Document NayBeBQb5pawBpyb26qZOJNE

R & D REPORT \ DOW CHEMICAL U.S.A. V RESTRICTED: for use within The Dow Chemical Company only. artuent HER Industrial Hvgiene iftfrirfi7ii*-jkTW.kPORLT CrOfDE' HEH34.21-21-3(9) DATE SSOE3 December 4. 1975 ACCCwNT MO. PROBLEM NUMBER 8172 9082000 i EVALUATION OF ASBESTOS EXPOSURES TO UTILITY MEN OPERATING THE CHLORINE CELL DIAPHRAGM DEPOSITION PROCESS, CELL CC MANUFACTURING, 8S3 BUILDING, MIDLAND H3:I X Aw TmCB 3- SIGNATURE Si R. W. Bohl u ^E;iCER S SIGNATURE R. R. Lanener *aq- ft /z/s/7S / a/%/-zs DESCRIPTIVE SUMMARY WITH CONCLUSIONS: (In JjBdt in this spoct rgitnes to data books, and to earlier fttated reports, patents and publications*) Exposures to asbestos fibers by utility men working in 853 Building, Michigan Division, were evaluated while pulling chlorine cell diaphragms. Work area samples were also taken to estimate exposures to other personnel in the building. Measured concentrations were well within OSHA and the more stringent Dow time-weighted average ex posure limits. Peak concentrations were within ceiling limits. Ventilation and work practice changes are. recom mended to further reduce contamination. DISTRIBUTION: D. D. DeLine, ICPD, 47 Building H. V. Wait, Chloralkali, 851 Building R. W. McBay, Chloralkali, 855 Building C. D. Ingle, Chloralkali, 855 Buidling M. J. Miller, Safety-ICPD, 47 Building H. C. Scharnweber, MD, Medical, 607 Building M. Kelyman, Safety, 400 Building R. D. Olson, Industrial Hygiene Services, 607 Building H. L. Garrett, Analytical Services, 574 Building E. H. Blair, Health and Environmental Research, 2020 Bldg Industrial Hygiene Contacts (11) Central Report Index (5) to --I CD CD CD C*> CD Jpr FORM C-40340 STOOOI 305 2 PROBLEM The Industrial Hygiene Laboratory was asked to re evaluate asbestos exposures of workers in 853 Building, Michigan Division (Chlorine Cell Manufacturing Department). The operation involves drawing chlorine cell diaphragms by vacuum deposition from an asbestos slurry. CONCLUSIONS 1. Employees with the utility man classification, who work as the pulling tank operator, the helper and the crane operator, had asbestos exposures well within acceptable time-weighted average (TWA) limits for an eight hour day. 2. Air samples taken in work areas adjacent to the pulling tank indicate that exposures to all other personnel in the building were well within limits. 3. Ceiling limits were not exceeded during the dumping of dry fibers into the diaphragm slurry. 4. Housekeeping was good and the control of dust and loose fiber on the floor, in the gratings, and on equipment STOOOI 306 3 was noticeably improved. Improvements in ventilation and work practices would further reduce dust dispersion. Monogoggles, rubber gloves and protective clothing are worn to prevent exposure from accidental splashes or contact with the caustic slurry. Outer clothing is changed each day. RECOMMENDATIONS The local exhaust hood should be redesigned to improve the capture of airborne fiber at the points where the dust is generated. Employees near the tank should continue to wear res piratory protection during the dumping of the bags. Although ceiling limits were not exceeded in this study, the possibility of overexposure is avoided by using the mask. All other personnel should continue to stay away from the tank during this period unless protected by an approved respirator. Empty bags should be carried, not thrown, to the waste pile to stop causing this source of airborne dust. STOO0 I 307 4 4. Loose fiber should be removed from the. floor by vacuum cleaning after each cycle to reduce tracking fiber in the building. 5. An industrial hygiene survey should be carried out once every six months to help assure adequate monitoring and strict compliance to current and proposed OSHA (Occupa tional Safety and Health Administration) regulations and standards. STANDARDS The current asbestos exposure limit under OSHA reg ulations for an eight hour TWA basis is five fibers (over 5 microns in length) per cc of air sampled. The maximum peak concentration allowed is 10 fibers per cc of air. In July, 1976, the OSHA TWA standard will be reduced to 2 fibers per cc of air. The current Dow TWA standard is 2 fibers per cc air limit. A limit of 0.5 fibers per cc has been proposed by OSHA to replace the 1976 standard. OSHA requires a sampling interval of no greater than every six months for employees whose exposures to asbestos may reasonably be foreseen to exceed exposure limits. STOOOI 308 5 DISCUSSION Although exposures did not exceed TWA limits during recent surveys, we should monitor every six months to eval uate process changes, to assure strict compliance with current limits, and prepare us to meet the more stringent standards being proposed. Technical changes made since the last survey (HEH34.21-21-3(6)) have not changed the basic process. As before, the asbestos is received in plastic lined burlap bags and stored near the pulling tank into which the dry pulp is slurried with caustic solution. The bags are slit open by the pulling tank operator, carried to the edge of the tank and dumped in on top of the slurry surface about three feet down from the tank side. The recipe weight calls for a partial bag of asbestos which is manually weighed into a fiber pak and dumped into the tank. Visible dust rises above the tank as the dry asbestos is dumped. The operators attempted to minimize the dust and a local exhaust hood was used to capture some of the dust. This hood was only partially effective and modifications were recommended to increase the dust capture. The tank operators are required to, and do wear, approved respiratory protection during the handling of dry fiber and during the slurry preparation. Although exposure levels were within STOOD I 309 6 acceptable limits, the continued use of respirators is recommended to assure no overexposure to possible snoTt term peak concentrations. The deposition of the diaphragm onto the cathode assembly is essentially the same as described before. The slurry is controlled at a lower density and the deposition is done by vacuum pulling the slUTTy through the perforated steel cathode assembly three times instead of once, as before, to improve the quality. This has extended the cycle for one diaphragm from about 1 hour to 1 1/2-2 hours. The extra time does not increase exposure time to dry asbestos- The main exposure period to dry fibers is the beginning 5 to 15 minutes while weighing and dumping. Monogoggles, aprons and rubber gloves are used to avoid injury from any caustic that might splash out when smoothing down the diaphragm. OBSERVATIONS Appropriate protective clothing is available and was used. Disposable work clothing is provided for a daily change to avoid spreading contamination. Disposable clothing along with empty bags and debris are accumulated during the day and placed in plastic bags for disposal. At the end of the shift, the loose fiber around the tank is swept by vacuum using a flexible hose extension to the exhaust hood system. STOOO1310 7 There is some tracking of fiber during the day and the loose fibers should be vacuumed as soon as possible during each diaphragm cycle. During this survey, two men alternated between the pulling tank operator and the helper jobs. Normally, these jobs are not switched during a given day. Only minor variability between operators was observed. Both operators on the pulling tank threw the empty bags to an open disposal area about 10 feet away. This created observ able airborne dust. Empty bags should be carried rather than thrown and placed inside a plastic disposal bag to reduce airborne contamination. Housekeeping was very good and noticeably improved since the last survey. VENTILATION A local exhaust hood was used to help control dust and the exhaust from this hood is vented into the atmosphere through a filter. Figure 1 summarizes an evaluation of this hood using smoke tubes to observe the capture of airborne contamination. When placed cone face down, capture within 6 inches of the hood is reasonably effective. Capture underneath the hood appears to be effected to 18 inches down. The bags are dumped outside of this profile and much of the airborne fiber escapes to the work area. Measurements ST0001311 8 indicate blower capacity and duct transport velocity are adequate, but the hood configuration (cdnical) is poor, and should be replaced with a packaging type hood where air flow is limited to the direction where the dust is generated. A specific design will be worked out with plant supervision and installed to improve the dust capture. SAMPLING AND ANALYTICAL Breathing zone air samples were collected on 37 mm diameter, 0.8 micron pore size, membrane filters (in cassettes with open face). Three MSA, 8 hour (Monitaire) pumps were calibrated with these filters and were operated at 1.3 to 2.1 liters of air per minute. A Gast vacuum pump calibrated at 16.7 liters per minute was used to take breathing zone samples of the tank operator during the dusty part of the job. Work area samples were also taken with this pump to check airborne fiber concentrations away from the tank area and at the tank area during the wet part of the cycle. The MSA pumps, with tubing and filter, were worn by the operators during each diaphragm cycle. Fibers (over 5 microns in length and with a minimum 3 to 1 length to width ratio) on the filter were counted by the standard phase contrast microscopy technique at 430 magnification. Slide specimens ST 0001312 9 of the filters were prepared by the author under the super vision. of H. L. Garrett of the Analytical Laboratories, Michigan. Division. Counting was done by the author and by J. A. Jacoby both of the Industrial Hygiene Laboratory. Current analytical procedure for counting asbestos requires double counting. Gross differences in count are to be refereed by a trained microscopist. Both counts in this case were within 10% of each other in all but two samples and these were within 20%. The counts were averaged for the calculation of exposures. The data is filed with the orig inal data for industrial hygiene report number HEH34.21-21-3(9). RESULTS Table 1 shows the breathing zone and work area asbestos levels found. The highest levels did not exceed ceiling limits. As before, the highest airborne concentrations were found next to the tank during the handling of the dry fibers. Although current ceiling limits were not exceeded, ventilation and work practices should be improved where possible to further reduce dust escape. If the OSHA standard is lowered to 0.5 fiber per cc, the ceiling values will become more stringent. Table 3 shows the highest level found was next to the tank operator and was well under the excursion ceiling of 10 fibers per cc. This was only a potential exposure in that the operator STOOD I 31 3 10 . wore a respirator. Table 2 shows the TWA exposures for the three utility men who work on this process. All were well below the 2.0 fiber per cc air Dow Industrial Hygiene Guide (IHG). The calculations assume each job is covered by the same man for 8 hours. The pulling tank job shows the high exposure at 0.7 fibers per cc. OSHA is currently looking at 0;S fibers per cc as a possible standard. Should this standard become effective, administrative control, i^.e. alternating the 3 jobs between the three for more) men, would provide a method of meeting this 0.5 fiber per cc limit. Table 4 shows a possible TWA exposure if the jobs are alternated. Ft HOOD SURVEY DATA ST000i31 4 nCuTsHnDuPHSOEERK y v .BUILSIMG NUMBER 34.Z/-Z/-36)\ f?53 Hbab LOCATION, DE^ICHAftCN DATE. * TTPE Op HUUQ 10/10/75 kh orr -- Ln^^l Wlcvzahte "to ar-&A uJh&r^, cf^y ash&s~i-as T-tbes* is a handled . INTERNAL 5APPLE? EXTERNAL BAFFLE? CHEMICALS HANDLES iH THU rtOOJJ OtHERi HxoOsCgqTl CSNNECTEO 10 TnE SUE EXHAUST SYSTEM /V( /4cr6&s-tes sources te aiA astuukce bxruRMAu IU ihu n>U>o A/ttr'/^fcr/ &tr~ STATIC PDREIKSSIIUSRCE '' --- -- -/ ' //ogt'c: I --REMAA rRK..S. njg^ 1' ~&*</ "" CtfA U3Uj>//*/ ' * ~f-focJ-<=/e^j*$n ',s ^* *** good --Afi'/jO-* t/T-Jl*'. /^a Aooc/ sAovSe/ 6-t* 7-tstxejJ -Jo a Amrcfe/z/ j*cJ0Sot~a Fue.tn^ 'f'hA )^Cd r-fj-'js /ur&^r'/ns' ZfAs.r^s *2*** ai.>-^g/i*va. > /OO /5oRECOMMENDED MEAN FACE VELOCITY FOR THIS HOOD. - , F. P.M., DOOR OPEN. .IN. RECOMMENDED EXHAUST RATE FOR THIS HOOD C. F. M. ACTUAL FACE VELOCITIES HOOD FACE AREA DURING SURVEY EXHAUST RATE DURING SURVEY ZMAXIMUM OPENING: HEIGHT______ HAXIUIM 315 -3{.Q _sq. ft. fZ-O 0 C.F.M. MINIMUM 4?o F.P.M. MEAN 4oa *pu VARIANCE fl/lirutnum ffiMSpoj'i' VcJoe.f/-y ~3ooofpx Acrt-ual ~Tnx>lfp<tr"/ Vi/rc-fty -s't-5`2.00 FPn. IH., WIDTH ----------- IN. MAXIMUM HOOD FACE AREA SQ.FT. INSTRUMENT USED FOR AIR VELOCITT MEASUREMENTS __7~h ac'tfccLrt&Ma m 3 ORUC-IHJ PRINTED IUU.1>. R*it ^ J * >****~-- SERIAL NUMBER WTj, Pr- *P C3 -ct-c mC t--c2s o to pP too o tn u-i < o o ST000 I 3 I 5 rt--H| COM' c O to oH coc T a b le 1 . ASBESTOS TN AIR SAMPLES TAKEN AT CELL MANUFACTURING, 853 BUTLDTNG, OCTOBER 1 0 , 1975 b0 O P CO CO to H cd n a> Gp PP -H A* 02 CO r-< RS o c0 CL CO P tH 0) *U CL P 0) H rP O P r P * G P- P P O a> a> co P Hg * O o CL P * *H T3 AS a> p t--t CO H C g fl) (O 4J a p: g O P P H CO CO p R) 02 4* pp xt o o p 10 P P P <u o ^ ? P P. CO p. to to * >> CO o o - CO 44 O 'H p to O to H 6 4-> p ** COP CO CO CO 02 <p G Ctt c o i--v P P r-t 02 CD P to r- ri 0> *H O m H o ri P . r Pu a> a) P-p op C *cH e 6 >Ntn p P Ur* (0 C5 o g >s PO u a g C5 V) e o> p xp P XI P CO--i tfl*H p w opX- a> lwd -apj OPo ,G H p CL X m to Q> CD (D H H3 CU rC tHo) c: P T-t p*--- -- p"I /--X T~' 10 +* ri gn t-- ^ ts o rH p p P Xd C3 rC G * +J -tH CD S 1-r P H 'o e r*- O r-5 ea p oou P T-- P P P ac 0 C r c/) rH X P UO >*to C in p p p \__/ o to o , *-* 4-1 O ^O tp -- tij . CO C o (D M c ~ C C 0) w ~ p p CD <D C r-t C2 tO J-- i-i -m OP o o u O i--: o G p--i C2 * cc CM *-- C Er r-- <~v o ^ C r- O U C 50 P in cd G C. tr. tJ CO bJ w M M C. O <n g- S O P O p - in ap ec*~ c to O to G CO to to c raws 50 C P p rw r* v GC Tc-; -- o ^ o cd cc f- w c: 2 (0 -- *X3 P xz CO p tn 'G ra f-t f- G P -- P u P c p c; CD -- -- c_ cz zz ~ u V) ^ E. O k: C to p cs a a c) PG C2 L. P O p 0) o f-l^ P0m* ^ 4- ra O O--c S cc C3 T--! CC P P 2 O CC PC o P o g S'P C/3 w 0) rPH j eOj C4 cn P tc c o r-i G H to O P 'J n in o4>o to p (D ./ P H p O -H G cc m to CM G -cr O o CM G G ST0001316 C CM A s b e s to s .in !.s~I; . tn r--\ o cn 0 p ppt H rr H 0 r-t U X * o at 0 CO PG G *-! G 0 0 /--> tn G i-G CO Ci V___/ w tn r-t SH HG Pr-t cc AG JS C P r*-- G 0 0 tn co tn g GP X P 'O p c 0 p 0 cm o r-t *H P SC G r-t u G r- r-t ,ac* r-t G 0 H U 'O gm H o P 0 p /--V <p cn G0 *> ,iC P P T3 C*H G P a tn P <--o* r C cc G 1--! pp tn p GG 0 C* pp P tn OP * cc ro -ih P com G *^r rl W r-t rH P o C *H G G X o p. I- t) M" OG CM Oc P T--1 iH'H ; tf) 0 0 V) V. -- p o^ X Ai CL. irj -O =0 0 C G -- t_, c !/>"* GG P tn tr. C n O ^5 G CJ +J J- 0C tn tn g - 3 c P P GG - e2 G H 0 0 0. S Vi ^ec h ra -X 0 PG G G0 O tn E OG3 CO CC - S to -- g c cs (o +J fi = <0 u tn o Cu X 0 -< *0 G3 e: o c o n cc X X GG -- "G P PP tn p GO Ci -- c )--t p r? > CO ao -H 0 P H e H r-t 0 P tn O cx. a> bo C o u < 55 c c C3 *o C5 oz. CJ oo CT1 ! -vrr.. STOOOI 317 Table 2. TWA EXPOSURE TO ASBESTOS BY THE UTILITY MEN ON THE CHLORINE CELL CATHODE DIAPHRAGMING OPERATION, 853 BUILDING NOTE: Three utility men perform this operation. One man operates as pulling tank operator, one as helper and the third as crane driver. Three diaphragms are deposited during the 8 hour day shift. The operators can alternate between jobs but normally do not, and the calculations assume the men do not switch jobs. A. Utility man as diaphragm pulling tank operator Activity Time during Exposure* Time x day fiber/cc exposuri Pulling tank operation 560 0.90 324 Other work and misc. 120 -o __ 0 480 324 TWA exposure = 342M4 -' 00,77 fibers/cc air sampled Dow IHG = 2.0 Utility man as helper Helper on pull ing job Other work and misc. 360 0.38 120 ~0 480 TWA exposure = T1*M^ 7 -- n'3^ fibers/cc air sampled Dow IHG = 2.0 137 0 137 STOOD 1318 Table 2. CONTINUED C. Utility man as crane operator Activitv Time during Exposure day fiber/cc Operating crane and helping during cycles 360 0.24 Other work and misc. 120 ~0 480 TWA exposure = =0.2 fibers/cc air sampled Dow IHG = 2.0 Time x exposure 86 _0 86 STOOO1319 Table 5. PEAK EXPOSURE TO AS3EST0S BY THE UTILITY MAX CN THE CELL CATHODE DIAPHRAGMING OPERATION, 855 BUILOING NOTE: In this study and in past studies, the utility man working as the pulling tank operator has the greatest exposure potential. He wears approved respiratory protection during the time dry asbestos is being handled to assure safety. ActivitY Weighing dry asbestos fiber into a fiber pak and dumping this fiber pak plus several bags of fiber into the pulling tank. (This operation takes about 10 minutes.) Dow ceiling exposure limit Exposure, fibers/ml air 4.25 10.0 ST0Q0I320 Table 4. POSSIBLE TWA EXPOSURES BY UTILITY MEN IF THEY ALTERNATE JOBS DURING THE SHIFT* Activity Pulling tank job Helper Crane operator Other Maximum time 120 120 120 120 480 Exposure 0.90 0.38 0.24 ~0 Time exposi 108 46 29 0 183 TWA exposure possible = = 0.4 fibers/cc Current Dow IHG and OSHA standard as of July 1976 = 2.0 Proposed NIOSH criteria (not yet approved) = 0.5 *1. Assume no respirator worn at pulling tank. 2. This administrative control may be advisable if government TWA standards are dropped to 0.5 fibers per cc of air.