Document yp1pDEyn0BGrjo7yB5DN882X6

UFFICE COPY Biochemical Research Laboratory The Dow Chemical Company EXPOSURES TO ASBESTOS DUST ENCOUNTERED IN THE CHLORINE CELLS MAINTENANCE AREA, 295, 236, 137 AND 261 BUILDINGS File: T34.21-21-3 Date: g/9/69> By: R. A. DeGesero Signed Date 9,/ffep 7- 1- fe^ Supervision requested that the Environmental Research Laboratory survey and evaluate exposures to asbestos encountered by personnel during several operations In the Chlorine Cells area, 295, 236, 137 and 261 Buildings. CONCLUSIONS 1. The present TLV (Threshold Limit Value) for asbestos exposure is 5 mppcf (million particles per cubic foot). By 1971, barring ^ information to the contrary, the TLV will be lowered to 2 mppcf. The proposed TLV should be observed. $1006724 RESTRICTED: for use within The Dow Chemical Company only. ST006725 2 2. The northern end of 295 Building (cell repair and screen making) is an area of potential asbestos exposure. The southern end of 236 Building (chipping and cell repair area) is an area of potential asbestos exposure. Other buildings reviewed in the Chlorine Cell Complex (261, 137) lack significant potential for asbestos exposure. 3. In 295 Building, personnel in the Job classifications Cell Maintenance' Man and Diaphragm Puller receive time-weighted exposures to asbestos in excess of the present and proposed TLV's for asbestos (5 roppcf and 2 mppcf, respectively). The time-weighted exposures for these Job classifications are Diaphragm Puller -- 9. 4 mppcf Cell Maintenance "weigher" -- 6.3 mppcf Cell Maintenance "set-up men" -- 2.7 mppcf These exposures are unacceptable and must either be reduced to within the proposed health standard of 2 mppcf by lowering concentrations of asbestos-containing dust in air, or approved respirators roust be wofcn. 4. "Spares" in 295 Building are receiving time-weighted exposures of 1. 7-9. 4 mppcf, depending on whom they substitute for. The yearly average time-weighted exposure is 5.0 mppcf, assuming "Spares" 3 substitute equally for the Diaphragm Pullers, Set-Up Men, Repair Men and Weighers ih the course of a year's work. J'his^exposnrea ia unacceptable .and must.either.be reduced to within the~prbpdse'd health'standard of 2 mppcf by lowering concentrationa' of asbestos-conlalnS^ dust in the air, or approved dust respirators must be worn. 5. Personnel in 295 Building who are receiving time-weighted exposures within the proposed TLV of 2 mppcf include: Senior Cell Shop Mechanic Journeyman Cell Mechanic Foreman, Crew Leader Cell Maintenance "repair men" Plasterer 1. 1 mppcf 1.1 mppcf 1.1 mppcf 1.7 mppcf 1. 3 mppcf No health hazard is anticipated at these time-weighted levels of exposure to asbestos. ST006726 6. The Liquid Chlorine Operator, Assistant Operator and Hydrogen \ Operator in 295 Buitding can rec eive exposure to asbestos during a daily mixing operation. Based on concentrations found to be typical of mixing operations, no hazard to health from asbestos exposure is anticipated in light of the brief exposure time (at most 20 minutes per day). . ST006727 4 7. The following job classifications in 236 and 137 Buildings were examined for potential asbestos exposure: Plant Mechanic (295, 137 Buildings), Electrode Maker (261 Building), Resin Protector Fabricator (236 Building), Cell Welder (236 Building), Special Welder (236 Building) and Electrician (295, 137 Buildings). Asbestos exposures encountered by personnel in these classifications are small, and asbestos is not used in their work areas to any great extent. No hazard to health from asbestos exposure is anticipated for personnel in these job classifications. RECOMMENDATIONS 1. Personnel in the Chlorine Cells area who are currently receiving time-weighted exposures to asbestos-containing dust in excess of > 2.0 mppcf should be required to use approved respiratory'protectibn until other means of lowering exposures can be found (e.., ventilation improvement, changing work procedures, etc.), or some material' % can be substituted for asbestos which does not present the' pulmonary hazards of asbestos. 82^9001S M 5 2. Bags and drums'df asbestos should not be allowed to release asbestos fibers to the room air. If possible, asbestos should be weighed out and handled within a suitable exhaust hood. Bags and drums should be kept sealed and covered when not in use. 3. Supervision should request asbestos manufacturers use packages which do not allow leakage of asbestos. The burlap bags allow visible amounts of asbestos to escape from the bag when bags are jarred or placed near open doors, etc. 4. The practice of sitting on bags of asbestos in 295 Building should be discouraged. Fibers of asbestos were seen to leak out of the burlap bags when men sat on the bags. 5. Good housekeeping is essential in safe handling of asbestos fibers. >. _ Spills should be cleaned up at once._ Vacuum cleaning is preferred to sweeping with a broom. Supervision should determine whether an industrial vacuum cleaner is feasible in 295 Building or insist that f prior to broom sweeping the spills be thoroughly wetted with water to minimize dustiness. I ST006729 6 6. All personnel who have occasion tojuse asbestos should be informed ofjthe hazards of the material and learn correct procedures^for handling asbestos fibers so as to prevent high dust levels. An educational effort concerning use of approved* respiratory protection should be undertaken or continued, especially in areas of major exposures. 7. Any upgrading in ventilation, procedures, or handling of materials should be evaluated by the Environmental Research Laboratory to ascertain the effectiveness of such changes in terms of lowering exposures to asbestos dust. PRESENTATION OF DATA A total of 36 breathing zone impinger samples and 3 electrostatic precipitator samples were collected in 295 Building on May 13, Mays14, May 15, and May 27, 1969. Three breathing zone impinger samples were collected in 236 Building on August 4, 1969. The enclosed Floor Plan shows sampling points in 295 Building. *U.S. Bureau of Mines approved respiratory protection available at the Safety Department, 400 Building, include the "Dustfoe" 66 and Suregard R2090 cartridge respirators which remove the respirable range of dust. Respirators must be properly fitted. FLOOR PLAN OF CELL MAINTENANCE AREA (295 BUILDING) ST006730 8 Impinger samples have been collected and evaluated using standard light-microscopy techniques. Concentrations of asbestoscontaining dust are expressed as millions of particles per cubic foot of air (mppci). Electrostatic precipitator samples have been analyzed for concentration (mg/m^) and crystalline composition (X-ray ^diffraction). Table 1 indicates that asbestos (serpentine) is the chief crystalline constituent. > ST00673I 9 ST00673R 4 C e4 o. Eu 4 co 2 <4oa *0 N1 O * o in *N0O1 2o 8 a 2*uon>*. s c4 C " 3 4 - 2 a E 4 4 gfl <8 CO c4 3 4 aoco 4 mH tt1) imf * o w4 mi xu44 4 4UV 2 u4 & a 4 E eoc 4 C4 ion 2 & Xo3 E L c2 .2S *O- -- CO CO CO _E S4 > bo bo bo EEs 2Co -~Qc-frl U O - t- o r- o V 4a 4c a aoa o 4 X E 4 X4 L4i 4> 9 >O a <E40 < 2 m *m in H ou ini ot 4 4a 4a 5 X a 2 ou a E 4 CO O 2u E ^a44 4O a E4 a 4 5X *oa 4H 4 44 A 3a 24 > oA uav 4 C V C 8 ca e* Sc +c*d 2 x 4 &2 140 u 43 Of u 4 Z o bfl 2 Z*2o 23E ST006733 10 Job Evaluation An estimate of the effects on health of exposure to asbestos requires knowledge of both the concentration of dust and the length of time a man encounters such concentrations. Supervision and men define their activities by work areas to account for the eight hour day. The enclosed Industrial Hygiene Job Analysis tables list concentrations and exposure times for those Job classifications which show significant potential for asbestos exposure. The job classification Cell Maintenance Man has been subclassiHed into individual activities. The "weigher" in 295 Building weighs out asbestos and assists the Diaphragm Puller. "Set-up men" remove screens from the cement rabbits, transport the screens to the Diaphragm Puller, cut and install asbestos rope, mix, and plaster asbestos cement onto cells. "Repair men" may work In either 295 or 236 Buildings. Repair men's greatest exposure to asbestos is encountered during a chipping operation called "grubbing." Pneumatic chisels are used to rout dried cement, asbestos rope and putty off the cement forms, or "rabbits." Exposures An exposure describes the time-weighted eight hour average -\ concentration of asbestofr*containingdust encountered by personnel in ST00673li 11 the job classification being evaluated. Concentration and time of exposure vary independently of each other as the activity or location of work changes. Time-weighting integrates these two variables by summing the products of (concentration x time) for each change in area or activity according to the formula: n 8 hr time-weighted exposure s___ 1----- E (cone, x time)?0 480 min j 9 g for n different areas or activities. The following table lists the time-weighted exposures for several job classifications in the Chlorine Cells area. Building(s) Job Classification 295,236 295,236 295 295 236,295 205 295 295 295 Senior Cell Shop Mechanic Journeyman Cell Shop Mechanic Foreman, Crew Leader Plasterer - Cell Maintenance "repair man" Cell Maintenance "set-up man" Call Maintenance "weigher" Diaphragm Puller "Spares" Time-Weighted Exposure to Asbestos (mppcf) 1.1 1.1 1.1 1.3 1.7 2.7 0.3 9.4 1.7-9. 4* *5.0 average 12 Several other job classification* in the Chlorine Cells area were reviewed for potential asbestos exposure. Either there was no potential or very low potential for the job classifications mentioned below, so timerweighting was dispensed with. Building(s) 263 295,137 261 236 236 295,137 Job Classification Resin Protector Fabricator Plant Mechanic Electrode Maker Ceil Welder Special Welder Electrician ST006735 Health Standards A Threshold Limit Value (TLV) describes that eight hour time- weighted exposure to asbestos a man can repeatedly encounter for his entire work career with no adverse effect on health. The TLV is a time-weighted average. Exposures may exceed the TLV for brief time periods, provided such excesses are matched by periods when the exposure is correspondingly below the TLV. The present TLV for asbestos is 5.0 mppcf by impinger sampling techniques. The American Conference of Governmental Industrial Hygienists (ACGIH), which formulates the evidence to the contrary, the TL.V of 2.0 mppcf will go into etlect in 1971. . "Spares," the Diaphragm Puller, Weigher and Set-Up Men receive time-weighted exposures in excess of the proposed TLV. A potential hazard to the health of individuals in these classifications exists. The other personnel in Chlorine Cells are exposed to less than 2 mppcf (time-weighted), and no hazard to their health is anticipated. ST006736 DISCUSSION Asbestos concentrations vary considerably near the tanks in 295 Building. Depending on the operation, concentrations range from 0.5-40.8 mppcf. The following table lists the operations, concentration means and concentration ranges of breathing zone impinger samples near the tanks. Operation No. of Dust Concentration (mppcf) Samples Range Mean Sweep floors near bags Swab excess wet asbestos off screens Weigh out asbestos Slurry asbestos and caustic "Breaks" area 3 8 6 6 7 27.1-34.4 0.5-30.0 4.3-40.8 4. 2-34.2 0.5-19.8 29.8 16.3 15.1 13.4 7.3 14 ST006737 Concentrations of dust in the breathing zone caused by broom sweeping could be lowered if spills were wetted or vacuumed instead of being swept up dry. Use of suitable ventilation near the tanks would lower concentrations of dust in the breathing zone during the swabbing off of wet slurry and during slurrying of asbestos and caustic. Suitable ventilation at the scales would help lower dust concentrations in the breathing zone during weigh out operations. The concentrations measured in the breaks area would be lowered by adherence to both of the above suggestions. Dust levels in the breaks area averaged 7. 3 mppcf. This figure includes times when work has ceased at the tanks and scales. Data suggests that dust remains airborne in the breaks area and is added to as dust from other sources in the area (bags, spills) becomes airborne when men walk across spills or sit on bags. Concentrations of dust in the breaks area would be lower if spills were promptly vacuumed up, if bags were stored in a ventilated area and/or a better package were used, and men did not sit on burlap bags of asbestos. >