Document J3DpVdD7YGqRmMm2qmJqGGkb6

Exposure to Coal Tar Pitch Volatiles at Coke Ovens N. FANNICK,* L. T. GONSHOR, and J. SHOCKLEY, JR.t Pennsylvania Division of Occupational Health, 1875 New Hope Street, Norristown, Pennsylvania I9401 Personnel of the Pennsylvania Division of Occupational Health began surveying for exposure to coal tar pitch volatiles at coke ovens in 1966. A routine of sampling procedure and method of analysis has been developed, and ten coke oven installations have been surveyed. Approximately 320 samples were collected with fdters mounted in plastic holders attached to the workers' shirt collars, and an integrated sample of 3 to 6 hours was obtained. Samples were also collected at various futed locations. The results of these surveys have been compiled tu determine exposure levels of specific jobs and work situations The report indicates that all exposures are in excess of the threshold limit value. t htroduction i orkers on coke ovens are thought to have a higher incidence of lung cancer i lbpn the general population. This is alleged to be caused by exposure to polynuclear aromatic i hydrocarbon compounds, including coal tar pitch volatiles (CTPV), which are generated during the coking process.'-4 The American Conference of Governmental Industrial Hy*tS has established a threshold limit value Coal tar pitch volatiles (benzene-soluble `netion of total particulate) of 0.2 mg/m3 of ur* fQr an %hour daily exposure.' Pennsylvania is a center of the steel industry has eleven by-product coking facilities with of the nation's coking capacity.6 In 1966, WrWmel of Pennsylvania Department of h t h began working on methods to survey to analyze for CTPV. The sampling and *fiical methods and the initial findings have *- Published.' This report details the findof surveys at ten of the by-product coking f*uities in this state. OR-nt address: U.S. Department of Interior, *`gtOn* D.C. 20240. therent address: American Foundryrnen's so'%'Oes bines, Illinois 60016. Description of Operations Coke is a product of the destructive distillation of bituminous coal; it finds its major application in the production of steel. It is manufactured either by the beehive or by-product (retort) process. The beehive process is no longer used substantially in Pennsylvania and was not considered in this survey. A typical (by-product) coke oven is 10 to 15 feet high, 35 to 45 feet long, and approximately 18 inches wide. A hundred, or fewer ovens are generally assembled into a battery, and several batteries are combined into a coking facility. Each oven receives a charge of 10 to 18 tons of coal. Heat is applied to the walls of the ovens, and the volatiles are generated and conducted through pipework into a by-product recovery plant to be processed into xylene, toluene, etc. After a coking time of 16 to 20 hours, the coke is pushed through the oven into a quench car, emitting dense clouds which are principally dust. It is during the charging operation that workers are exposed to polynuclear aromatic hydrocarbons. Lesser sources of such exposure are the numerous cracks and leaks in the oven doors, charging ports, and standpipes. The following eleven job classifications (in- 46 1 ., ` . f i. ' ,.-, 462 cluding a miscellaneous category) are required in the operation of coke ovens and were studied in our surveys: Larry car operator: Fills the coal hoppers on the larry car by manipulating levers on a platform outside the car; drives the car into position above the charging ports; discharges coal into these ports by manipulating levers inside the cab; and adjusts the standpipe(s) by means of a long rod. These duties involve exposure both inside and out of the larry car cab, and at times, during charging, the operator is exposed for short periods to heavy concentrations of coal dust as well as effluent gases. Lidman: Opens the charging ports and repositions the lids after charging; seals ports with coal or sealing compound; and is responsible for general maintenance of the top of the battery. His major exposure is related to the charging operation. Tar chaser (spray tender): Loosens tar accumulations in the collecting main by means of a rod with a spoon-type end; while doing this, may be exposed to hgh concentrations of polynuclear aromatic hydrocarbons. Pusher machine operator: Directs the leveling bar into the oven to level the deposited coal; removes the oven doors and activates the pushing ram through the oven to push out the coke. At some facilities there may be a separate pusher side door machine. These two jobs (where separate operators were involved) have been combined for the purposes of this report. Coke side machine operator (doorman): Removes the coke side oven door and positions the coke guide so that hot coke is pushed through the guides into the quench car. Benchman: Cleans the oven door and jambs and inspects for damage; douses and removes fallen hot coke and, at some facilities, patches cracks in the door seal. Quench car operator:' Drives the quench car (hot car, locomotive) with its load of hot coke to the quenching tower and deposits the quenched coke onto a wharf. Luterman: Applies luting compound (a sealant) to the doors. Seven of the ten coking facilities have "self-sealing" doors, and this job 1972 is found only at those plants that have Oven doors designed to be luted. Heater: Checks the temperature of each oven with a pyrometer, regulates gas reveras, and maintains records. This job involves vavbg periods of exposure at different locations with a significant amount of time in the control area. Miscellaneous category: Includes wharfmen. who control the gates which direct the quenched coke onto a conveyor; spellmen, who substitute for regular operators during breaks; patchers; and repairmen. Among these work positions, the larv car operator, lidman, and tar chaser work on top of the battery; the luterman, benchman, and door machine operator work on the sides of the bat. tery. The pusher machine and quench car mn on tracks parallel to and a few yards from the battery. Sampling Procedure Breathing-zone samples were collected by means of battery-operated personal-type port. able air pumps. Preweighed silver membrane filters having an 0.8-micron pore size were mounted with cellulose backup pads in plastic holders and attached to the shirt collars of the workers. Only the small plastic plug was removed during sampling because of the possibility of the filters' being burned by hot cinders and to minimize tampering and accidental damage. The workers were fitted with the sampling apparatus at the start of the work shift. Samples were collected on a continuous basis so that integrated samples, reflecting periods of peak expcsxe as we!! 3s rest breaks, were obtained. Each sample was collected for as long a period as possible-that is, until the pump's battery became exhausted or until the filter became so clogged that the resistance was too great for the pump to overcome. Each sampling apparatus was checked penodically and the flowmeter reading recorded. Airflow calibrations were maintained for each sampling apparatus. Average sampling rates varied from 2.0 to 2.8 liters/min. Total airvolumes ranged from 103 to 1220 liters. SktY lob Title Samples Averagea Mediana Qke side benchman &or machine operator Hrter Larry car operator Lidman laterman Yallaneous Mer machine operator rPlher side benchman OpMch car operator hchaser 18 1.08 0.77 25 2.1 1 1.70 39 1.07 0.82 39 3.05 .2.73 61 3.22 2.30 18 2.57 2.30 18 0.93 0.95 23 0.39 0.33 - -28 2.03 1.17 LJ U.Y4 0.43 27 3.14 2.37 Total 319 2.08 1.42 `Milligrams per cubic meter of air. %v = 0.2 mg/m3 of air, based on exposure for an 8-hour work day. N.D.-none detected, Rangea 0.09- 2.14 0.04- 6.51 N.D.- 2.98 0.28- 8.78 0.42 - 17.89 0.25- 4.82 0.18- 2.16 N.D.- 0.93 N.D.-14.59 N.D.- 7.20 0 . 0 4-14.10 N.D.-17.89 <TLV~ 5.6 4.0 10.3 0.0 0.0 0.0 5.6 30.4 10.7 26.1 7.4 7.8 W n t of the samples had air volumes greater lhtnSO0 liters. We were concerned that an internal bias w t have developed from clogged samples- h t is, that samples with a low total volume .enC those that had been subjected to short paiods of extremely high concentrations, and h t these samples made our results an amalgam "ria@of normal and abnormal exposures. lbtirtical evaluation indicated that samples of b* total air volume had concentrations of par- *&and coal tar pitch volatiles as randomly h n h t t e d as those with greater air volumes. we interpret this to signify that our concern unjustified. We infer, from our survey ex- bee, that the moisture content of the air a*448 great effect on the clogging of the filters; b,we experienced a high incidence of clog- in samples collected on the coke wharf. at this location is not particularly dusty, b b very moist. b-ribedh e r a l air samples were taken to determine a t i v e conceitrations at various locations a &e coking facilities. These samples were col- bd Using the filter-backup pad arrangement previously. Electrically powered kphaving flow rates of 15 to 30 liters/min i used to collect samples where electric i Was available. The mean total air volume liters. The samples were analyzed by a standardized benzene extraction m e t h ~ d . ~Ea`c~h sample required eighteen gravimetric determinations (made with an analytical balance accurate to 0.01 mg) and 3 hours of refluxing in a Soxhlet extractor.' Total particulate concentrations were also calculated, Results Three hundred and nineteen samples were collected in the workers' breathing zones. The results of analysis are indicated in Table I. Ex- posures at all job classifications were greater than the threshold limit value. It should be stated that our laboratory personnel noticed staining on many of the backup pads in the later surveys. We theorize that improper seating caused leakage around the edges. A lack of history about this staining makes it impossible to determine if (as we believe) this was the case in the earlier surveys, and no attempt was made to adjust our results. Figure 1 depicts the relative magnitude of exposures for those job classifications which are located in specific areas. The figure indicates that the magnitude of exposure is inversely proportional to the distance from the ovens. For example, the larry car operator, the lidman, and the tar chaser work directly on the ovens and have much greater exposure levels than the r I u 3 MILLIGRAMS PER CUBlC METER O f AIR Figure 1 . Comparison of exposure versus job title. quench car operator and the pusher machine operator, who are several yards from the oven doors. Table I1 lists exposure levels according to company. The average of exposures at all companies is greater than the threshold limit value. The differences among companies are influenced by the number of samples collected at each job classification, and interpretation of the results is also complicated by the fact that some jobs do not exist at some 'companies. Because of these factors. comparison of average exposures between companies is difficult. Table 111 lists the variation in the average (mean) o i exposures among job classifications and among companies. We realize that some of the averages are based on a small number of samples, but the trends are clear. The pusher machine operator and the quench- car operator have relatively low exposure (except in one instance), which is to be expected because of their relative distance from the coke ovens. The coke side benchman and the pusher side benchman have roughly the same duties and their exposures per company are comparable, except in one instance. This table also indicates that some of the differences among companies may be more apparent than real. For example, the high overall mean for company E is explained by the unusually high exposure rates found for the tar chaser. Company A, with the small~t overall mean, has uniformly low exposure rate, and company H, with the greatest overall mean. has uniformly high exposure rates. However, if the tar chaser's exposure at company E is ex. cluded, the x2 test indicates no significant dif- ferences in exposures among companies at 3 95% confidence level. Table IV lists the results of sampling in loca- tions where workers are apt to congregate and indica:::, :hat exposures may be found in any location on or near a coke oven. Because of the interest in respirable sampling, an attempt was made to correlate the amounts of coke oven particulates in samples collected as described with those collected using a lo-mm nylon cyclone elutriator.' The results of the twenty-four oaired samples uc listed in Table V. The correlation coefficient is 0.30, indicating, in these samples, a very degree of correlation. The presence of BaP (3,4-benzpyrene) W@ I AmcrioPn Indusrrinl Hygiene Association Journal TABLE I1 Exposure to Benzene-Soluble Fraction of \ Coke Oven Particulates According t o Company Number of Average Plant Samples CTPVa Rangea A B C D E F G H I J Total 22 24 24 28 17 40 40 34 44 -4 6 319 1.02 1.68 2.16 1.55 3.30 1.98 1.95 3.24 1.94 2.02 2.08 0.09- 3.45 0.03- 9.04 N.D.- 8.78 N.D.- 6.21 0.24- 14.70 N.D.- 6.89 0.06- 9.24 0.08-1 7.89 N.D.-14.59 0 !7- 7.20 N.D.-17.89 aMilligrarns per cubic meter of air. b.TLV = 0.2 rng/m3 of air, based on exposure for an 8-hour work day. N.D.-none detected. 465 <TLV~ 2 2 4 2 0 4 2 3 5 -1 -2 5 319 = 7.8% investigated by fluorescence spectroscopy. Seventy-five percent of 2 12 samples fluoresced at 403 mp upon activation at 373 mp. This Concurs with the activation-fluorescencecharac- teristics of BaP. An attempt was made to investigate the relationship between CTPV and total particulate. This was done with the hope of establishing m e estimate of the CTPV concentration in a sample. A fairly strong linear relationship was found to exist between CTPV and total particu- late, with a correlation coefficient of +0.72. It was observed that several workers were Wearing respirators while standing in dust clouds. The Pennsylvania Division of Occupational. Health has recommended the use of retpirators during intermittent periods of high q o s u r e , as an interim measure. Obviously, engineering and operational changes will be Wssary t o control the exposure of workers, PMiCularly topside. The industry is engaged in extensive program directed to these objeck S . Ultimately the answer may lie in automation of these jobs, in operational or process changes such as a continuous coking process, or elimination, through some process of making *l without coke. These alternatives are also under study by the industry. The lack of adequate maintenance is apparent in many plants. Leakage at the oven doors is widespread and difficult to control in the older ovens. Strict attention to maintenance and repair of oven doors and jambs can minimize this source of exposure. The nation's steel manufacturers and the American Iron and Steel Institute (AISI) are working together to develop measures to control exposures to polynuclear aromatic hydro- carbon. One interim approach is directed to the design of a new respirator with a batterydriven pump to pull air through an English-wool filter into a facepiece. To control emissions during charging, dust collection equipment on the larry car has been used in Europe and has gained some popularity in this country. This equipment presents some safety hazards (explosions), and stack tests on the earlier installations have not been too encouraging. The AISI proposes to control emissions during the charging operation by using the ovens themselves as exhaust ventilators. By redesigning the standpipes, adjusting the steam aspiration, and controlling the sequence of charging into the oven (only one lid removed at a time), it is believed possible to increase the *j : .f ' ~9 466 suction enough to significantly reduce emissions. Redesign of the larry car's hoppers and sequential charging will eliminate emission through the hoppers and blockage of the draft through the oven due to uneven filling. Also, the larry car cab will be enclosed and the opera- tor will be supplied with filtered air. Magnetic lid lifters will reduce the lidman's exposure. If these proposals prove to be workable, a significant step toward controlling exposures and air pollution will be accomplished. It must be emphasized that these suggested changes are expensive and complicated; they would require constant maintenance and are several years in the future. Until they prove to be effective, reasonable supervision and 'enforcement of operating practices, maintenance, and personal protective programs must be maintained. Summary Evaluation of 319 breathing zone and 31 general air samples indicates that exposure to CTPV for all job classifications in all coking facilities is greater than the threshold limit value of 0.2 mg/m3 of air, based on an 8-hour daily exposure. Exposure tends to be proportional to proximity to the coke ovens-the nearer the worker to the oven, the greater his exposure. Simultaneous samples were taken by means of a cyclone elutriator in 24 cases, and these samples were compared to regular samples. Very slight correlation was found. The presence of BaP was tentatively identified in 75% of 2 12 samples. The relationship between volatiles and total particulate was analyzed statistically. Correlation coefficients of 0.7 to 0.9+ (depending on job and/or site) were determined. More work is necessary on this aspect. Industry's proposals for the reduction of exposures were reviewed. It is technically feasible and hygienically desirable to eliminate the job of luting coke oven doors. Conclusion At the time the study was initiated, a litera- July, 1972 TABLE IV Concentrations of Coke Oven Particulates (Beqzene-Soluble Fraction) in Selected Locations ~~ Location Number of Samples Averagea Mediana Rangea %<TLVb Reversing room Foreman's office Wash room/line-up room Vending machine area Total 15 5 1 -3 30 0.30 0.10 0.56 0.20 0.2 1 0.30 0.09 0.54 0.04 0.16 N.D.-0.80 0.04-0.16 N.D.-1.66 N.D.-0.56 N.D.--1.66 46.1 100.0 28.6 66.1 53.3 aMilligrams per cubic meter of air. bTLV = 0.2 mg/m3 of air, based on exposure for an 8-hour work day ?!.I".n ~ ndei tected. TABLE V Comparison of Coke Oven Particulates (Benzene-Soluble Fraction) Collected Using a Cyclone Prefilter versus Samples without Prefilter Job Title With Prefilter Without Prefilter Larry car operator Lidman Coke side benchman Pusher side benchman Heaters Tar chaser Pusher side machine operator Door machine operator Ouench car ooerator 2.13 1.66 0.42 0.17 1.32 0.31 1.13 1.10 1.30 1.59 2.46 0.77 0.13 1.66 0.48 0.1 5 1.52 0.92 1.29 N.D. 1.06 0.54 0.98 0.22 2.98 5.66 3.33 2.20 1.oo 1.67 0.35 3.75 1.66 2.79 1.44 1.52 0.52 1.35 0.62 1.98 2.17 1.36 1.05 0.71 1.18 0.30 0.84 N.D. 467 &e search revealed a dearth of information m b l e about CTPV and coke ovens. It was learned that several steel companies had conducted surveys and that the AIS1 had begun to fmulate proposals with regard to evaluation control of coke oven emissions. It is %IPsted that, in view of the time, money, and effort that will have to be spent to combat this problem, a group should be formed to coordi- efforts. We believe that the combined interest of industry, labor, and government is needed to improve the conditions for the coke oven worker. References l.Reed, D.D., and C. Buck: Cancer in Coking Rant Workers. Brit. J. Ind. Med. 13:265 (1956). 2.Dol1, R. ef al.: Mortality of Gasworkers with Special Reference t o Cancers of the Lung and Bladder, Chronic Bronchitis and Pneumoconiosis. Bn`r. J. Ind. Med. 22: 1 (1 965). 468 3. Hucper, W.C.: Environmental and Occupational Cancer. Public Health R e p t . Supplement 209. 4. Lloyd, J.W.: Long-Term Mortality Study of Steelworkers. V. Respiratory Cancer in Coke Plant Workers. J. Occup.Med. 13:53 (Feb. 1971). 5. Documentation of Threshold Limit Values, revised ed. p. 44, American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio (1966). 6.Coke: Steel's Slow-Burning Dilemma. 33/The Magazine of Metals Producing 5:53 (April 1967). 7.Richards, R.T., D.T. Donovan, and J.R. Hall: A Preliminary Report on the Use of Silver Metal 2 Membrane Filters in Sampling for Coal Tar R ~ , , i ,,,Volatiles. Amer. Ind. HYg. ASS.J. 28:590 ber 1967). , &Standard Procedure for collection and ~ m l ~ b Coal Tar Pitch Volatiles (Benzene-Soluble h. tion). Pennsylvania Department of Health, Divirb, of Occupational Health (January 1970). 9.Tomb, Thomas F.: E v a l w i o n of the pmC- Characteristics of a Horizontal Plate EIutrhtop orrd of a 10-Mm Nylon Cyclone Elutriator. U.S. D~~~ ment of the Interior, Bureau of Mines, Wathln~o,,. D.C. (1970). Received May 14, 1971 I , . ,- ... .- `. , :* Q Approved Respirators Listed Respiratory protective devices currently approved for use in hazardous mine atmospheres are listed in a report by the Bureau of Mines, U. S. Department of the Interior. The devices are approved jointly by the Secretaries of the Interior and of Health, Education, and Welfare. The list covers devices approved for use in oxygen-deficient atmospheres, and in the presence of specific gases, vapors, dusts, mists, and fumes. An appendix to the report provides names and addresses for the manufacturers of the listed devices. Tables in the publication list devices jointly approved for use in mines, without further testing, until March 30, 1974. Each table gives pertinent data on one type of respirator, including the Bureau "Schedule" or requirements under which it was tested and approved. Tables for respirator types are: Self-contained breathing apparatus; gas masks; supplied-air respirators; dust, fume and mist respirators; and chemical cartridge respirators. Under newly established rules the Bureau of Mines will continue to pioiixilgate reyirernents for mine respirators; the National Institute for Occupational Safety and Health will test them; and those that pass will be approved jointly by the Secretaries of Interior and of HEW. Also, the Bureau will publish lists of devices approved for use in mines, while NIOSH will list those approved for use in other hazardous industrial atmospheres. The testing of respirators, according to schedule requirements, has been a function of the Bureau of Mines for many years and is now in the process of being transferred to NIOSH. Respirators Approved by the Bureau of Mines as of May 24, 1972, Information Circular 8559, by E. J. Kloos and R. H. Schutz, is a revision of a previous list. A free copy of the new list can be obtained from the Publications Distribution Section, Bureau of Mines, 4800 Forbes Avenue, Pittsburgh, Pennsylvania 15213. Requests should note both the title and number of the report. I i