Document ExrLOLY4Grgd7Q0eqD7ppwYQb

/V' F,*<t ,> . L Asbestos Exposure During Naval. Vessel 009 OveriSiM'M , WILLIAM X. MAKR Medical Department Lang Beach Naval Shipyard, Long Beach, California ( A study among insulation -workers in a shipyard has revealed several men on disability compensation and one death due to asbestosis. Exposures occur during the fabrication and installation of asbestos insulations and during, removal of insula tion for repairs or overhaul of ships. X-ray examinations are not adequate for con trol as cases usually take a minimum of seven years to develop. Problem iron, nickel, manganese, or aluminum often THE LONG BEACH Naval Shipyard In-. sulation shop has 60 to 80 employees working primarily aboard ship applying in sulation containing asbestos to the steam power plants, Five employees, averaging 15 years exposure, have retired on disability compensation due to asbestosis. One em ployee, after 10 years employment as a pipecoverer and insulator, received disabilitycompensation for seven years prior to his death in 1962. Extensive physical examina tions and autopsy reports leave no doubt his death was due to asbestosis. He worked most ly on farms and in restaurants before his employment in the shipyard and denied any previous employment in a dusty trade. Breathing asbestos fibers, ^usually over a period exceeding 10 years, causes this insidi ous industrial disease.1'2'3 A non-productive cough and progressive shortness of breath that can . lead to disability are the most strik ing symptoms.4'6 This report covers: (a) material used, (b) working environment, (c) fiber counts, (d) x-ray findings, (e) discussion, and (f) sum mary. Material ' replacing part of the magnesium. The fibrous form of amphibole has four principal vari eties, amosite, anthophyllite, tremolite, and crocidolite. These four are various silicates of iron, calcium, magnesium, and sodium. The replacement of one element by anoth er in varying proportions is a unique charac teristic of asbestos causing a change in its physical properties. For example, machinery crushes chrysotile into fine soft silky-feeling fibers which are strong, flexible and can be woven into cloth. Amosite, which comes from South Africa, has long coarse fibers suitable for a blanket-type of insulation ma terial. Amosite has been used in large quan tities on naval ships since before World War II. Other than amosite, the amphibole min eral type of asbestos is weak and brittle. Most authorities believe that all types of asbestos can cause asbestosis.7 Medical sci ence has not conducted sufficient research to determine the possible different effects of the mineral or which variety is the most hazardous. Employees in the insulation trade also use fiberglass, magnesia, diatomaceous earth, and other inert substances that can complicate air sampling and the exposure hazard. Ship Asbestos is a commercial name applied board insulators use about ten different types to several varieties of fibrous minerals. These of insulation material containing different varieties are two distinct mineral groups, ser varieties and a varying quantity of asbestos. pentine and amphibole, that differ consid Table I gives a list of material used in ship erably in composition and physical proper board insulation and its composition. The ties.3 Chrysotile. the fibrous form of ser table also shows the percentage of time the pentine. comes from Canada and constitutes employee works with. the material and his about 95% of the total world production of exposure in millions of particles per cubic asbestos. It is a magnesium silicate with foot. 264 h. California :d several men on sures occur during removal of insulaadequate for con- nese, or aluminum often : magnesium. The fibrous has four principal vanophyllite, tremolite. and :our are various silicates agnesium, and sodium, of one element by anothtions is a unique characcausing a change in its For example, machinery itr ' re soft silky-feeling m. -iexible and can be Amosite, -which comes has long coarse fibers st-type of insulation ma)een used in large quansince before World War site, the amphibole min s weak and brittle, relieve that all types of isbestosis.7 Medical sei zed sufficient research to ble different effects of ch variety is the most nsulation trade also use diatomaceous earth, and es that can complicate exposure hazard. Shipibout ten different types ai containing different ng quantity of asbestos, f material used in ship-L its composition. The percentage of time the t the material and his of particles per cubic Material (Used aboard ship by pipecoverers and insulators) 1.100% Amosite asbestos blanket Installing Removing 2. 85% Magnesia and 15% amosite asbestos blocks and pipe sections Installing Removing 3. Calcium silicate and 10% amosite asbestos blacks and pipe sections Installing Removing 4.100% Chrysotile asbestos filler and binder Installing Removing 5. 15% Chrysotile and 85% rock wool filler and binder Installing Removing 6. 80-95% Chrysotile asbestos cloth Removing 7. Fiberglass Installing Removing Percentage of worldng time aboard ship (with eadi rarely . 3.0 Exposure Concentrations (length of exposure time varies from minutes to hours) particle range in microns fiber range in 2-5 mppef 5-10 mppef 3-60 mppef 1.4-3.0 Installed damp 1.6-2.0 0.5-S.0 38.0 1.5 1.4-6.0 0.8-10 0.1-0.4 0.7-2.0 0.1-1.8 tr.-l-2 42.0 2.0 0.9-2.8 0.4-1.7 0.2-8.0 0.4-0.9 trace trace 1.5 mixed as cement and applied wet 0.5 0.9-4.9 0.9-1.6 trace 1.5 . mixed as cement and applied wet 0.5 O.S-4.7 0.7-1.7 trace S.0 0.5 1.0 rarely 0.3-1.8 0.2-1.9 0.2-1.4 0.5-2.0 trace trace Working Environment These employees, known as pipecoverers and insulators, face a potential exposure to asbestos fibers in the insulation shop and on board ship. Employees in the shop make pads shaped like small pillows for easy installation and removal from shipboard fittings, control valves, and pipe joints. A bolt of asbestos cloth is on a roller at the end of the layout and cutting table. Directly over the bolt a water spray system allows water to dampen the cloth as an employee draws it on the table. The employee measures and marks the material into appropriate sizes and cuts it with a rotary electric hand cutter. An other worker then stitches the cloth on a power sewing machine and passes it to an other table where fiberglass is cut to size and stuffed into the opening. Finally, an employee closes the pad by sewing, trims it with a pow er cutter, and attaches rings to aid in the installation aboard ship. The cloth remains damp during the work process making dust control methods relatively easy in the shop. General exhaust ventilation operates contin ually, assisted by large doors and windows allowing for cross-ventilation. ' Aboard ship pipecoverers and insulators perform a great variety of installations in most compartments, especially in the firerooms and enginerooms. Several of these tasks are shown in Figures 1, 2 and 3. These men wire insulation block and insulation pipe sections in position around machinery and pipe. They make the surface smooth first by mudding with 85% magnesia plaster and then wrapping with asbestos cloth glued in position with a fire retarding waterproof ad hesive. The amosite blanket, rarely used now, was generally used rather than preformed blocks and pipe sections until 1962. Em ployees apply rock wool mud to this amosite blanket followed by portland cement and 266 May-lmir. /<?54 Figure 1. Removing insulation during over haul. asbestos cloth to form a smooth finish. They apply glass sheets to ventilation ducts and wrap it with fiberglass or asbestos cloth. These men wrap fiberglass around fittings, control valves, and pipe joints, then attach the pads from the shop into position. During ship overhaul, repair, and remod ernization, pipecoverers and insulators re move all the. various types of insulation they have applied. As shown in Table I, this small portion of time spent in removing excessivelv drv insulation gives a high exposure to asbestos dust. Adequate ventilation for pipecovers and insulators is rarely possible with our present ventilating system, which consists of 3,600 cfm exhaust fans with connections for four 5-inch flexible ducts. These portable exhaust fans are usually placed on the main deck and the ducts routed into the work area. The flow at each exhaust-duct entrance varies from 800 to 1500 lfm depending on the dis tance from the exhaust fan to the work process. This present exhaust system designed especial!)' for welding and burning work is not adequate for our pipecoverers and insu lators because their work processes and work positions vary. Dust control by use of water during ship board work appears to be practical only dur ing application of amosite. a material seldom applied in our shipyard because of the ex cessive dust it causes during removal. The best protection for these employees is to avoid careless creation of dusty conditions by the use of damp material when possible, and the wearing of dust respirators constantly. Ficure 2. Applying filler and binder. Figure 3. Sawing pipe sections. \ May-]mil. 7954 1 of time spent in removing ex insulation gives 0 high exposure List. ventilation for pipecovers and rarely possible, with our present rstena. which consists of 3.600 fans with connections for four s ducts. These portable exhaust lip placed on the main deck and .iced into the work area. The 1 exhaust-duct entrance vanes 1500 Ifm depending on the disthe exhaust fan to the work present exhaust system designed welding and burning work is for our pipecoverers and insu: their work processes and work >1 by use of water during shipppears to be practical only dur- n of amosite, a materia) seldom ir shipyard because of the ex-' t causes during removal. The >n for these employees is to creation of dusty conditions by nr -ateria] when possible, and f c respirators constantly. h Sawing pipe sections. jntJu'trial Hygiene Journal 267 v' ! '^ l T T4 y - 'N . * S.' V f"4 `i ' > ~ r: r>v 7 *4f . .f-' .'X . >> .T r-V-s.. N* /* fc. ' ' ui u - '< Sr ftT; '';'v jr: % J k V/i ^ *1 .V- V . *- . V V-rt . : . ! -v.- -i ~{r. 14 V 4 . 1 - '1 v. 1 Figure 4. Photomicrograph of dust sample taken during insulation, removal, Small squares are 20 microns. . V W'.f'l* - .k 4 V\ e* A 7. - 4. ^4 ..... T < .! - 1 i . _ " :* - i - r. T( * 1-- . .. Figure 5. Photomicrograph of dust sample tak en during application of insulation blocks. Fiber Counts There are no established figures for a max imum allowable concentration of asbestos fibers in pipe covering operations or for short duration massive exposures. Because study in a textile mill in 1938 found no cases of asbestosis where. the count by impinger light field was below 5 mppcf, this figure became the recommended maximum allowable con centration.3 An asbestos operation in Canada has had no new cases of asbestosis in 15 years where the particle count is below 1 mppcf for dust below 10 microns.0 One TJ. S. in dustry uses 5 mppcf below 10 microns and 1 mppcf above 10 microns as their MAG.10 Pathologists find fibers exceeding 400 mi crons in lungs during autopsy,11 These long fibers do not settle in air as rapidly as spheri cal particles. They are less than one micron m thickness and their needle-like form allows them to stand on end and work down into the lungs. The Saranac Laboratory experiments by animal exposure to asbestos indicated that asbestosis is a mechanical rather than a chemical action.12 The researchers also con sidered fibers greater than 10 microns the most harmful. This is not in agreement with recent studies in South Africa where authori ties consider fibers less than 5 microns the rnost harmful.13 . . Dust counts, taken with the Bausch and Lomb Dust Counter, appear in Table I. The low counts on sampling do not appear to an adequate indication of the actual hazard. During sawing of blocks and pipe sections and removal of old insulation, the work environment appears extremely dusty. Respirator filters often clog after an hour's work removing insulation. Fibers from 3 to 60 microns in length re ceived special attention during this study (Figures 4 and 5). If fibers were present but count revealed less than one mppcf, they ap pear in Table I as a trace. X-Ray Findings It is common practice for industrial hy gienists to use information from periodic physicals to assure themselves that exposure controls are adequate. X-ray examinations on new employees in asbestos are not of value for this assurance; on the contrary,, this in formation can be extremely misleading as it usually takes a minimum of seven years ex posure for cases of asbestosis to develop.14'15,13 . It also appears that some people are suscepti ble while others escape harm during the same exposure.17 A medical team surveyed five shipyards in1945 to investigate the health hazard due to insulation work-18 Only three cases of as bestosis appeared in 1074 x-ray examinations. These three employees had worked in as bestos material for more than 20 years. In sulation material and work methods have re mained essentially the same since that study. The greatest change, starting right after the war. is the removal of insulation during over haul and repair. Many of our employees 26S May-Junc, 1%$. now have over 20 years in the insulation trade in contrast to the survey in 1945 ..where only 51 of the 3 074 employees had over 10 years experience in insulation work. Discussion The world's consumption of asbestos has increased from 500,000 tons in 1942 to 2, 400,000 tons in 1961.20 Recent studies recog nize asbestosis as a serious health haz ard.20'21'22 Asbestos exposure during- shipboard insula tion differs from exposure in mining and manufacturing processes of this material. In these industries employees usually continue at one job with the same material and their exposure is relatively constant. This is not true for shipboard insulation where the pipecoverers and insulators work location, work position, and material constantly change. Un der these conditions it is impossible to de termine the exposure of the employee without spending hours in observation and sampling. Samples taken as in Table I are only bases for discussion concerning their exposure. We do not know whether our cases of as bestosis came from massive exposure during removal of old insulation or from many years of exposure by susceptible individuals during all types of insulation work. Summary The Long Beach Naval Shipyard has sev eral men on disability compensation and one death due to asbestosis. .Many of these em ployees have more than 20 years' experience as pipecoverers and insulators working pri marily aboard ship. Asbestos exposure during ship overhaul and repair varies extensively giving an entirely different problem from exposure in mining and manufacturing operations. The maxi mum allowable concentration for pipe cov ering operations or for short duration mas sive. exposures is unknown. There still re mains a difference of opinion araoncr medi cal authorities on a MAC and the effects of long-fiber and short-fiber asbestos. Chest x-ray examinations of employees exposed to asbestos can be misleading as it usually takes a minimum of seven years for cases of. as bestosis to develop. Shipboard pipecovering and insulating during overhaul and repair is a hazardous trade. Employees in this trade should wear respirators when exposed to dry insulation material containing asbestos. References 1. Smith, Kenneth W.: Pulmonary Disability in a*. bestos Workers. AMA Arch. Ind. Health. I?- om (August 1955). '' 2. Maxcy, It. F.: Rosenau Preventive Medicine and Hr. giant. 7th Ed., p. 1052, Appleton-Ccnturv-Crofis Inc New York (1951). ' 3. .Lanza, A. j.: biticosis and Asbestosis, p. 58. Ox/ortl University Press, New York (1938). 4. Lanza, p. 59. 5. Hunter, Donald: The Disease of Occupations, p, 87B. The English Universities Press Limited, London (1355). 6. Bowles, Oliver: The Asbestos Industry, p, 2, V. S. Bureau of Mines, Bulletin 552 (3955), 7. Convention Proceedings: The Asbestos Worker. Vnl, 15, No. 1, p. 8, November 1962. 8. Lanza, p. 59. . 9. Personal Correspondence, Paul Cartier, M.D., Thetford Mines, Quebec. 10. Personal Correspondence. H. M. Jacicson, Medical Department. Johns-Manvilie Corporation, New York. 11. DaLLaValle, J. M.: The Industrial Environment and Its Control, p. 39, Pitman Publishing Corn., New York (1957). 12. "VOrwald, A. J., T. M. Durkan, and C. Pratt: Ex perimental Studies of Asbestosis, AMA Arch. Ind. Hyg. and Oec. Med. 3: 4 (Jan. 1951). 13. 'Personal Correspondence, C.G.D., Cowling, Pcnge As bestos Mines, South Africa. M. Lanza, p. 175. 15. Hunter, p. 079. 16. Johnstone, R. T.: Occupational Medicine and Indus trial Hygiene, p. 372, The C. V. Mosby Company, StLouis. Mo. (1940). 17. Lynch, K. N.t Pathology of Asbestosis, AMA Arch. Ind, Health. 2: 185 (-March 1955). 18. Fleischer, W. E-. F. J. Viles, R. L. Gade, and Philip Drinker: A Health Survey of Pipecaverin? Operations in Constructing Naval Vessels. /. Ind. Hyg and Tax. 28: 9 (January 1946). 19. Thomson, J. G.: Exposure to Asbestos Dust and Dif fuse Pleural Mesorheliomas. Brit. Med. J., p. 123 (January 12. 19G3). 20. Thomson, p. 123. 21. SmithER, W. J.: Mesotheliomas and Asbestos Dust, Brit. Med. ],. p. 494 (November .3, 1962). 01 McCaughey. W. T. E.: Exposure to Asbestos Dust and Diffuse Pleural Mesotheliomas, Brit. Med. p. 139' (November 24, 1962).