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PLAINTIFF'S EXHIBIT
FFICE C P0 1
Biochemical Research Laboratory The Dow Chemical Company
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EXPOSURES TO ASBESTOS DUST ENCOUNTERED IN THE CHLORINE CELLS MAINTENANCE AREA, 295, 236, 137 AND 261 BUILDINGS
File: Date: By:
T34. 21-21-3 (K ) 9/9/69 R. A. DeGesero
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.
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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.
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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.
ST0000628
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 mppcf 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 reduce'd to within the proposed health standard of 2 mppcf by lowering concentrations of asbestos-containing dust in air, or approved respirators must be worn.
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" 1
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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.
RE COMMENDATIONS 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 protection until other means of lowering exposures can be found (.., ventilation improvement, changing work procedures, etc.), or some material can be substituted for asbestos which does not present the pulmonary hazards of asbestos.
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ST0000629
ST0000630
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6. All personnel who have occasion to use asbestos should be informed of the 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, May 14, 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 res Safety Department, 400 Building, ir R2090 cartridge respirators which : Respirators must be properly fitted
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r samples have been collected and evaluated using nicroscopy techniques. Concentrations of asbestosare expressed as millions of particles per cubic icf). Electrostatic precipitator samples have been
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ncentration (mg/m ) and crystalline composition (X-ray able 1 indicates that asbestos (serpentine) is the chief autuent.
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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 subclassified
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. ITRepair 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.
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asbestos rope and putty off the cement forms, or "rabbits."
Exposures An exposure describes the time-weighted eight hour average
concentration of asbestos-containing dust encoun
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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 =------ *____ E (cone, x time); =
480 min j - q
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)
295,236 295,236
295 295 236,295 295 295 295 295
Job Classification
Senior Cell Shop Mechanic Journeyman Cell Shop Mechanic Foreman, Crew Leader Plasterer Cell Maintenance "repair man" Cell Maintenance "set-up man" Cell Maintenance "weigher" Diaphragm Puller "Spares"
Time-Weighted Exposure to Asbestos
(mppcf)
1. 1 ' 1.1 1. 1 1.3 1.7 2.7 6.3 9.4 1.7-9. 4*
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Several other job classifications 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 time-weighting was dispensed with.
Building(s)
263 295,137
261 236 236 295,137
Job Classification
Resin Protector Fabricator Plant Mechanic Electrode Maker Cell Welder Special Welder Electrician
ST0000635
Health Standards A Threshold Limit Value (TLV) describes that eight hour time-
weighted exposure to asbestos a man can repeatedly encounter fox 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
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TLV guidelines, has formally proposed that the TLV be lowered to 2.0 mppcf to provide better protection for asbestos workers. Barring evidence to the contrary, the TLV of 2.0 mppcf will go into effect 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.
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
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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 V 7.3
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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 Ihe 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 scalesr 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.
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IN D U S T R IA L HYG IENE JO B A N A LY S IS
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T 3 4 .21-21-3
C hlorine C e ll Maintenance
Asbestos
295 8 /2 8 /6 9
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,_______________ UNIT-INDEX_____ _______________________ The time-weighted exposures encountered by the Diaphragm Puller, "Spares, "^eU'Msirite^'anbe^^efghlir'^ahd'CelllVTafnteharice "set-up man," all in 295 Building, are in excess of present or proposed TLV's for asbestos exposure (5. 0 mppcf and 2. 0 mppcf, respectively). A potential hazard to health exists at the time-weighted levels of exposure to asbestos encountered by the men in these job classifications. Recommendations to improve engineering and/or use of approved respiratory protection to lower the exposures to within the proposed TLV of 2. 0 mppcf have been made. All other job classifications-reviewed in 295, 236, 261 or 137 Buildings are within the proposed TLV. No foreseeable hazard to health exists at such levels of exposure to asbestos. General recommendations reflecting good practice in handling and storage of asbestos were also made.
ST0000646
DISTRIBUTION
N. Freeman, Industrial Hygiene, Freeport, TEXAS DIVISION J. E. Snider, Chlorine Cells Department, 295 Building F. Freudenmuth, Chlorine Cells Department, 261 Building C. W. Kline, Chlorine Cells Department, 261 Building B. B. Holder, M.D., Medical Department, 607 Building C. G. Kramer, M. D., Medical Department, 607 Building D. B. Morse, Safety Department, 401 Building F- Martinelli, Industrial Relations Department, 400 Building
5/26/71
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W. Snodgrass, Maint.. Service Admin., 49 pidg... (7/9/71,
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