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50983
DOW CHEMICAL U.S.A.
PLAINTIFF'S EXHIBIT
DOW-161
TEXAS DIVISION FREEPORT. TEXAS 775*4 1
ENVIRONMENTAL HEALTH REPORT
ATMOSPHERIC CONCENTRATION OF ASBESTOS FIBERS WHILE GRINDING-ASBESTOS CONTAINING DERAKANE CELL COVERS ^
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FILE NO. M-134 nATF 11-30-72 AUTHOR B.S. Horvath
CHECKED DATE
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Summary
Concentrations of asbestos in the general atmosphere during grinding operations at Brazosport Plastics was found to be below the standards set in Federal regulations, but may be significant when considering possible carcinogenesis. Recommendations were formulated to reduce the atmospheric asbestos fiber concentration at a proposed Dow facility to go into operation at the Russellville, Arkansas Plant.
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N. E. Eberspacher A-1003
AN OPERATING UNIT OF THE DOW CHEMICAL COMPANY
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File No. M-134
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PROBLEM Environmental Health was asked to evaluate the asbestos hazard presented by the grinding of Derakane asbestos joints of Chlorine
Cell Covers.
CONCLUSIONS
1. Asbestos fibers are liberated by the grinding operation in significant quantities and found in the atmosphere throughout the building.
.2 The concentration of asbestos fibers found were as follows:
a. Breathing zone of man doing the grinding - ,84t/cc b. 20 ft. from grinding .86^/cc c. 90 ft. from grinding .21fZcc d. 120 ft. from grinding .17 /cc
Current government regulations allow no more than an 8 hour time weighted average concentration of 5 ^/cc.
3. The current regulations governing permissable exposures to asbestos are based upon the possibility of contraction of asbestosisli.Asbestos fibers, however, have also been shown to be carcinogenic. No dose/disease relationship has been established, so efforts must be made to reduce and eliminate, if possible, the workers exposures.
RECOMMENDATIONS
1. Grinding of asbestos reinforced Derakane should be minimized if possible.
2. Hand grinders should be equipped with dust collection devices.
3. Grinding should be done in an environmentally separate area
from the rest of the work area, to reduce exposure of other
employees.
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4. The man assigned to grind should wear an approved dust respirator.
5. Work clothing should be changed and washed daily.
6. Exposed employees should shower daily.
7. A suitable periodic medical examination program should be
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RECOMMENDATIONS .^continued)
arranged for employees exposed Co asbestos fibers.
8. Environmental measurements should be made annually to determine the adequacy of precautions taken.
DISCUSSION
Asbestos fibers inhaled over a prolonged period can cause a pulmonary disease called asbestosis. This fact has been recognized for many years by those involved in the production and sale of asbestos. During the last few years a .threshold limit value has been established for asbestos fibers in the atmosphere, the purpose of which is to prevent asbestos workers from contracting asbestosis. The current standard is 5 fibers/cc as recognized by the Federal Government. However, over the last few years respirable asbestos fibers have been recognized as being carcinogenic. A dose/disease relationship has not yet been established, so no standard has been published prescribing the acceptable concentration of asbestos fibbrs below which cancers will not appear.
For this reason exposures must be reduced to as low a level as is possible. This is done most desireably by reducing the exposure to the workers, and then providing protective equipment if the exposure cannot be eliminated.
This survey was made November 17, 1972 at Brazosport Plastics. One man, wearing a disposable respirator was assigned to grind the rough spots off a couple of cell covers. He:ground for 45 minutes while the two batches of samples were taken. During that time, visable dust could be seen in the atmosphere throughout the building. Photomicrograms reveal that most of the atmospheric dust is Derakane dust.
The recommendations are based upon the elimination of asbestos dust in a future Dow installation assuming that conditions are similar to those found at Brazosport Plastics. These recommendations are not intended to be applied to Brazosport Plastics. However, Brazos port Plastics should be informed of the potential hazards and what might be done to reduce the hazards of asbestos induced cancer.
A total of 4 samples were taken on Milliport 0.8 micron 47 mm AAWG membrane filters. MSA Monitaire portable vacuum pumps calibrated and used. Used filters were cropped into 4 grid sections and immersed
File No. M-134
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DISCUSSION (continued)
in 10% solution of diethyl oxylate and dimethyl phthalate on a slide, and then covered with a cover slip. When the membrane became trans parent counting was performed using 40X objective and a 12.5X eye piece, for a total magmafication of 500X. The eyepiece was equipped with a micrometer of 100 divisions 2.5 microne each.
Phase contrast illumination was used.
It should be remembered that the numbers given as the concentrations of atmospheric asbestos fibers is not to be considered as the absolute concentration, but the best-technique presently known. Tests have shown that this method produces numbers that are difficult to re produce from lab to lab, or microscopist to microscopist. However, it is the best technique we have.
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