Document kazDqBERwrdRZ4eDEKqby97G0

THE DOW CHEMICAL. COMPANY ^' NUMld RESTRICTED fO* USE or DOW EuPLOTtlS ONLY NBH24.21-21-3 f5) ACCT: 8172 MIDLAND. M 1 C H 1 CAN snarrsTiT-------------------------------------------------------------------------------------------------------------------------------------------------- CAT! DIG Chemical Eiolocr/ Research Aucust 3. RiQtLi* mchRCR M. F. Stevenson lit 9082000 1973 n i EVALUATION OF ASBESTOS EXPOSURES, CHLORINE CELLS PLANT, S3! ar.c 295 JLI CN i BUILDINGS tj "j INFORMATIVE SUMMARY WITH CONCLUSIONS nVIj The pulping operator's exposure to asbestos fibers was eval Si uated during the mixing of asbestos at the Chlorine Cells Plant, 851 Building. Background readings were taken at 293 o 5 Building after several cells had been through the water jet cleaning operation. Time-weighted average exposures to asbestos are within acceptable levels. "I o* Recommendations include the continuing use of respiratory 85 protection during handling of dry asbestos and the use of . "wet suits" to cut down on the transport of dry asbestos <M ^ fibers into the lunch and control rooms. Samples taken by M. F. Stevenson and G. H. Flores, dQ-ti-JLREVIEWED BY g-s-73 ' I ISSUED TO S. F. Vansumeren, Chlcralkali Plant, 851 Building C. W. Kline, Chloralkali Plant, 851 Euilding H. R. Goodwalc, Chlcralkali Plant, 851 Euildinc R. R. Lancner, Industrial Hygiene Services, 607 Building 3. B. Holder, M.D., Medical Department, 507 Euilding M. Kelyma.n, Safety Department 400 Building Central ,Report Index (5), 556 Buildinc 0) /-/*'7$ cda o o o CD UD cn ^ i u-juu^b^ PROBLEM The industrial Hygiene Section of DIG Chemical Biology Research was asked to evaluate the exposures of Utility men cc asbestos fibers during preparation of slurry in the pulping operation of chlorine cells. CONCLUSION'S AND RECOMMENDATIONS 1. During the handling of dry asbestos prior to mixing, peak exposures exceeded the Threshold Limit Value of 5 fibers/ml and approached the maximum allowable of 10 fibers/ml. (See Table 1): The Utility man's timeweighted average exposure to asbestos was within accept able levels. 2. The men mixing the slurry should wear respiratory pro tection during this operation. 3. Wearing of wet suits, "rain suits", should continue to cue down on the transport of dry asbestos fibers into the lunch and control rooms. 4. When washing down the work area asbestos fibers tend to cling to the pipes just below the grating but above 2- - ST0000963 -3- grounc level. Ir. time this m.ighc present an accumulated problem and unnecessarily expose those working below, especially when the fibers are dry. 5. Containment and improved cleanup systems at the bin are presently being evaluated by supervision. They have a plan to prevent asbestos fibers from falling to the pipe beneath the grating. Some thought is also being given to the containment of asbestos fibers when scooping into the mixing buckets. 6. Asbestos levels at 295 Building on the date sampled were acceptable. PROCESS Asbestos is brouchr up to the second level by way of life truck. These bags are then opened and dumped inro a storage bin wich some evidence cf fibers becoming airborne. This asbestos is dumped into two different storage bins depending on the grade of asbesuos needed. After the bins are filled, buckets are filled about half full and water S tOO 00964 -4- mixed to get a slurry. The buckets are then taken to the chlorine cells and emptied. The number of buckets used depends on the number and severity of the leaks. SAMPLING AND ANALYSIS Breathing zone air samples were collected on millipore filter cassette (0.8 micron pore size) at a sample rate of about 2.0 1pm using MSA personnel sampling pumps. The fibers on the filters were counted by the standard phase-contrast microscopy technique at 450 magnification by the Midland Division Microscopy Laboratory (AL #59696). PRESENTATION OF DATA Table I shows the Utility workers peak exposure to asbestos fibers during the pulping operation. One of these samples was not within an acceptable level based on present standards. Table II shows a background reading in 295 Building after several cells had been through water jet cleaning. Levels seen here were within an acceptable range. <510000965 -5- Table III shows the Utility workers exposure to asbestos fibers based on an eight hour day when doing pulping and laboratory work. The time-weighted average and peak exposures were within acceptable levels based on the present standard. ^iuuuu^bb TABLE I CHLORINE CELLS PULPING OPERATION, 851 BUILDING Exposure to Asbestos Fibers Operation Number of Samples Asbestos Concentration Ranae Averace Scoop-nvix to slurry Scoop-mix-dump into chlorine cells 3 2.69-7.86* 1 0.19 4.74 0.19 *Fibers/ml. 6- - ST0900967 TABLE II CHLORINE CELLS CLEANING, 295 BUILDING Background-Levels of Asbestos ODeration Number of Samples Asbestos Concentration Range Average Water Jet cleaning area and background. 2 0.56-1.02* 0.79 *Fibers/ml. 7- - ST0000968 TABLE III CHLORINE CELLS PULPING OPERATION, 851 BUILDING Exposure to Asbestos Fibers Operation A Time per . Eight Hour Dav (min.) Unload-scoop-mixdump slurry. Unloading Cleanup Laboratory - Lunch and Breaks 242 20 15 ~143 60 B Average Cone. (Fibers/ml) AxB 480 5.87 0.23 1.29 -- 0.69 0.01 0.04 ' 0.00 0.00 TIME-WEIGHTED AVERAGE 480 THRESHOLD LIMIT VALUE* MAXIMUM ALLOWABLE CONCENTRATION 10.0 0.74 5.0 Threshold Limit Value (TLV) - The time-weighted average concentration to which it is believed that most people could be exposed daily without adverse effects. 8- -