Document J3vM6DEdKjBB1m66KEb2Mg6gB

NBH34.2 1 -2 1 -3 (5 ) J7 7/ THE DOW CHEMICAL COMPANY '^ Will MIDLAND, M 1 C N 1 SAN tlfTBICTID orroa ina bow imployiii only NBH34.21-21-3(5) ACCT: 8172 hputtuvt 1 11 .............. .. ........................ -- ... -- bXTI DIG Chemical Biology Research August 3. 1973 iTBcrni uoizm M. F. Stevenson TITLI ' 9082000 EVALUATION OF ASBESTOS EXPOSURES, CHLORINE CELLS PLANT, 851 and 295 BUILDINGS INFORMATIVE SUMMARY WITH CONCLUSIONS The pulping operator's exposure to asbestos fibers was eval uated during the mixing of asbestos at the Chlorine Cells Plant, 851 Building. Background readings were taken at 295 O 5 Building after several cells had been through the water jet cleaning operation. Time-weighted average exposures to asbestos are within acceptable levels. 0 * Recommendations include the continuing use of respiratory protection during handling of dry asbestos and the use of "wet suits" to cut down on the transport of dry asbestos fibers into the lunch and control rooms. Samples taken by M. F. Stevenson and G. H. Flores. REVIEWED BY g-s-73 mmp to S. F." vansumeren, Chloralkali Plant, 851 Building C. W. Kline, Chloralkali Plant, 851 Building H. R. Goodwald, Chloralkali Plant, 851 Building R. R. Langner, Industrial Hygiene Services, 607 Building B B. Holder, M.D., Medical Department, 607 Building M. Kelyman, Safety Department 400 Building Central^Rejjort Index (5), 566 Building 0) /J-/e -7$ dda -or O O CO IN> --I ^ 398113 ST00327 I 3 PROBLEM The Industrial Hygiene Section of DIG Chemical Biology Research was asked to evaluate the exposures of utility men to asbestos fibers during preparation of slurry in the pulping operation of chlorine cells. CONCLUSIONS AND RECOMMENDATIONS 1. During the handling of dry asbestos prior to mixing, peak exposures exceeded the Threshold Limit Value of 5 fibers/ral 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 cut 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- 398114 ST00327 IU -3- ground level. In time this might 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 pipes 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 brought up to the second level by way of lift truck. These bags are then opened and dumped into a storage bin with some evidence of fibers becoming airborne. This asbestos is dumped into two different storage bins depending on the grade of asbestos needed. After the bins are filled, buckets are filled about half full and water 398115 ST00327I 5 -4- raixed 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 deeming. Levels seen here were within an acceptable range. 398116 ST00327 I 6 -5Table 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. 398117 STG0327 I 7 TABLE I CHLORINE CELLS PULPING OPERATION, 851 BUILDING Exposure to Asbestos Fibers Operation Number of Samples Asbestos Concentration Ranqe Averaqe Scoop-mix to slurry Scoop-mix-dump into chlorine cells 3 2.69-7.86* 1 0.19 4.74 0.19 Fibers/ml. -6- 398118 ST00327 I 8 TABLE II CHLORINE CELLS CLEANING, 295 BUILDING Background Levels of Asbestos Operation Number of Samples Asbestos Concentration Ranee Averaae Water jet deeming area and background. 2 0.56-1.02* 0.79 Fibers/ml. -7- 398119 ST00327I 9 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 TIME-WEIGHTED AVERAGE 480 THRESHOLD LIMIT VALUE* MAXIMUM ALLOWABLE CONCENTRATION B Average Cone. (Fibers/ml) 5.87 0.23 1.29 -- __ 10.0 AxB 480 0.69 0.01 0.04 0.00 0.00 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- 398120 398121 ST 0032720