Document VjoOOE38qme44zXargjz4Gn98

R&S 142764 How to control carcinogens in chemical production Copyrighted Material Do Not Reproduce Without Publisher's Permission Which makes more sense, zero exposure to a few known toxic chemicals or minimizing exposure to all ch micals? The evidence points to the latter. The symposium title, "Workplace Control of Carcinogens," is enlighten ing. It indicates that the membership of the ACGIH agrees that carcinogens can be used by industry and that it is possible to control exposures to acceptable levels. by Ralph R. Langner. Director. Industrial Hygiene Laboratory. Health and Environmental Research, Dow Chemical USA. Midland. Mich. This acceptance by ACGIH of carci nogens in industrial operations may be ahead of many academic and indus trial leaders. There are several re search and development directors who have banned the use of the 14 carci nogens, even in research. Of course, these same directors would not ban asbestos, and vinyl chloride wasn't supposed to appear as a carcinogen. This type of reasoning is also prac ticed by many industrialists. They ask, "Is the proposed material on the NIOSH list of 1500 suspected carci nogens?" If it is, they search for and are willing to use a substitute product for which little or no toxicological information is available. PROVEN WAYS Carcinogens can be controlled in chemical operations using the same proven techniques used with other toxic materials. The emphasis on eliminating exposures to carcinogens may result in empkryee overexposure to other toxic chemicals, some of which may prove to be carci nogens in the future. Few, if any, processes use only one chemical. As professional industrial hygienists, we should be looking at the "total MARCH/APRIL, 1977 n system." It is unrealistic to discuss zero exposure to a select few chemi cals. Rather, we should be working toward minimizing exposures to all materials. What are the proven techniques? Substitution, containment, local ex haust ventilation and continuous area monitors equipped with alarms--have all been used successfully by industry to control overexposures to toxic chemicals, including carcinogens. Experienced industrial hygienists know that substituting a material of unknown toxicity for a known toxic material is a misuse of the substitu tion concept for controlling industrial hazards. This practice is foolish and fails to recognize our modem techno logical ability to control releases and to minimize employee exposures. SUBSTITUTIONS What are some re alistic substitutions? Some of those that come to mind are toluene for ben zene as a hydrocarbon solvent; 1,1,1trichloroethane for 1,1,2-trichloro ethylene in vapor degreasing; a select organophosphate insecticide for ethy lene dibromide in grain fumigation. REACTOR STUFFING BOX COVER i| gearbox air inlet i S. Carcinogens can be controlled just like other toxic chemicals. Likewise, the substitution of flam mable hydrocarbons or the use of highly corrosive caustic solutions rath er than trichloroethylene for metal degreasing should be thoroughly stud ied. Technically, both have been used successfully, but the risk of human injury, under field conditions, and the lack of data demonstrating that tri chloroethylene has caused health prob lems, when used properly as a de greasing solvent, poses a benefit/risk question. It is impossible for any of us to determine if it is worse to die from bums than from cancer. Is blindness from caustic at age 30 worse than a remote possibility of cancer at age 65? Overreaction to carcinogens can lead to unwise decisions. OPEN WINDOWS? Ventilation is another technique used to control employee exposures. Historically, gen eral ventilation--a concept burrowed from the sanitary engineer--has been used widely. Open the windows and dilute the contaminant to an accept able level! Today the industrial hygienist must work side-by-side with the waste control engineer and, in many small plants, they are one in the same. It is no longer acceptable to exhaust toxic vapors into the ambient air. Although general ventilation is still used, tide high. energy cost of moving and heating luge volumes of air has caused industrial hygienists and ven tilation engineers to look for better solutions. Localized ventilation is too seldom used and, when used, too frequently abused for controlling exposures to chemicals. When properly designed and operated, local ventilation offers one of the lowest cost control methods available. Not only is the volume of air reduced, but it allows the point of capture jto be strategically placed to minimize employee exposures. Be cause the volume of air is small, filters and scrubbers can be used efficiently to remove the contaminant and, in some cases, to recover and recycle enough material to pay for the operat ing costs. PRECAUTIONS With toxic materials such as carcinogens, local ventilation can be installed as a precautionary measure, i.e., it is operating if a leak develops in a pump, valve, or seal. If the exhaust air is monitored, minor leaks can be detected and the neces sary repairs made before employee exposure/overexposure is imminent Another technique used to prevent employee overexposure is area moni toring. Continuous, sequential area monitoring has been used in our plants for many years. In recent years, area monitoring has been ques tioned and the use of personal moni toring has gained in popularity. Emphasis on documenting em ployee exposures, proving noncom pliance, and'forgetting the ultimate goal of all industrial health practi tioners i.e., the prevention of em ployee oyerexposure, have caused many industrialists to shy away from this valuable tool Continuous, sequen tial area air analysis is the most effec tive method of controlling employee overexposure to all chemicals. ALERT These instruments, when equipped with alarms and readout devices, allow the employee to know the airborne level in an area before entry. Appropriate respiratory protec tion can be worn to prevent exposure while completing a work assignment i I OCCUPATIONAL HEALTH AND SAFETY R&S 142766 :r : &at' 1 i f: SAMPLING BOX, SIDE VIEW R\ , I PROCESS LINE OR VESSEL RAM-TYPE p-v SAMPLING i M \VALVE 3i\\ l oinor ecesloyee ent. went nonimrea our cent quesuoni- emwommate racti- eminsed from |ueneffecloyee when idou|^ efore otecosure ment =ETY MARCH/APRIL, 1977 or while making necessary adjust ments or repairs. Certainly, this approach is far better than placing an adsorption tube in the breathing none of the employee, using a carefully calibrated air sam pling pump and a validated analytical procedure to document what the expo sure was. When these area analyzers are equipped with a computer to handle vast amounts of data, daily printed exposure records are possible. If posted in the work area, the calcu lated exposure record can be a valu able training tool for operating per- Substituting an unknown chemical for a known carcinogen is dang rous. sonnel. Gas chromatographs, infrared units, ultraviolet and nonspecific com bustion analyzers have all been adapted to this use. MONITORING The OSHA vinyl chlo ride standard accepts continuous area monitoring as a method of deter mining employee exposure, NIOSH could make a valuable contribution by collecting and analyzing the data from the many vinyl chloride plants using the various monitoring techniques and reporting to industry those sys tems that are acceptable as well as those that have been shown to be inadequate. -`V R&S 142767 Containment, or the use of closed systems, is another method to control exposure to toxic chemicals. The BCME (bis-chloromethyl ether) prob lem was associated with exposures that occurred during "open kettle" operations in the 1950's and 1960's. Employees working in the closed system plants did not develop the characteristic oat-cell carcinoma nor have new cases of cancer been reported in employees working only with closed systems in older plants. New plants have closed systems equipped with vent scrubbers that minimize both employee and public exposures. SAMPLING Changes in process sam pling have reduced potential employee exposure. Opening of process lines for sampling has been eliminated in many cases and reduced in others^ In-line analyzers are being used in most new Local ventilation is an effective way of ridding an area of fumes. plants and they have been added to many of the older processes. Gas chro Fig. s matographs are used in most plants for quality control. They require microliter quantities. The past prac tice of draining quantities of material plants. (Fig. 1) This is a drawing of a thyl ether). The exhaust system uses a into an open container to obtain a shroud that can be placed around a low flowrate. Yet, there is a high representative sample has been elimi reactor agitator shaft or other moving capture velocity at the point of poten nated. part that is subject to leaking. Fig. 2 tial leak. New plants would use Let's look at some of these shows a shroud on a old-style reactor mechanical seals rather than packing techniques, as installed in operating handling CMME (chloromethyl me glands. PUMPS LEAK. A similar shroud can be used on pumps. Pumps leak. The it*-^COMPARISofeo^XPOSURE i-EVELS TO ETHYLENIM question is, when? Continuous area samplers can be used to detect early ^ ^t^^^#ipLANT'PERSONNEL?1966-1974^ -p &&& leaks. After spending thousands of dollars on research, we have developed -" . - - 'V 35V. 8-HOUR TWA EXPOSURE > ~ an air monitoring technique that LEVELS (PPM, V/V) V-.j. measures (sequentially) both CMME C :%ioB CLASSIFICATION ' - ' -. V ETHYLENE : ETHYLENIMINE DICHLORIDE and its carcinogenic impurity, BCME, at the 1 ppb level. At the same time, process research ASSISTANT SUPERINTENDENT (1966) SUPERINTENDENT (1974) % . V * 0.06 <0.1 4.9 ; V 1.4 - has continued to reduce the formation SENIOR PRODUCTION ENGINEER (1966) 0.04 2.8 PRODUCTION ENGINEER (1966) .V 0.06 4.9 , R&D ENGINEER (1966) . 0.08 8.8 ; PRODUCTION ENGINEERS (1974) PRODUCTION CHEMIST (1966) TECHNICIAN (1966) ........ . ' FOREMAN (1966) FOREMAN (1974) - . - ------- <0.02 0.04 0.08 0.08 <0.02 5.9 2.8 'V 7.9 8.8 6.6 1 -SsJr- - ' V X AREA SAMPLES TOTAL CHLORIOE CALCULATED ...AS CMME CONTROL "A'' OPERATOR (1966) CONTROL "A" OPERATOR (1974) CONTROL "C" OPERATOR (1966) CONTROL "C" OPERATOR (1974) CONTROL "C" (SRO) OPERATOR (1966) CLERK (1966) JANITOR (1966) 0.04 <0.01 0.17 <0.04 0.04 0.02 0.02 2.8. 1.0 13.5 10.2 8.4 1.5 1.5 ." NO. OF AVG. ,range DATE : SAMPLES (PPM) ' (PPM) 1949 1952 1957 1961 .7 5.2 2.Z-8.7 3 1.1 0.15-2.65 230 - 0.7 -- - 0-12 . 8 ' 2.5 1-8 Fig. 6 Fig. 7 ^rriiDATinrOAl HFA| TH AND SAFETY R&S 142768 of by-product BCME. This research was done even though the existing OSHA standards for CMME and BCME neither require measurements nor offer an incentive for industry to do this type of work. A vinyl chloride pump shroud is shown in Fig. 3. Seal less pumps are available for some materials, but they do not perform in all operations. The use of remotely operating valves also reduces employee overex posure. Even though the valve is oper ating remotely, the area monitor will detect leakage and the operator will be able to put on proper respiratory protection before he leaves the pres surized control room. Monitors can be set up to alert workers to a rise in contaminant level. Let's move on to sampling devices. The use of an enclosed sampling box' with cross ventilation will minimize exposure. (Fig. 4) The sample valve also minimizes the quantity needed to obtain a representative sample. By pass sampling prevents the need for open systems. (Fig. 5) A "double ended cylinder" can be used to collect gas samples with little or no release. These sampling techniques can be used effectively in noncarcinogen plants also. THE RECORD Now, let's turn our attention to employee exposure rec ords from plants using this technol ogy. (Fig. 6) Measured employee expo sures in our ethylenimine plant in 1966 and 1974 demonstrate good control. This plant, put in operation in 1963, uses a gas chromatograph for sequential area air monitoring. There has been little change in the airborne levels. Has the posting of "CANCER SUSPECT AGENT" signs in 1973 and the resulting mental anguish bene fited these employees? The measured airborne levels of contaminant in the CMME plant provide an interesting study in the evolution of the chemicals industry and in the technology used by indus trial hygienists, (Fig. 7) The early samples taken in the 1950's were collected using a hand-operated sam pling pump and silica gel as the adsor bent. The silica gel was burned and the resulting chloride was scrubbed and measured using the Volhard colori metric method. The presence of BCME was unknown and it and all other airborne chlorides were calcu lated as CMME. Repeat samples in 1952 demonstrated continued good control. In 1957, a new technique, infrared, became available. This in strument allowed us to be more specific and measured primarily CMME. By attaching a multipoint sequential sampler, many analyses were possible. Again, good control was demonstrated. Repeat sampling in 1961, 1966 and 1970 showed little change. (Fig. 8) OVERREACTION In 1969, the report on the carcinogenetic effect of BCME was published. Results of analyses from the various producers indicated that CMME contained 7-10% BCME. Industry responded by developing analytical techniques for monitoring BCME and these methods have been published. We were now able to measure both CMME and BCME and. in general, everyone overreacted to measuring the known carcinogen, BCME. In reality, if the CMME was controlled, the BCME (less than 10% of the CMME) would be controlled also. Data from our plants demon strated that both were being con trolled. After 27 years of controlled TIME-WEIGHTED AVERAGE ,, EXPOSURE TO CMME (PPM) JOB $ 1966 1970 1971 1972 OPERATOR #1, 0.5. OPERATOR #2V*,7.- . .. > 2.4 OPERATOR , . : 1.8 OPERATOR #4 OPERATOR #5 ' T- ' 0.6 OPERATOR # 6 * 024^ 0.08 OPERATOR #7?%: - 7- r^o.04 OPERATOR-#8" pg ' -0.04 - > Ffe. 8 0.29 0.3 0.1 0.43 0.24 0.10 0.24 8-HOUR TWA EXPOSURE TO BIS-CHLOROMETHYL ETHER (PPB, V/V) BY QUARTER, 1972-1975 : ,V)v .. FIRST .yS~YEAR QUARTER SECOND?, THIRD, ^.FOURTH '.' QUARTER QUART HARTER ~Ma VERAGE OPERATOR -# 1 ; i.: .. - it.1972l- , 2.7 :vo:t973^'"v . 1.2 1974 ty 0.99 1975 ' ,0,60 OPERATOR 3*2^ , "4. 3,1 ,0.36 0.40 1975:.v.` - : : 0.15 OPERATOR #3 . 0A1 1973 ' 0.40 1974 ;r>; - ; 0.42 1975 0.37 ^0.15V:-; 0.65 '- -,033Vi M1 *8 .'V.WS& 10.07, 0^3?** ^ mie ;# 0.91 0.08 0.34 . 0.74 V - 0.87 oj2.i .023v:| ?||SS'v0 W11^1P^#0.21 7r 0.18. vtVvV: -0.22 0,16 7- 0.41 ' 0.09 V.- 0.14 Fig. 9 8-HOUR TWA EXPOSURE TO BIS-CHLOROMETHYL ETHER (PPB, V/V) BY QUARTER, 1972-1975 ' YEAR FIRST QUARTER OPERATOR #4 1972 1973 1974 1975 OPERATOR #5 1972 1973 1974 1975. OPERATOR #6 1972 1973 1974 1975 HEAD OPERATOR 1972 1973 1974 1975 3.0 023 0.08 0.06 2.2 0.31 0.14 0.09 0.64 0.10 0.03 0.02 3.0 0.26 0.11 0.07 SECOND QUARTER 0.23 0.15 0.05 0.04 0.25 024 0.07 0.06 0.08 0.06 0.02 0.02 0.30 0.17 0.06 0.04 THIRD FOURTH QUARTER . QUARTER AVERAGE "0.17^ 0.15 *" 0.32 ' - ''-''; ?." 0.11 0,05 " 0.06 0.05 ^ 0.03 V 0.64 020 0.06 0.04 0.17%& a.0.18-- ' 0.50 ' 0.17 0.07' 0.10 0.07- ` 0.04' - . 0.71 0.31 0.10 0.06 0.08 . 0.14 0.02 0.02 0.06 0.04 0.02 0.01 0.19 0.08 0.02 0.02 0.29 0.18 0.92 0.37 0.13 0.23 0.06 0.07 0.07 0.06 0.03 0.05 F`g- JO MARCH/APRIL, 1977 TIME LOG 1 > . LOC 2 LOC 3 w LOC 4 LOC 5 8:06 AM 8:25 AM 10:24 AM 1:00 PM 3:19 PM 5:37 PM 7:55 PM ,10:14 PM 3.3 6.0 5.8 4.6 12.3 3.6 4.5 6.2 5.3 5.0 10.7 5.6 4.2 ,3.1 3.2 V- 2:50'AM^ ':%i>3.1 2.9 3.4 5:09 AM1^5-# 3j . 3.0 3.0 ' '7;2TAMS^?r3:0 AVERAGES-^^fel^ Sffi SHIR- *JSgKpSsb; Q':-SHIFT23|j|i\6. p f}.4G'ii%i 5.1 5.8 T0.63pfts?6.3 `_6.4 %. ~VSH1RJ#^^3:3,W!B SZM.& 5*3.0 A ;3.2 f 6.7 ' " 4.9 ' c5."2 TIME-WEIGKTEO'AVERAGE EXPOSURE'iTO CMME JOB'CLASSr^SHIf^H, "J'- SHIFTS^,,;;.. ^FiNeop::^ 5.33 2.75' Fi.5tW^: ^:- ' Vi.U)RiPKGI^-,;jtl 35 1.02&:;v- LOC 6 2.8 7.3 6.3 6.6 7.9 4.9 2.4 3.2 3.2 3.1 5.5 5.5 3.2 4.8 BLANK 3.3 3.1 4.8 6.9 6.8 4.1 3.9 3.3 3.1 3.0 2.9 4,5 5.0 3.1 4.1 ND: 1 ND I|nd- . ND 0.8 0.5 ND ND ND ND ND ND ;ND-rf ND ,.ND'.:J Pnd ' ND- ' `-'ND#] KrNO;... NO ND; iNDA" ND f ^ v- SfNO&^rND ^ND^ND ^ND4 ND pNDV:-S-ND 'V-ND^; 4NDY1 ' iV`Ni Of* 1 _ ' ' >r,;v ,, NDv*SiNOT DETECTEDY0.5:PPB MINIMUM DETECTABLE) v.: _ , M7fc%^MAINT^?DR^`--------- --------- Fig. 12 OPERATOR JOB TfTt^^ff ^OAT^tJ VINYL CHLORIDE VINYUDENE CHLORIDE POLYMER OPERATORS#**;, 1-08-75^>^42.4 -yvk ' rasv- 5-12^5^^&0.2;^-- 6-13^5^#t4.5^Y POLYMER OPERAT 3-12-75^'.':'^-1.7.yv '*i r, :- v;^ . - ..4-- - ' 3-27-75^ r . : 0.6 4-10-75^, 10.5V 5-21-75 ?* - 6-16-75 .^ ;,n 1 -1 POLYMER OPERATpR#^ :^1-06-75;W7:4*17.4 2-13-75W' 4 .2.3 3-12-75 \ 0.9 4-02-75 .0.4 5-12-75 0.3 6-17-75 0.5 POLYMER OPERATOR *#4 2-27-75 0.3 3-12-75 : 4.7 4-10-75 2.9 5-21-75 3.6 6-16-75 1.3 POLYMER OPERATOR # 5 3-13-75 2.9 4-24-75 0.8 5-19-75 0.2 POLYMER OPERATOR #6 3-13-75 0.7 4-24-75 5.9 6-03-75 0.3 1.5 10.1 0.2 1.0 4.5 1.0 1.1 5.9 0.4 5.0 0.7 2.0 0.7 0.4 0.2 0.8 1.3 0.3 0.7 0.3 1.1 0.8 0.1 2.7 1.5 0.1 operation, using closed systems, no cases of oat-cell carcinoma have been observed in these employees. We recently built a new CMME plant and, as the exposure data show, the process research which lowered the BCME formation has also lowered the BCME level in the environment. (Figs. 9-13) Has the cost of this research benefited these employees or society? Since plants using closed systems were already safe, it is diffi cult to demonstrate a health benefit from this costly research. VINYL The last carcinogen plant to be discussed is vinyl chloride. I know of no vinyl chloride plant, either producer or user, that doesn't use respirators. The emphasis on docu menting employee exposure rather than controlling exposure has been very costly. Certainly, OSHA and/or NIOSH owe both the employees and employers a report on the results of the present standard. (Figs. 14-15) What are the benefits of a 1 ppm standard versus a 10 ppm standard? Both employees and employers are very much aware of the cost to them in comfort and dollars, respectively. Technology is available to control toxic chemicals, including carci nogens. Industry is being forced to use this technology to remain com petitive. The bottom of the industrial cancer iceberg has failed to appear and the rate of lung cancer due to smoking tobacco is rapidly increasing. (Fig. 16) Dermatitis continues to be ' '. COPOLYMER PLANT^"-' OPERATORS' 8-HOUR TWA : \ : EXPOSURE IN PPM (V/V). , -.. , ' s,, X-k- , OPERATOR JOB TITLE Q ^UJ E; 9ir ^34;L4-C0-1 , >o OPER #1 OPER #2 OPER #3 OPER #4 OPER ^5 1-07-75 1-20-75 4-02-75 6-16-75 1-13-75 3-10-75 4-10-75 5-08-75 6-06-75 2-27-75 3-10-75 4-29-75 3-10-75 4-29-75 5-20-75 6-18-75 Fig. 15 3.8 1.7 0.3 0.3 0.2 0.2 0.9 0.1 0.9 0.6 0.4 0.3 0.1 0.2 0.3 0.1 0.4 0.1 10.2 15.4 0.6 3.0 0.6 0.8 0.6 3.0 0.6 0.8 0.2 0.3 0.3 0.1 OCCUPATIONAL HEALTH AND SAFET i, no ;how, ered -red nent this tyecs losed diffi- the leading industrial disease. Are we using our limited industrial hygiene resources effectively? No. As stated previously, employee exposures to carcinogens can be controlled using the proven industrial hygiene methods. Our efforts should lie expended on the total work envi ronment rather than overemphasizing those few compounds that may cause latent disease. oh&s :nefit nt to mow ither RESULTS OF ANION EXCHANGE PLANT PERSONAL MONITORING CONCENTRATION >'7 (PPB. V/V) use locuither been d/or and a of 4-15) ppm ard? are hem ily. itrol arci- OPERATOR NUMBER SHIFT DATE CMME BCME 61610 27635 67145 60450 53841 66359 61920 67244 67145 .AFTER- 3/15 NOON MIDNIGHT -3/15 DAY .3/16, AFTER- 3/16 NOON , MIDNIGHT . 3/16 .DAY ,3/17 / -AFTER- 7.3/17 - NOON - MIDNIGHT i 3/17 DAY 3/18 6.50 < 0.01 15.1 .0.07 1.42 < 0.01 0.21 < 0.01 0.21 .< 0.01 0.34 <0.01 0,471 '< 0.01 1.1- <0.01 0.52 <0.01 Fig. 13 tm trial pear e to dug. } be Health protection must be part of plan ning, continued from p. 31. Results of the air sampling program are summarized in Table 1. From these data it was concluded that respiratory protection was neces sary during cleanup and maintenance The industrial hygiene program is a simplistic approach to a very complex problem. Certainly, adequate control measures can be developed to mini mize the exposure potential. Data interpretation is confounded because of lack of adequate techniques to eval uate the impact of complex mixtures 3. Reid. O.D., Buck, C.: Cancer jn Coking Plant Workers. Br. J. Irib. Med. 13:265-69. 1956. 4. Redmond, C.K., Ciocco, A.. Lloyd, J.W., Rush. H.W.: Long-term Mortality Study of Steelworkers--VI. Mortality from Malignant Neoplasms Among Coke Oven Workers. J. Occup. Med. 14:621-29, 1972. operations. In addition, some local, 5. Maxumdar, S., Redmond, C., Sollec- u no 3E io spot ventilation (high velocity-low volume) is being considered for cer tain types of operations. In the interim, respiratory protection will be used to minimize the exposure poten tial. (Fig. 4). Exposed skin areas of employees The hygienist used ail his skills and tools to monitor and alert.* 1 on the potentially exposed population. ito, W,, Sussman, N.: An Epidemiolog ical Study of Exposure to Coal Tar Pitch Volatiles Among Coke Oven Workers. J. Air Pol. Cont. Assoc. 25:382-389, 1975. 6. Sexton, R.J.: The Hazards to Health in the Hydrogenation of Coal. 1. An Introductory Statement on General 1.7 13 12 11 16 13 12 11 U .4 .0 .8 .0 .8 .3 .1 are checked both before and after A better technique is needed to quan Information, Process Description, work shift, using an ultraviolet light tify exposures. and a Definition of the Problem. Arch. (long wavelength). Pre-work skin In the interim, every possible bit of Environ. Health 1:181-87, 1960. checks are necessary to be certain the information must be collected in the 7. Weil. C.S., Condra, N.I.: The Hazards I employees are not using lotions, etc. which fluoresce and therefore inter fere with the surveillance procedure. This technique is also used to survey tools and equipment leaving the event that a retrospective study must be done. If it is not, even the retrospectroscope won't help. Everything possible must be done to prevent a repeat of the morbidity-mortality ex to Health in the Hydrogenation of Coal. II. Carcinogenic Effect o( Mate rials on the Skin of Mice Arch. Envi ron. Health 1:187-194. 1960. 8. Ketcham, N.H., Norton, R.W.: The Hazards to Health in the Hydrogena controlled area as well as general area perience seen in the coke workers. tion of Coal. III. The Industrial surveys to identify areas contami REFERENCES Hygiene Studies. Arch. Environ. nated with PNA's for cleanup pur 1. Lloyd, J.W.: Long Term Mortality Health 1:194-208. 1960. pose. PROGRESS The medical surveillance tests being utilized are those which will lead to early detection of adverse Study of Steelworkers V.--Respira tory Cancer in Coke Plant Workers. J. Occup. Med 13-53-68, 1971. 2 Kawai, M , Amamoto. H , Harada, K.' Epidemiologic Study of Occupational 9. Sexton, R.J.: The Hazards to Health in the Hydrogenation of Coal. IV. The Control Program and the Clinical Effects. Arch. Environ. Health 1:208. 1960. health effects and represent the best Lung Cancer. Arch. Environ. Health 10. Personal Communication--H. Qazi to currently available tests. 14:859-64, 1967 N. E Bolton. R&S 142770 TY MARCH/APRIL, 1977 39