Document DvDoNyDVjQ88DQ6BEv6EEgXGN

Testimony on the PROPOSED STANDARD FOR VINYL CHLORIDE Presented by THE DON CHEMICAL COMPANY AT THE PUBLIC HEARING ON VINYL CHLORIDE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION DEPARTMENT OF LABOR WASHINGTON, D.C. June 25, 197A B + .fi,i ^' V" : 'S''- \ E'l-*' ' S-Ufr-, iv r if ? R*S 021182 INTRODUCTION t V. K. Rowe The Dow Chemical Company Midland, Michigan R&S 021183 INTRODUCTION I am V, K. Rowe, Director of Toxicological Affairs in Health and Environmental Research for Dow Chemical U.S.A, I RECEIVED a BATCHELORS DEGREE WITH MAJORS IN CHEMISTRY AND BIOLOGY IN 1936, A ^ASTERS OF SCIENCE DEGREE WITH A MAJOR IN BIOCHEMISTRY FROM THE STATE UNIVERSITY OF IOWA in 1937 and an Honorary Doctor of Science degree from Cornell College in 1971. i A, * > 71 I joined the Biochemical Research Laboratory of The How Chemical Company in the fall of T937 and have remained WITH THE COMPANY THROUGHOUT MY CAREER. In the fall of 1973, I was named a Research Scientist AND GIVEN MY PRESENT JOB TITLE. I am a Charter Member of the Society of Toxicology, and SERVED AS ITS PRESIDENT DURING THE YEAR 1966-67. I AM CERTIFIED BY THE AMERICAN BOARD OF INDUSTRIAL HYGIENE IN the Toxicological Aspects of Industrial Hygiene and served as President of the American Academy of Industrial Hygiene THIS PAST YEAR. I HAVE AUTHORED OR COAUTHORED OVER 70 SCIENIlFIC PUBLICATIONS AND FIVE CHAPTERS OF A TEXT BOOK ON INDUSTRIAL TOXICOLOGY. R&S 021184 I I HAVE BEEN ACTIVE THROUGHOUT MV ENTIRE CAREER IN THE AREA OF INDUSTRIAL TOXICOLOGY, INDUSTRIAL HYGIENE AND SAFETY EVALUATION. Throughout these years I have seen dramatic changes in THE DEGREE OF COMPREHENSIVENESS WITH WHICH TOXICOLOGICAL INDUSTRIAL HYGIENE AND MEDICAL SURVEILLANCE STUDIES HAVE BEEN AND ARE BEING CONDUCTED. THE TECHNOLOGIES USED IN THE 1930'S AND 1940'S WERE CRUDE WITH RESPECT TO THOSE USED IN THE 1950's -AND EARLY 1960/S BUT IT MUST BE REMEMBERED THAT THEY WERE THE BEST AVAILABLE AT THE TIME. 1960'Likewise, those used in the late s and now, are more COMPREHENSIVE THAN THOSE OF TEN YEARS AGO. I WILL BE AMAZED IF IN 1980 THE SAME CANNOT BE SAID OF THE TECHNOLOGY IN USE TODAY. THE SAME COMPARISONS APPLY TO ENGINEERING CAPABILITIES AND PRACTICES; PRODUCTION PLANTS AND PROCESSING PROCEDURES ENGINEERED TODAY BEAR R&S 021186 -4- ONLY A RESEMBLANCE TO THOSE ENGINEERED AND BUILT AS LITTLE AS A DECADE AGO. V.'KY AM I TAKING THE TIME TO MAKE THIS POINT? I WANT TO EMPHASIZE THAT THESE CHANGES REPRESENT PROGRESS MADE THROUGH RESEARCH AND I BELIEVE THAT THE VINYL CHLORIDE PROBLEM WE HAVE TODAY WILL BE SOLVED BY RESEARCH, NEW DISCOVERY AND THE APPLICATION OF the Rule of Reason. U ANDp until very recently when the toxicologists ONCOLOGISTS BEGAN TO ATTACH MUCH GREATER SIGNIFICANCE TO THE OVERALL CANCER PROBLEM, TYPICAL INHALATION TOXICOLOGY STUDIES, WHETHER DONE BY GOVERNMENT, INDUSTRY, OR ACADEMIA, CONSISTED OF EXPOSING RELATIVELY SMALL GROUPS OF ANIMALS FOUR TO SEVEN H0!JRS/DAY, 5 DAYS/WEEK FOR A FEW WEEKS, OR AT MOST, FOR A FEW MONTHS, The purpose was to find the maximum CONCENTRATION THAT DID NOT CAUSE A DISCERNIBLE EFFECT AND TO CHARACTERIZE THE EFFECT AT HIGHER LEVELS. SUCH DATA, WHEN AVAILABLE, WERE USED IN THE GUIDELINES FOR PERMISSIBLE INDUSTRIAL EXPOSURE. IT WAS TO SUCH A TF.STING PROGRAM THAT WE SUBJECTED VINYL CHLORIDE IN 1960, THE RESULTS OF WHICH WERE PUBLISHED IN 1961. Even though these studies on vinyl chloride were of longer DURATION THAN ANY OTHERS, THEY WERE STILL OF TOO SHORT A DURATION TO PERMIT DETECTION OF CARCINOGENICITY. THEY DID, HOWEVER, GIVE US A USEFUL INDICATION OF SIMPLE TOXICITY WHICH HELPED TO CAUSE US TO EXERT A POSITIVE EFFORT TOWARD REDUCING THE INTENSITY OF EXPOSURE WITHIN OUR OPERATING UNITS. R&S 021187 ft L J "Is?* ft e-J* ' R&S 021188 MAKE THIS POINT BECAUSE I HEAR COMMENTS TO THE EFFECT THAT THE DEFINITIVE STUDIES SUCH AS PpOp . '`'ALTON I AND THE MCA ARE CONDUCTING NOW SHOULD HAVE: BEEN CONDUCTED YEARS AGO. It IS TRUE THAT IT WOULD HAVE BEEN GREAT 1 JF SOMEONE HAD CONDUCTED SUCH STUDIES YEARS AGO, BUT NO t ONE, TO MY KNOWLEDGE , EVEN SUSPECTED VINYL CHLORIDE OF BEING A CARCINOGEN. HENCE, IT WOULD HAVE BEEN DIFFICULT TO JUSTIFY THE USE OF THE LIMITED RESOURCES A7AILABL STUDIES FOR VINYl CHLORIDE Furthermore, DOUBT THAT ROF. u IES WOULD HAVE BEEN INITIATED WHEN THEY WERE IF IT HAD NOT BEEN FOR THE SERENDIPITOUS DISCOVERY BY PROF. VlOLA OF TUMORS IN THE RATS IN WHICH HE WAS ATTEMPTING TO INDUCE THE LIKENESS OF HUMAN ACROOSTEOLYSIS. r 1 DO FEEL, HOWEVER, THAT THE VlN'L CHLO" 1 UE *-- .i * *'i* *i * t% TAUGHT IJG ALL A LESSON THAT WILL, III THF LONG RIJN, I'D much to develop an awareness that will lead m atiirs OCCiPAT ! ONAL AND ENV I RONM.F.NTAL HEALTH 4 R&S 021189 I FEEL THAT IT IS EASY TO OVERREACT TO SITUATIONS SUCH AS THE VINYL CHLORIDE PROBLEM AND MUCH MORE DIFFICULT TO S"E= BACK, OBJECTIVELY ASSESS THE SITUATION AND DEVELOP A COURSE OF ACTION THAT TAKES INTO CONSIDERATION THE REASONABLY EXPECTED CONSEQUENCES OF THAT ACTION. ! BELIEVE THAT the Emergency Temporary Standard was a good example of THE LATTER TYPE OF ACTION FOR IT FOLLOV.'ED THE RULE OF KEASQN . R&S 021190 The How Chemical Company, from top management down,- is DEEPLY CONCERNED ABOUT THE HAZARDS TO HEALTH PRESENTED BY EXPOSURE TO VINYL CHLORIDE, AS WELL AS OTHER SUBSTANCES, DOW HAS BEEN IN THE FOREFRONT IN ITS CONCERNS ABOUT THE TOXICOLOGICAL HAZARDS PRESENTED BY THE MATERIALS IT USES, MANUFACTURES AND SELLS. Urf.K -0- This is attested to by the fact that Dow supports TOXICOLOGICAL RESi.*L G1' LAEORATOR I ES IN MIDLAND, mICh.GAN, Freeport, Texas and zionsville, Indiana employinc a total OF 12^ PERSONS, 25 OF WHOM HAVE DOCTORATE DEGREES. ITS INDUSTRIAL HYGIENE LABORATORIES ARE STAFFED WITH OVER TWENTY INDUSTRIAL HYGIENISTS SUPPORTED BY A NUMBER OF ANALYTICAL SPECIALISTS. ) ,'S MEDICAL FACILITIES AT Midland, Michigan and Freeport, Texas are extensive; THE STAFFS CONSIST OF BETWEEN 70 AND 85 PERSONS, 11 OF WHOM ARE FULLTIME PHYSICIANS. ThE SMALLER PLmNTS ARE * ALL SERVED BY PART-TIME PHYSICIANS AND FULLTIME STAFFS UNDER THE SUPERVISION OF THE PHYSICIANS OF OIJR CORPORATE MEDICAL DEPARTMENT. R&S 021191 t ****> ; *'' `t v H ft. W aM? |4:*? & m%- &; TO THOSE CHARGED WITH THE RESPONSIBILITY OF WEIGHING RISK VERSUS BENEFIT WITHIN THE CONCEPT OF THE RULE OF Reason. We WILL PRESENT TESTIMONY DEALING WITH ENGINEERING PRACTICES. INDUSTRIAL HYGIENE MEASUREMENTS. PERSONAL PROTECTIVE DEVICES, MEDICAL SURVEILLANCE, MEDICAL OBSERVATION BASED ON A STUDY OF MORTALITY AND A PROGRESS REPORT ON RESEARCH INTO THE POSSIBLE MECHANISM OF ACTION OF VINYL CHLORIDE. It IS OUR PLAN TO HAVE THOSE MOST FAMILIAR WITH THE VARIOUS ASPECTS TO MAKE THESE PRESENTATIONS Afc- R&S 027192 r &S 021193 11- - Now, I SHOULD LIKE TO INTRODUCE Mr . KARL OELFKE, PRODUCTION Manager of vinyl chloride who will discuss our experiences RELATIVE TO THE RELATIONSHIP BETWEEN ENGINEERING, WORK PRACTICE AND MONITORING IN THE REDUCTION OF THE RELEASE OF VINYL CHLORIDE AND CONCOMITANTLY THE REDUCTION IN THE OPPORTUNITY FOR EXPOSURE OF PERSONS TO THE VAPOR. * r &S 021194 ENGINEERING AND CONTROL PRACTICES " K, H, Oelfke . The Dow Chemical Company Freeport, Texas -1- Good morning, my name is Karl Oolfke. I am Production Manager at the Texas Division of Dow chemical U.S.A. My area of responsibility includes the manufacture of vinyl chloride at the Texas Division. In addition, I am responsible for the coordination of vinyl chloride production techniques and technology for The Dow Chemical Company on a world-wide basis. R&S 021195 i *1 I would like to speak on Engineering Controls and Manufacturing Practices in both the production of vinyl chloride monomer at our three United States manufacturing sites and the copolymerization of vinyl chloride monomer at our manufacturing site in Midland, Michigan. The first part concerns vinyl chloride monomer (VCM) manufacture. This is an aerial view of our oldest currently operating VCM plant in our Texas Division at Freeport, Texas. Commercial scale production of vinyl chloride was started here in 1948. Over the years, through what we have called incremental expansions, production capabilities have been increased by some 400%. You will notice that there is little separation of equipment and the close proximity of the control room to the processing area. The control room is at the middle left of the picture. t rv* ' `V R&S 021196 2- - You can get some idea of the size of t'c plant by noting the sizes of the cars in the photo. Our second monomer plant came on stream in 1958 and is located in our Louisiana Division at Plaquemine, Louisiana. This plant has been incrementally expanded over the years and production capabilities have been increased by some 1,000%. Again, as a result of these expansions, you will note the congestion of equipment, but you will please also note the congestion is less than that shown on the previous slide. Here we have our most recent vinyl chloride monomer plant located in our Oyster Creek Division at Freeport, Texas, and started in 1969. The most recent plant layout criterion was used at this plant and congestion is minimal. Here the control center is located at an increased distance from the process area. I'm sure that if we were to design another vinyl chloride plant today, even more thought would be given to plant layout and design. In earlier years, more concern had been for the hazards of fire and explosion of vinyl chloride. These hazards were the main causes for greater separation of equipment. Typical of this concern is illustrated by flammable gas detector L.V*** ' Mr -Jr' .1-,. alarms which are strategically placed in the plants to alert personnel in the event of a major leak or spill. One other thing you might have noted is the trend in recent years toward large single "train" units rather than several smaller "trains." Economically, this can be shown by the generalized formula that indicates that the capital requirements for a plant twice as large as the base unit is 2 to the .6 power. Thus, for 2 small plants, the capital required would be 2 x the base unit, but for a plant twice as large as the base would only cost 1.52 x the base unit. Capital abandonment of an existing plant in favor of a new facility of the same size and essentially the same technology is generally not done ic the industry. Economics do influence this decision, such as the reduction in cost of manufacturing as the result of decreased maintenance cost, improved manpower, utilization, improved raw yields and lower freight costs. From a health standpoint, these large single "train" units considerably reduce emissions because of the fewer number of pieces of equipment. 30 fi (A Oro to _ f\ ^ were high :;i.unlenancc items, there- was no way to eeonon i-ca 1 1 y justify replacement by a centrifugal compressor . Potcsn.t i a i leak:', are- reduced tunny told using centrifugal., in'.t- 'i'l reciprocating. F. 1 i mi na t i on of tin.- compression st-p in ;h" best soh:tJon and this-: ha:; been ncoomp 1 i savd ltt our most i* 11 plant . 3> (/> TO <0 (0 Okay, new plant design and. construction ban the pot-Uit i ii f'a s if; n i f i car, 11 y reducin') vinyl chlorine exposures tit the work place through such things as plant layout and cleotnat mn <d equipment- However, :d the pictures you nave seen tit.it tin- plants are large and complex with many valve:-;, pumps, and flanges. Consequently, the complete elimination o: leak:.; f.-en in a foreseeable new plant is not technically feasible. What can be done using any i r.eer i :iy; control and: workplace practices to reduce emissions in existing vinyl chloride monopier plants? First, I would like to emphusi ;:o that, esser.ti ,1 to engineering controls and workplace practices is the ident i f nv.t ion of problems through workplace monitorin'). This can be nccompi ished by analyzing grab samples of air from various locations, by usim; personnel monitoring techniques based, on carbon adsorption, carbon disulfide extraction and gas chromatography, and lay area monitoring. Using these techniques, problem areas were ident i * ioe. . To illustrate what can be done, I will now describe several of * -9- these problem ui'ca:; and the onq i ru'or i nq and work ; >r. i<: 1.1 ia methods used to ri.'duco cm iss ion:;. t r- R&S 021200 Tank Car beadino " * t has been i ndustr i a 1 praot ice for many years to gauge tank car innaqe on pressure c irs u:. i nq vented slip tube:; as shown in-re. The level of the liquid in tintank car is deter::) i nod by obsu rv: nq for liquid or qua ! 1 ow from thin tube. Frciqht bills arc based on weights of products shipped. Pressure car minimum rat.es are calculated I111' v8> of allowable. For this reason, we want to fill tank cars between 98 and lOOi of allowable. These gauging devices areset when the tempo-rat.are of the vinyl chloride inside the tank car has been determined.. Form illy they are set at `Mb of allowable so that when the car has beon filled to that level, the loading person can see that the loading is almost finished as the vinyl chloride liquid spewing from the opening create:; a short--1 ived fog (hut an emission, and potential expos',..: e point > . He then re,adjusts the slip tube t.o 98' level and t^-ps o:: tine tank car. Ever, though the- 8-hour TWA was Lei-w 90 ppm as determined by personnel monitoring, steps are bemq taken to eliminate this emission. For the long-term solution, magnetic gauging devices are being secured and installed. It is estimated that all of the vinyl chloride tank cars that Dow fills will bo equipped with this type gauging device by the end of 1975. An interim solution is being sought at this time. Tests are being conducted using a temperature sensing device in a closed loop system. This device has had limited testing, hut it loo'/.s very promising. Disconnecting loading and vent lines from tank cars was another exposure problem. The exposure potential has been lessened through purging the liquid and vapor lines into the tank car with nitrogen. In-Plant Sampling - Process and quality control samples are a must in the vast majority of chemical production plants. On stream analyzers are the preferred method if at all possible. In some analyses, on stream analytical technology has not been developed. Sampling of the process streams has to be done. Again, with personnel monitoring as our guide, these problem areas were brought to our attention. This is a picture of the old method, the picture was posed. Here we see a closed loop sampling system developed to decrease potential personnel exposure. Doth cylinders are evacuated at the laboratory. (The vacuum pump vents to a hood stack.) 3J fi (/> o N> ro o The sample cylinder is at the bottom, the waste cylinder is at the side. Vinyl is purged from the liquid line at the top, through the cross and out the flexible line at the left. The flexible line is closed and the sample cylinder filled. The valves are blocked from the liquid line and at the cylinder. Prior to disconnection, the waste cylinder (under vacuum) is opened to evacuate the sample header. Considerable potential '' - exposure was eliminated. fe":; ri- * -f !**( tr*f" $$ ICt^Vi Sf "tn# *.'? r tfi ^- <Analytical - Personnel monitoring results of our laboratory .''personnel caused us to study more in depth the job make-up. Wet methods of analysis at one time were performed in the laboratory, but outside the hood. As a result of the moni toring, these analyses are now performed under the hood. Further monitoring indicated that this method of transfer was not satisfactory (hood door raised), although better than previously experienced. This is the method we now use (hood door closed). Unused sample portions are returned to the process. As we worked on our areas, even though exposures were not necessarily being experienced (they probably were) other problem areas were seen. In-plant - Header systems such as this pump drain line, rcboilcdrain line, and vapor recovery units are being installed to return vinyl chloride containing streams to process when main tenance work must be performed. At present, only that equipment requiring frequent maintenance is so headered, such as pumps, reboilers, and filters. Operating procedures were changed to require purging of liquids from lines using nitrogen prior to maintenance. As you have seen, engineering controls and workplace practices can reduce the potential exposures of our employees working in monomer production, but again I should emphasize that a monitoring system is essential to locate the problem areas. R&S 021202 What about vinyl chloride exposures in polymerization plants? What has Dow done to reduce the exposure potential? Our most recent polymerization plant in Midland, Michigan was constructed with separation and protection of the major processing phases in mind to minimize potential capital loss. The separation also tends to reduce the potential personnel exposures. Compare this most recent installation with the original plant. You will note the original plant was completely inside a building, while the newest plant utilizes more open construction, even though it is built in the cold North. Vinyl chloride is unloaded into a tank farm some distance from the processing area. The new polymerization areas are highly automated, using sophisticated computer equipment. The areas were designed and constructed to include: no precessing system open to the atmosphere; minimum monomer storage in the polymerization area; minimum number of monomer transfers; no routine opening of monomer lines; larger capacity equipment and a minimum number of vessel openings and entries. We are also testing canned or sealless pumps. The polymerization control rooms are pressurized with fresh air and are continuously monitored for vinyl chloride. sS-. r * R&S 021203 "j m: tt;- f P j rf>\ eV; .< V/}: Vf---: ir.. . i-4\-K," ' , - Mr L` 'Jtj, * }.' -10- Extensive inline or onstream instrumentation is used (this is a conductivity cell) to minimize the need for taking process samples containing vinyl chloride. Where monomer samples arcrequired, a closed loop system is used. Here the sample cylinder (still containing the residue from the last analysis) is connected to the liquid line on the left and to a vacuum line on the right. The valves are arranged to flow through the cylinder. The cylinder valves are closed as well as the sample point. The vacuum line is opened to the left end of the cylinder. This allows both ends of the cylinder to be evacuated prior to removing it. This is in contrast to past sampling procedures (this picture was posed). At the present time, even with the best designed system, it is occasionally necessary to open lines and equipment which have been in vinyl chloride service. In these cases, piping provisions have been made to allow draining the monomer, flushing with non-nazardous material and purging with an inert gas before opening to the atmosphere. In our polymerization plants, just as in our monomer plants, lower explosive limit alarms are located throughout the plant to detect major spills and leaks should they occur. As will be presented in our testimony on monitoring, we've R&S 021204 R&S 021205 come a long way in reducing vinyl chloride exposures of our employees through engineering techniques and workplace practices; and, as technology improves, we will further reduce these potential sources of exposures. However, from a practical standpoint, the technology does not now exist to eliminate all sources of emissions in those large complex plants. R&S 021206 R&S 021208 if $ I I R&S 021212 R&S 021214 & # R&S 021217 o 3 i r it ;= .t R&S 021224 I WOULD NOW LIKE TO INTRODUCE Mr. ROGER DANIEL, MANAGER of Industrial Hygiene for our Texas Division, Mr. Daniels WILL DISCUSS THE PRINCIPLES INVOLVED IN AREA AND PERSONNEL MONITORING AND THE SIGNIFICANCE OF SUCH DATA IN DESCRIBING THE EXPOSURES OR POTENTIAL EXPOSURES OF WORKMEN. He WILL ALSO DISCUSS THE USE OF VARIOUS MONITORING TECHNIQUES IN DETECTING UOBS WHERE PROTECTIVE DEVICES ARE NECESSARY, IN LOCATING SOURCES OF RELEASE OF VCM SO THAT PROMPT MAINTENANCE CAN BE INSTITUTED AND EXCAPE OF MATERIAL AVOIDED. Roger t ; i i MONITORING jj co o ro IS5 N) CJI R. L. Daniel The Dow Chemical Company Freeport* Texas 2- - .i MONITORING VINYL CHLORIDE LEVELS IN THE WORKPLACE My name is Roger L. Daniel. I received a UA degree in chemistry from Austin College and an MS degree in chemistry from Texas Technical University. After five years with Phillips Petroleum I joined The Dow Chemical Company in Texas in 1957 as an analytical chemist. I then went to the Chlorinated Hydrocarbon Lab in 19G0 and held various positions until my promotion to Department Manager in 1970. In 1972 I became Technical Manager of the Solvent, Technology Center; and, in 1973 was promoted to the present position of Manager of Environmental Health Services for the Texas Division. In this capacity, I am responsible for the design and implementation of industrial hygiene surveillance programs for all employees in the Texas Division of Dow Chemical. In the early history of the vinyl chloride industry, a chief concern from an employee safety standpoint was the flammability of this material. Instrumental methods in the field of analytical chemistry were in their infancy when vinyl chloride production in the United States passed the 100 million pound per year mark in the mid 1940's. The analytical methods available were of low sensitivity and offered little or no specificity. The belief that vinyl chloride was of relatively low toxicity provided little impetus for development of analytical methods suitable for measuring low levels of this material in the workplace. 3J w 0 NJ _L to to 01 n f r e t r 5 The increasing awareness of the chronic toxicity of many compounds paralleled the development of analytical instrumentation adaptable to continuous monitoring of process 9 -3- streams for, first, major components, and later, minor components. In my 22 years in the chemical industry I have witnessed the ultraviolet spectrophotometer develop from a simple laboratory tool to a process analyzer capable of providing data for control systems to optimize complex chemical processes. We have also seen a similar develop mental pattern in applications of infrared spectroscopy, mass spectroscopy, and gas chromatography. The degree of analytical sophistication is such that, it its commonplace to think of the determination of many organic compounds at the part per million level. On June 12 the hnvi ronmentn 1 i'rotectif.n Ag.-ncy released the results of recent surveys for vinyl chloride levels at the property line of vinyl chloride monomer and polymer production facilities. Values as low as thirty parts per billion were reported for samples collected on the Houston Ship Channel. This demonstrates the degree of soph i s t i ca t ion t.'iat has been achieved in ambient air monitoring. '4' * Equally important have been the strides made in the past thirty years in miniaturization.' Radios, television sets, cameras and electronic calculators are but a few of the things that come to mind in this area. Important progress has also been made in the miniaturization of the tools of the trade of the industrial hygienist so that sampling equipment can be totally mobile and self-contained. R&S 021227 The impetus has been provided, and the technology is available, so the nex4- step is to examine possible elements of a comprehensive vinyl chloride surveillance proqram and to tailor a program to fit the conditions in a particular facility.* S-l $ t\ y' &' $ -1- A continuous area monitoring system is an essential clement of a surveillance program for vinyl chloride monomer and polymer production facilities. Throe typos of information can be generated from such a system. Continuous area monitoring can provide information as to the vinyl chloride concentration at specific locations at a specific point in time. After some finite interval, sufficient data will be generated to permit a concentration profile to be calculated for each specific location. If the monitoring system is adequate in scope, a plant-wide average concentration profile can be calculated. Secondly, a continuous area monitor can produce a history of employee exposure. If an employee spent his workday only in the areas monitored and divided his time equally among these locations, the plant-wide average concentration would be equivalent to the employee's exposure. The above circumstance is idealistic and does not approximate the real world. However, if a weighted average concentration that considers the time spent in each area is calculated, this value will more nearly approximately the employee's exposure. Normal time distribution vs. plant location can be developed by studying the normal job activities of each individual or job classification. This method of deter mining an employee's exposure is most successful when the employee's routine varys little from day to day. A third and obvious value of a continuous monitoring system is that it provides the capability for early detection of leaks of vinyl chloride into the atmosphere. The flammability -o n JJ c/> o fO ro mf oo * 4-^a, f R&S 021229 -5- of vinyl chloride is recognized throughout the industry and plant facilities are usually well monitored with :<> flammable gas detectors. However, these detectors wouLd normally alarm only when vinyl chloride levels reached approximately 4000 ppm. If the continuous monitoring system is broad enough in scope and the sampling locations are F-. judiciously selected, the probability of leak detection before levels reach 50 ppm is high. The use of personnel monitors is the second element of a comprehensive vinyl chloride surveillance program. If the sampling device and analytical workup are properly designed, I samples collected on the employee's person will document his time-weighted average exposure for the duration of the sampling period. i One obvious shortcoming of this approach is that the level of an employee's exposure is known only after the fact. Secondly, this teennique, as stated earlier, produces a time- weighted average exposure value and, therefore, gives no indication of the maximum or minimum concentrations in the employee's work area. Finally, personnel monitors available; 1 today do not provide on-the-spot data and, therefore, offer no warning when the employee is in an area where concentra tions are above acceptable values. In addition to providing a documentation of the average exposure throughout the workday, personnel monitors provide a tool for evaluation of work practices and engineering controls. When time-weighted average exposure values approach the levels allowed by standards, the industrial hygienist will perform in-depth studies to determine whether or not specific job steps might account for the bulk of the employee's time-weighted average exposure. After identifying sources of exposure, cither something that is employee controllable, or something that is inherent in plant design, changes can be instituted. Follow-up personnel monitoring will provide data for evaluation of the effectiveness of the change. ---^ R&S 021230 Instrumentation and methodology of monitoring; have been dis cussed in detail in the SPI presentation no wo now turn our attention to the vinyl chloride levels in our monomer pro duction facilities. (Mont Slide) Table 1 shows a summary by job classification of employees exposure* to vinyl chloride. The 1971 values were calculated from numerous area samples and employee time distribution data. The method is slow, creates a heavy analytical load, and is questionable in that t' 'ndustrial hygienist is a constant companion to the employee during the sample collecting process. Never the 1 * *ss , the values fall in the range of those for subsequent, years which wore obtained using the personnel monitoring technique. Quality control work is performed. by the Senior Assistant Chemist B classification; jol.* dur ics include sampling and. analysis of the finished product, The analytical procedures require measuring, weighing, and titration of liquid vinyl chloride samples. The operations are carried out in a laboratory hood but some exposure does occur. Loading operators are another croup that have a high potential for short term exposure in that tank car loading operations, as performed traditionally, do release vinyl chloride to the atmosphere. We will discuss each of these operations in more detail later. The overall average was less than lOppm in each of the three years but in 1972 and 1973, at least one job classification had exposures greater than lOppm. (Next Slide) S-3 Table II contains personnel monitoring data for the first and second quarters of 1974. Again, the Senior Assistant Chemist B and the Loading Operator arc in the above average exposure group. The C Control--Section I also collects samples of vinyl chloride and, therefore, has a relatively high potential for exposure. The overall average.is of the same order of magni- R&S 021231 tudc as in previous years. The frequency of monitoring is now three to four times that in previous years. Wc mentioned earlier the utility of personnel monitoriny in evaluating job procedures and engineering controls. (Next Slide) Table III shows the results of short term sampling while specific operations are being performed. These data were collected during the second quarter and are in chronological order. The loading lines on tank cars must be cleaned of vinyl chlorioe prior to disconnecting if release of vinyl chloride to the atmosphere is to be avoided. The: solution involves both job procedure and engineering controls. At first glance, it appears the problem .is solved, but, the fifth data point exceeds the present permissible ceiling value and the sixth is at the upper 3init . Fresh air masks are being worn during all loading operations. Engineering controls quickly reduced one of the chief causes of the Senior Assistant Chemist B's exposure, that which occurred during the sampling of product tanks. Mr. Oelfke has described the closed loop sampling installations that arcused in all of our facilities. These data attest to the effectiveness of this approach. Area monitoring is presently being done by gas chromatography using a twelve point sampling system. Due to the complexity of operation in and adjacent to Monomer Plant No. 1, the cycle time per sample point is 15 minutes. We are presently augmenting the surveillance by daily grab sample monitoring in the close proximity of equipment that has a potential to release vinyl chloride. The final form of the ami monitoring system is yet to be defined. ' - --y'U 44s* e **1' I# >T &i x ^ '-. Sw. v.fc i . * - '-\A ,7 ' :?- r`. ;, . ;/ ' " WK' _ tij (., *V ** N1* 'A'?'. ?! 8- - Monomer Plant No. 2 traditionally has conducted an annual in-depth industrial hygiene survey for employee exposure to air contaminants. The summary of the 1973 and 1974 survey is shown in Table IV. (Next Slide) The organiza tion, and, therefore, job classification system, differs from those in Monomer Plant. No. 1 but it is obvious that lab personnel and loading operators are again the exposed classification. Loading operators at this facility are wearing fresh air masks while engineering controls are bei.ua developed. This facility is newer than Monomer Plant No. 1 and has, as a desgn feature, fewer sources of emission. The overall average exposures attest to the impact of improved design on employee exposure. This facility has had a ter. point area monitoring system in operation since late April. The cycle time is 6 minutes per sample point and the sensitivity is approximately O.lppm. (Next Slide) Data from the various locations are shown in Table V. The number of excursions that exceeded the full scale limit of the system are shown in parentheses. Less than One percent of the values are above llppm. Examination of the raw data showed that, corrective action had been taken within the hour and that the concentration was below lOppm the following hour. S-5 33 </> oro ro croo S-6 (Next Slide) Table VI contains time weighted average data for Monomer Plant No. 3. This is the newest of the three facili ties and employs the latest design technology. The overall average time weighted exposure at this facility is the lowest of the three. The problem areas are readily identified; these are the laboratory technician and the loading technician classifications. S-7 Peak exposure data in Table VII (Next Slide) show that the laboratory technician does fecoivo a part of his ovprjsure S-8 *r > -L-?r'i V'*"- * "W; -y-' ., during analysis of the product. The loading technicians exposures arc within pcrmissablo levels while disconnecting' tank cars, but we are still using fresh air masks for this operation. The low peak exposure data for the repair technician are attributable to the thorough purging iob that was done prior to opening the equipment for maintenance. 8 n An area monitoring system is on order for this facility am: equipment delivery is promised in mid-July. The sys t - n will be similar to that at Monomer Plant Mo. 1 both in cycl*- time and sensitivity. In our copolymer facility Dow has had a conprehonsiv vinyl chloride surveillance program since 1950. (Next Slide) This is a summary of the TWA exposures for the ten year period S-9 1950-59. The product produced is a copolymer of vinyl and vinylidcnc chloride, and, the air contaminant is a mixture of these two compounds rather than pure vinyl chloride. In the emissions, the relative ratios are'95 parts vinyl chloride and 15 parts vinylidono chloride. Darin,;; this period, t he vapors were adsorbed on silica gel and a total chloride- deter 30 </> oto --L ttoo CO mination made in the laboratory. The total chloride, calcu lated as vinyl chloride are shown on this slide. Note that TWA's as high as 385ppm and excursions as high as 4,000ppm were experienced. (Next Slide) Since 1960, a continuous S-10 area monitoring system has been in operation. This is a non specific analyzer based on the combustion-conductivity approach. These data are a summary of the TWA exposures for 1960-63. The drier operator had the highest TWA, 85ppm and the excur sions were now down to 500ppm compared to the 4,000ppm ex perienced in the 1950's. The TWA's were calculated based on the prcdcsignatcd time the operator normally spent in each area. 1- '.)- Continuous air analyses are still performed using the com bustion-conductivity analyzer. The output from the analyzei: is now computerized and a typical daily summary report is shown in the next slide. (Next Slide) There are 18 sample point locations; the cycle time per point is approximately 1/2 minute. The data are sunn.iraxed for each eight hour shift. The information includes the; number of samples taken at each location, the average of all samples, the maximum concentration at each location and the time at which the maximum occurred. Those data are then time-weighted, based cj; the predosignated time the operator normally spends in each area, to produce a TWA exposure distribution. (Next SIide) Again, the data are presented for each shift. The report shows the percent of the work day the employee spends at various exposure levels. Note the 591 polymer operator on the day shift where 81 percent of his time was in the 0-5ppm level and 3 percent was in the 25-50ppm range for an 8-hour average of 5.1 ppm. The analyzer is set to alarm at 25ppm; from the analyzer employees can determine the location of the problem. Appropriate respiratory protection is worn in the area while the problem is being corrected. (Next Slide) This is a summary of average exposures for February through May 1974 for the four job classifications shown on the previous daily report. These data show that levels can vary by a factor of three from month to month. Note also the shift to shift random variation. We have discussed the calculated TWA's from area monitoring. Now lets look at some recent personnel monitoring data. (Next slide) These data support the day-to-day variations observed by area monitoring. (Next slide; The packager operator has generally low exposure but still haci day-to-dav variations. S-14 S-J5 R&S 021234 r .J r-f m lfc'; a-- . 35; fc. M' Jlgk iv* <&A;'r''. ^K,(v., ;,V' V H( hwi i*{..--.*, k, hV- .? fee IPf;'.. &?VC- .* forX"V ..". r* ? i<\v\l ,,*, '* ; ii(|| Using charcoal adsorption tubes short term area samples wore collected to identify these operations which resulted in short term release of vinyl chloride to the atmosphere. (Next Slide) These data collected in the fall of 1073 showed that draining the filter and brine draining both resulted in significant release of vinyl chloride. Kngineering controls, described by Mr. Oelfko, eliminated ouch of these problems. An inert gas purge system is now used to clear the filter prior to change-out of the filter demerits. The brine system was repiped to recycle brine to the process. This has eliminated employee exposures from each of those sources. S-l G Short term samples using the personnel monitor are companion data to the area samples just discussed. (Next Slide) Note the short term l,800ppm of the breathing none sample collected during brine draining. The use of respirators were instigated until engineering controls were installed to eliminate this exposure. Engineering controls have been installed in the suspension production unit that has eliminated these sources of employee exposure. In the emulsion production unit all are corrected except the reactor washout. For that operation air supplied respirators arc required. Engineering studies arc underway to correct this situation. The final slide shows a comparison between 8-hour TWA's from personnel monitoring and calculated 8-hour TWA's from area monitoring for the Reactor Operator. The data show reasonably good agreement; note that computers do have downtime. The area monitoring system output is both recorded and alarmed independent of the computer so we are not dependent on the computer for area surveillance. S-17 ! k. i S-18 30 fia Cfl rOo ro co cn 1; '-SJ- ' rvr* We have attempted to show the Col lowing: (1) Area monitoring is desirable for leak detection purposes. The optimum instrumental on will vary from plant to plant. Only people familiar with the problems of the location should attempt to design an area surveillance: system. (2) Personnel monitoring is useful to establish what an employee's exposure has bcon--both on a short term and 8-hour day basis. (3) Backed up by personnel monitoring, calculated TWA's based on area monitoring data and time distribution studies can give a good indication of the level of exposure experienced daily by various job classification. (4) In modern engineered plants, with continuous area monitors air-borne levels can be minimized but not eliminated. 1 mm !< ' 'yy' Tr).-H- er a. v-:-