIME IDENTIFIED IN THE BODIES OF FISH. Monsanto and others began immediately to study the Swedish work. But, BEFORE THESE FINDINGS COULD BE CONFIRMED OR DUPLICATED IN THE U.S., . PCB'SANALYTICAL METHODS HAD TO BE REFINED IN ORDER TO SEPARATE FROM DDT)THE OTHER CHLORINATED HYDROCARBONS (LIKE THAT WERE KNOWN TO BE PRESENT IN THE ENVIRONMENT. NEW TECHNIQUES ALSO HAD TO BE DEVELOPED TO ENABLE RESEARCHERS TO IDENTIFY THE CHEMICALS IN THE LOW PARTS PER BILLION RANGES BEING REPORTED. Yusho Incident I 1968/ 1/000n about people in Japan became ill from eating rice oil PCB'heavily contaminated with Japanese produced s as a result of an UNFORTUNATE INDUSTRIAL ACCIDENT, THIS HAS COME TO BE KNOWN AS THE T PCB"Yusho Incident," he level of contamination in the rice oil was 2/000-3/000 PARTS PER MILLION/ EXTREMELY HIGH CONCENTRATIONS. (FOR. COMPARISON/ LEVELS BEING REPORTED TODAY IN FISH AND WILDLIFE ARE IN THE LOW PPM AND PPB RANGE.) (PPB EXAMPLE) Some news accounts linked this incident with deaths, stillbirths and MISCARRIAGES, WHILE/ IN FACT/ NO SUCH CASES WERE ACTUALLY ATTRIBUTED PCBTO THE INCIDENT. PERSONS EXPOSED TO CONTAMINATED RICE OIL DID EXPERIENCE DIZZINESS/ NAUSEA/ LOSS OF APPETITE/WEAKNESS AND DERMATOLOGICAL SIDE EFEECTS, INFANTS/ BORN TO MOTHERS WHO HAD BEEN EXPOSED DURING PREGNANCY/ EXHIBITED DARKENED SKIN AT BIRTH; HOWEVER/ IN EVERY CASE/ THIS CONDITION CLEARED WITHIN THREE WEEKS MAE 010250 STLCOPCB4031259 Pace 7 The victims: of the Yusho Incident have been subjected to extensive FOLLOW-UP MEDICAL STUDIES SINCE THE EVENT TO EVALUATE POSSIBLE LONG TERM chronic effects of the exposure, Some long-term chronic health EFFECTS WERE OBSERVED IN THE YuSHO PATIENTS, INCLUDING CANCER, HOWEVER, PCB'SRESULTS OF THESE INVESTIGATIONS INDICATE THAT PER SE MAY UGI HAVE BEEN THE CULPRIT IN THE YUSHO INCIDENT, OTHER ORGANIC CONTAMINANTS KNOWN TO BE SIGNIFICANTLY MORE TOXIC THAN PCB'S HAVE BEEN FOUND IN PATIENTS AT HIGH CONCENTRATIONS AND IN JAPANESE MANUFACTURED PCB'S, Some medical researchers and scientists are now unwilling,to blame PCB'S FOR CHRONIC EFFECTS OBSERVED IN THE YUSHO INCIDENT, ESPECIALLY IN LIGHT OF SEVERAL HUMAN EPIDEMIOLOGY STUDIES NOW AVAILABLE RELATED TO PCB EXPOSURE. Although conclusions about that incident have been clouded by the UNKNOWN IMPACT OF IMPURITIES IN JAPANESE MADE PCB'S, THE INCIDENT SOUNDED A CAUTIONARY SIGNAL. .` U.S. Concerns I 1970,n when These scientific investigations first confirmed the PRESENCE OF PCB'S IN THE ENVIRONMENT IN THE U.S. AND LONG BEFORE INFORMATION REGARDING THE POTENTIAL IMPACT OF THIS CONTAMINATION WAS DETERMINED* MONSANTO* WORKING WITH VARIOUS AFFECTED INDUSTRY SEG MENTS AND GOVERNMENT AGENCIES* VOLUNTARILY BEGAN ITS PROGRAM OF TERMINATING SALES OF PCB'S FOR OPEN APPLICATIONS -- THOSE WHICH COULD LIKELY RESULT IN UNCONTROLLABLE ENTRY INTO THE ENVIRONMENT. However, termination of sales for dielectric uses would have resulted IN SEVERE ECONOMIC AND SOCIAL PROBLEMS FOR THE NATION, THIS WAS PCB'SRECOGNIZED BY THE FEDERAL INTERDEPARTMENTAL TASK FORCE ON WHICH CONCLUDED IN 1972 THAT! ,,AE 01025l STLCOPCB4031260 Page 8 "Their continued use for transformers and capacitors in the near FUTURE IS CONSIDERED NECESSARY BECAUSE OF THE SIGNIFICANTLY INCREASED RISK OF FIRE AND EXPLOSION AND THE DISRUPTION OF ELECTRICAL SERVICE PCBWHICH WOULD RESULT FROM A BAN ON USE," At this TIME/ Monsanto made the conscious decision to continue supply PCB'sing QHLYTOTHE electrical power distribution industry where they WERE MARKETED AS DIELECTRIC FLUIDS IN "CLOSED" OR SEALED SYSTEMS SUCH AS TRANSFORMERS AND CAPACITORS, In CONTINUING THESE SALES/ MONSANTO REQUIRED CUSTOMER ASSURANCES THAT THE MATERIALS WOULD BE SAFELY HANDLED AND PROPERLY DISPOSED, MONSANTO/ THE GOVERNMENT AND THE ELECTRICAL INDUSTRY TOGETHER CONCLUDED PCBTHAT THE BENEFITS TO SOCIETY OF CONTINUED DIELECTRIC USE IN ENCLOSED ELECTRICAL UNITS FAR OUTWEIGHED THE RISKS, THE KEY TO MANAG ING THE RISK WAS SOUND MAINTENANCE PRACTICE AND DISPOSAL CONTROL. I 1977/ PCB'n sMonsanto voluntarily ceased all production of once we HAD BEEN ASSURED BY THE ELECTRICAL POWER INDUSTRY THAT SUITABLE SUBSTITUTES WERE AVAILABLE, ENVIRONMENTAL EFFECTS PCB's ARE STABLE; THEY RESIST DEGRADATION IN THE ENVIRONMENT AND AsPERSIST FOR LONG PERIODS OF TIME. THEY PERSIST/ THEY TEND TO ACCUMULATE IN ANIMALS AS THEY MOVE UP THE FOOD CHAIN. LOWER ANIMAL FORMS CONSUME THEM AND IN TURN ARE CONSUMED BY HIGHER FORMS AND/ IN SOME CASES/ PCB'S MAY ULTIMATELY REACH HUMANS VIA THE FOOD CHAIN, MAE 010252 STLCOPCB4031261 Page 9 PCBThe impact of contamination on ecological systems is not fully t _r. ____ UNDERSTOOD. . HOWEVER, THERE HAVE BEEN A NUMBER OF ATTEMPTS TO SUM MARIZE APPARENT EFFECTS AND TO ESTIMATE POSSIBLE FUTURE IMPACTS. PCB'S HAVE BECOME WIDESPREAD THROUGH CERTAIN NATURAL AND MAN-MADE MECHANISMS AND ARE OFTEN FOUND AT VARIOUS LEVELS AND LOCATIONS IN THE SOIL; AIR AND WATER. PCB CONTAMINATION IN URBAN AIR HAS BEEN REPORTED. ALSO, SOME U.S. PCBWATERS AND SEDIMENTS SHOW CONTAMINATION. i PCB'S ARE FOUND AT VARIOUS LEVELS IN ANIMAL AND AQUATIC SPECIES. ONE STUDY CONDUCTED BETWEEN 1970 AND 1974 BY THE U.S. FlSH AND WILDLIFE PCBCommission showed residues in various freshwater fish, waterfowl AND STARLINGS. A 1972-1974 STUDY OF THREE LAKE MICHIGAN FISH SPECIES TAKEN IN THE EASTERN PART OF THE LAKE SHOWED MEAN WHOLE FISH CONCEN TRATIONS RANGING FROM 5.24 TO 22.9 PPM IN BLOATERS;..SALMON AND LAKE TROUT. (1979-1980) PCBMore recent studies in the Great Lakes indicate that LEVELS IN FISH ARE NOW DECREASING. SIMILAR REPORTS HAVE BEEN MADE FOR FISH IN OTHER PARTS OF THE COUNTRY. PCB'S HAVE BEEN FOUND IN THE GENERAL U.S. POPULATION. SAMPLES OF HUMAN ADIPOSE TISSUE AND MILK., COLLECTED IN 1973 AND 1974 IN A NATIONAL SURVEY, SHOWED THAT 35.11 AND 40.3Z OF THE SAMPLES, RESPECTIVELY, CONTAINED 1 PPM OR MORE PCB'S ON A WETWEIGHT BASIS; ABOUT 5.OX OF EACH STUDY SHOWED GREATER THAN 2 PPM PCB'S. MAE 010253 STLCOPCB4031262 Page 10 HEALTH CONCERNS : Questions have been raised in four areas of possible health effects of PCB's: (a) skin (reddening, rashes, chloracne) (b) systemic effects (liver damage, respiratory effects) ` (c) WORKER EXPOSURE (d) carcinogenicity In the classical short-term exposure_qr acute toxlcjty sense, PCB's ARE CLASSIFIED AS "SLIGHTLY TOXIC" BY ORAL INGESTION, LD5Q 4,000-8,000 0SHAmg/kg (similar to NaCl-salt). For inhalation, has established SAFE EXPOSURE LEVELS FOR WORKERS EXPOSED TO PCB'S, (The EIGHT-HOUR TIME-WEIGHTED AVERAGE THRESHOLD LIMIT VALUES (TLV) FOR WORKER EXPOSURE ARE 1,0 (42Z CHLORINE) TO 0,5 (54Z CHLORINE) MG/M*.) Sm t Longer-term studies on skin effects using laboratory animals have SHOWN THE FOLLOWING! (a) Repeated and prolonged skin contact with the higher chlorinated BIPHENYLS CAN PRODUCE SKIN IRRITATION, (b) Harmful amounts can be absorbed under repeated, prolonged CONDITIONS, SUCH AS BY WEARING LEATHER GOODS THAT HAVE BECOME SATURATED WITH PCB'S, A PCB(C) SAFE EXPOSURE LEVEL DOES EXIST FOR EACH MATERIAL (i.E., A NO-EFFECT LEVEL), In addition, studies in 218 human volunteers using the patch test TECHNIQUE OF THE U,S, PUBLIC HEALTH SERVICE CONCLUDED THAT AROCLOR MAE 010254 STLCOPCB4031263 Page 11 (PCB) "...HAS NO PRIMARY IRRITANT EFFECT NOR IS IT A SENSITIZER OF HIGH POTENCY...,(MONSANTO RECORDS SHOW THAT THIS STUDY USED Aroclor 1254.) Human exposure studies also indicate that skin effects are reversible ONCE THE SOURCE IS REMOVED. * INHALATIQN/ReSPIRATQRY STUD IES Several animal tests have been performed to study the effects of LONG-TERM INHALATION EXPOSURE TO PCB'S. In SOME CASES IT WAS NECESSARY TO HEAT THE PCB'S IN ORDER TO OBTAIN THE HIGHER CONCENTRATIONS NECESSARY TO CONDUCT tHE EXPERIMENTS. PCB'Various s were studied at test chamber concentrations of about 1-6 PPM. No INJURY WAS OBSERVED AFTER PROLONGED INTERMITTENT EXPOSURE OF SEVERAL ANIMAL SPECIES AT THESE CHAMBER CONCENTRATIONS USING THE LOWER CHLORINATED PCB'S (i.E., 42Z Cl). At_.COMPARABLE._TSJ CHAMBER CONCEN TRATIONS OF THE HIGHER CHLORINATED PCB'S (E.G., SkX Cl) SIGNS OF REVERSIBLE LIVER CELL INJURY WERE APPARENT. Partly, as a result of these studies the American Congress of Govern (ACGIH) TLV mment Industrial Hygienists standards were established OSHA (1.0WERE subsequently incorporated into current STANDARDS AND 0.5 mg/m^), ' MAE 010255 STLCOPCB4031264 Page 12 Worker Exposure/Epidemiology ; PCB'The health effects of long-term human exposure to s have been . CAREFULLY REVIEWED BY SEVERAL RESEARCH GROUPS. MONSANTO IS AWARE OF U.S.SEVEN EPIDEMIOLOGICAL STUDIES DONE IN THE OF GROUPS OF PEOPLE PCB's.exposed to These included persons with occupational, as well AS COMMUNITY, EXPOSURE. The POTENTIAL HEALTH EFFECTS STUDIES INCLUDED DEVIATIONS IN BIOLOGICAL PARAMETERS (SUCH AS BLOOD AND TISSUE LEVELS) IAND REPORTED SYMPTOMS AND ILLNESSES. n ADDITION, THE CAUSES OF ANY DEATHS OF ANY PERSONS FROM THE SAMPLE POPULATION WERE INVESTIGATED. The four most recent studies appear to constitute the most extensive EPIDEMIOLOGICAL WORK YET DONE ON PCB'S. In total, the human epidemiology experience indicates an absence of MORBIDITY ' (ILL HEALTH) ASSOCIATED WITH SIGNIFICANT EXPOSURE TO PCB's. PCB'More importantly, none of these studies found s to cause cancer in humans, Potential Carcinogenicity - Animal Studies What about cancer in animals? In 1975, Dr. Renate Kimbrough reported THE INDUCTION OF LIVER CARCINOMAS IN FEMALE RATS FED AROCLOR 1260, A PCB, FOR TWO YEARS. Monsanto Company had sponsored previously three 2-year rat feeding STUDIES USING THREE DIFFERENT ArOCLOR-MIXTURES, INCLUDING THE SAME LOT OF AROCLOR 1260 USED BY Dr. KIMBROUGH. THE RESULTS FROM THE Monsanto studies showed that the test compounds produced liver injury BUT HQ CANCER. MAE 0L0256 STLCOPCB4031265 Page 13 An extensive re-evaluation by independent consultants was made of the LIVER TISSUE-SPECIMENS FROM THE MONSANTO SPONSORED STUDIES. In ADDITION/ SPECIMENS OF LIVER TISSUE FROM Dr. KIMBROUGH'S STUDY WERE ALSO EVALUATED BY INDEPENDENT CANCER RESEARCH EXPERTS. THAT REVIEW FAILED TO CONFIRM THE KIMBROUGH FINDINGS. IN OTHER WORDS/ IT SHOWED NO OCCURRENCE OF LIVER CANCER IN ANY OF THE FOUR STUDIES. In 1977/ the National Cancer Institute reported their results of yet PCB'SANOTHER INDEPENDENT STUDY FOR POSSIBLE CARCINOGENICITY OF (ArOCLOR 125*1) USING RATS IN A 2-YEAR FEEDING STUDY. THE NCI REPORT STATED THAT AROCLOR 125*1 WAS NOT A CARCINOGEN UNDER THE TEST 4 CONDITIONS. SUmARY/CONCLUSIONS . PCB'S HAVE BECOME AN INTENSELY EMOTIONAL ISSUE. IMPORTANT DECISIONS AFFECTING THEIR USE/ STORAGE AND ULTIMATE DISPOSAL ARE BEING MADE WITHOUT BENEFIT OF PROPER SCIENTIFIC ASSESSMENT, PCB'S WERE USED AS THE SYMBOLIC EXAMPLE OF WHY THIS NATION NEEDED TOUGH/ NEW REGULATIONS TO CONTROL TOXIC SUBSTANCES, IN THE PROCESS/ THE HAZARDS OF PCB'S WERE GREATLY EXAGGERATED! IN SOME CASES/ THESE COMPOUNDS HAVE BEEN LABELLED BY REGULATORY AGEN CIES/ LEGISLATIVE BODIES/ THE POPULACE AND THE MEDIA AS HUMAN "CANCER-CAUSING AGENTS" AND "DEADLY TOXINS," HOWEVER/ THE SCIENTIFIC EVIDENCE DOES NOT SUPPORT THESE CLAIMS. MAE 010257 STLCOPCB4031266