Document M8LJ4jw28qp7mRYJ9wKrVbNa

Czf f:i(L TEXAS DIVISION FREEPORT. TEXAS 77541 ENVIRONMENTAL HEALTH REPORT Concentrations of asbestos in the general atmos'phere during the cutting of gaskets was found to be border line when compared to the Federal Regulation, but may be significant when considering possible carcinogenesis. Attached is a copy of the survey with recommendation to reduce the atmospheric asbestos fiber concentration. Oa* ui ro V> co cn i ' ..Distribution Billy Parrack File ; A-2431 AN OPERATING UNIT OF THE DOW CHEMICAL COMPANY File No. A24-173 -2- ST0652937 PROBLEM At the request of supervision, Industrial Hygiene was asked to evaluate the isbestos hazard presented by the cutting of gaskets in A-1876. CONCLUSION - --------- (1) "Asbestos fibers are liberated by the gasket cutting 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 cutting------- 4.03 f/cc (b) Breathing zone of man cleaning up area with broom---------------------------------------------------------------------------2.04 f/cc . (Note: Area has not been cleaned up for several days) (c) At top of stairway 15' from cutting table--5.44 f/cc (d) Breathing zone of man cleaning table off-----3.08 f/cc with broom and picking up material off floor with a scoop. . NOTE:(a)*(d)were taken when the area had not been cleaned for several days (e) Breathing zone of man doing the cutting------- .78 f/cc (f) At top of stairs 15' from cutting table------- 0 f/cc (g) In middle of shop downstairs during cutting- .12 f/cc (h) Breathing zone of man doing cutting----------------- .90 f/cc NOTE: (e) thru (h) were taken after the upstairs area had been cleaned up. Current government regulations allow no more than an 8 hour time weighted average concentration of 5 f/cc. The regulation also states that no employee shall be exposed at any time to airborne concentrations of asbestos fibers in excess of 10 fibers/cc. (3) The current regulations governing permissible exposure to asbestos-are based upon the possibility of contraction of asbestosis. 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. File No. A24-173 -3- ST0652938 RECOMMENDATIONS (1) The gasket cutting device should be equipped with dust collection devices. .(2) Cutting of gaskets should be done in an environmentally seperate area from the rest of the work area, to reduce exposure of other employees. (3) The man assigned to cutting gaskets shall wear an approved dust respirator. (4) Work clothing should be changed and washed daily. (5) A suitable periodic medical examination program should be arranged for employees exposed to asbestos fibers. (6) Environmental measurements should be made annually to determine the adequacy of precautions. 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 thd 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 efforts, must be made to reduce and eliminate the worker's exposure. For this reason exposures must be reduced to as low level as is possible. This is done most desireably by reducing the exposure to the workers, and then providing protective equipment if the v exposure cannot be eliminated. A total of 8 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 in 107* solution of diethyl oxylate and dimethyl phthalate .on a slide, and then covered with a cover slip. When the membrane became transparent counting was performed using 40X objective and a 12.5X eyepiece, for a total magmafication of 500X. The eyepiece was equipped with a micrometer of 100 divisions 2.5 microne each. Phase contract illuminatinn was used File No. A24-173 -4- DISCUSSION (continued) 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 reproduce from lab to lab, or microscopist to microscopist. However, it is the best technique we have. 6C6ZS901S S&LP bbs 4-19-73 7 - ' --*y - I File No.. A24-173 -5- ST0652940 ASBESTOS IN ATMOSPHERE DURING CUTTING OF ASBESTOS GASKETS Filter Factor = 154 SAMPLE TIME (min.) SAMPLE . RATE L/M TOTAL VOLUME (L) 13 2.57 22 2.69 33 2.69 43 2.57 10 1 min. 10 sec. 2.69 20 1 min. 10 sec. 2.57 30 3 2.57 40 3 . 2.69 50 -0- -0- 7.71 5.38 8.07 7.71 3.13 2.99 7.71 8.07 -0- Concentration = Total Fibers Total Volume *= Fibers * cc FIBERS 75 u PER SQUARE (1) 204 (2) 72 (3) 288 (4) 156 (10) 16 (20) 0 (30) 2 (40) 48 (50) 0 FILTER FACTOR 154 154 154 154 154 154 154 154 ' 154 t TOTAL FIBERS 31416 11,088 44,352 24,024 2464 0 308 7392 0 FIBERS PER cc 4.03 2.04 5.44 3.08 .78 0 .12 .90 * 0 / 11100 II-O'- - <?> ENVIRONMENTAL SURVEY SAMPLE RECORD datci J _ p. /J- OUlL OINC NO. 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