Document k9xxDvKodJQqd9o8Bg6po98bB

FILE NAME: Asbestos Cement Pipe and Sheet (ACPS) DATE: DOC#: ACPS0 KhMENT DESCRIPTION::Z - Exposure of Insulation Workers to Asbestos Dust Work-Environment-Health, Vol. 8, n:o 1, 1971 Exposure of insulation workers to asbestos dust by Kaj Ahlman and Eero Siltanen* INTRODUCTION must nowadays submit to a periodical exami- Asbestosis was first described as an occupational disease among insulating workers by Ellman (5) in 1934. Since this initial report some hundred other cases of >>lagger's pneumoconiosis)) have been described, and this kind of occupation has been recognized as highly hazardous in industrialized countries all over the world. It has also been shown that there is a highly increased risk of lung cancer occurring in persons exposed to dusts containing asbestos in insulation work (7, 9). The first known case of pulmonary ashes;; tosis among insulation workers in Finland was 'I(. discovered as early as 1938 (1). The register of occupational diseases at the Institute of nation at least once every 3 years. It is obvious that sufficient attention has not yet been paid to the improvement of working conditions. Data on the situation in the varying kinds of insulating work are very scanty since neither systematic checks are made of dust concentrations nor is regular control of the use of personal protective masks performed. To obtain more knowledge on the environmental conditions of insulating work, the Institute of Occupational Health, in connection with an intensified investigation of asbestos hazards in general, recently started a program of measuring dust levels that includes insulating work places. Occupational Health in Helsinki now includes i a total of 56 cases of insulation workers with INSULATION WORKERS SUFFERING I pneumoconiosis. FROM ASBESTOSIS In order to obtain more information about I the prevalence of asbestosis among insulators, The number of cases of asbestosis diagnosed the Institute of Occupational Health carried among insulators before and including 1968 \ out a field investigation in 1962-1963 which have been given in table 1. They have been ' included all actively working laggers-in the arranged according to the year of diagnosis. three largest Finnish cities. This investigation was continued after an interval of a few years. The total number of workers examined during Table 1. The number of diagnosed cases of asbe<itosis among insulators in the years 1938--1968. the period 1962 through 1968 was 452, nearly 1938 three-fourths of all insulato.i;s still working in this country. In spite of these examinations, 1946 no reliable, current data regarding the true incidence of lagger's pneumoconiosis are 1952 available, and even less is known concerning 1953 the morbidity of former years. Work produc- 1957 ing the hazardous dust has been performed in 1958 .this country for several decades. According to 1959 1 case 2 cases 1 case 1 2 Case8 5 3 1960 1961 1962 1963 1964 1965 1966 1967 1968 5 cases 2 5 3 t 3 3 5 4 11 the newly revised law relating to the safety of Total 56 cases working environments, however, all workers Institute of Occupational Health, Helsinki, Finland. The duration of expo5ure to dust (working time as an insulator) was known in 46 cases 1 ,, and ranged from 10 to 40 years at the time of a~bestos. I\owadays, in addition to the old di.igno:;is. The distribution has been shown compound, mineral wool and glass wool, in table 2 according to the length of exposure, neither of "hich contains asbestos, are used using 5-year groups. for the same purpose. The work of a lagger is very dusty, particularly the repair and demoli- Table 2. Distribution of insulation workers with asbes- tion work that is done in cramped and poorly tosis according to the length of exposure. ventilated places. Protective masks were Exposure time in years Number of affected persons earlier rarely used, and their use is still often impossible because of cramped working :::;;10 0 11-15 4 16-20 9 21-25 9 26-30 13 >30 12 Unknown 9 spaces. Many different brands of asbestos materials are manufactured for the thermal insulation of pipes. The lining insulation materials used in pipe insulation work mainly consist of either diatomite and clay or vermiculite diato- Total 56 mite and clay, with only some per cent being amosite asbe,,tos. Bentonite and woodmeal are Ubed as the filler. Surface insulation material The main criterion for accepting a case as contain:; 20 to 35 % asbestos (antophyllite or asbestosis was the presence of typical radio- chrysotile and a slight amount of amosite) logical manifestations in the lungs, such as and Portland cement or clay. The asbestos interstitial or focal fibrosis, especially in the middle or lower areas. This was not regarded as sufficient for diagnosis, however, unless it insulation material most commonly used in Finland consists of 70 to 80 % diatomite, 10 to 15 % clay, 5 to 7 % asbestos (chrysotile was clearly proved that the patient had a and amosite), and some per cent vermiculite, sufficiently long duration of exposure. Pleural woodmeal and gypsum. calcifications or thickenings as the only In the shipbuilding industry sprayed asbes- noticeable radiological findings, without a tos insulation is used for ceilings and bulk- typical occupational history, were not enough heads. Even if the material is moistened it to classify the case as anything but suspected causes a lot of dust. Only some years ago the ' asbestosis. shipyards in Finland started to use non- \ The frequency of pleural calcifications or ~ombustible wallboard made of asbestos and radiologically visible pleural thickenings has calcium silicate. The insides of cabins and been shown in table 3. Some cases have been corridors, as well as walls and ceilings are lined with the board, a protective measure TableJ-:ftie frequency of radiologically visible pleural against fire that is demanded by insurance thickenings or calcifications in all cases diagnosed in 1960-1968. companies. The board is cut into the required sizes by circular or band saws, which produce Unilateral 9 Bilateral 18 None 14 Total 41 plenty of dust. These calcium silicate-asbestos boards contain about 30 % asbestos. excluded because of the uneven technical standard of earlier radiographs, and the group presented in the table consists only of the 41 cases diagnosed from 1960 through 1968. TYPE OF INSULATION WORK AND MATERIALS USED WHICH CONTAIN ASBESTOS The most common type of insulation work in Finland is the thermal insulation of pipes that is done manually, whereas asbestos spraying is rarely used in the building industry. Previously, insulating material was an asbestos compound consisting of clay, diatomite, and ASBESTOS DUST MEASURE..\1ENTS AND STANDARDS In recent years regular dust measurements have been made in the Finnish asbestos industry, but very rarely at places where insulation work is being done or where other asbestos products are being used. Methods Particle counting or gravimetric methods have been used for the dust measurements. The samples for counting asbestos dust particles were earlier taken with a midget impinger only (ethyl alcohol being the sampling medium). They were examined using a 2 I L ,' light field microscope with a magnification of 300 x. This year dust samples have also been collected on membrane filters and counted by phase contrast at a magnification of 500 x. All particle concentrations shown on this paper are still counted by the impinger lightfield count technique. The following four ways of counting asbestos dust are used: I) Counting all particles (fibers and grains smaller than 5 microns (<5 m) 2) Counting all grains larger than 5 microns 3) Counting only fibers as large as 5 to IO microns 4) Counting fibers longer than 10 microns All particles whose length is at least three times the width are considered fibers. For measuring the total ma:;s concentration of the dust, long-period sampies on membrane filters have been taken either from stationary points (Millipore Filter, Type AAWP 037) or from the breathing zone of the workers. Permissible dust concentrations According to American findings concerning asbestos dust particle concentration, a threshold limit of 175 particles per cubic centi- meter (= 5 mppcf) has been recommended as a ceiling value below which all concentlations should fluctuate (2), and a threshold limit of 70 particles per cubic centimeter (= 2 mppcf) has been recommended as a time- weighted average concentration as counted by the impinger light-field count technique _)3). The same values have also been recom-- mended in Finland. In the U.S.A. there has also been a tendency to recommend a thres- hold limit of 12 fibers per milliliter for fibers longer than 5 microns, as determined. by the membrane filter method, at least at a phase contrast magnification of 430 x (2). Assuming there to be a I %risk of contract- ing asbestosis during a 50-year working exposure, the Committee on Hygiene Stan- dards of the British Occupational Hygiene Society has recommended the following criteria for limiting exposure to chrysotile asbestos (4): Dust category Negligible Low Medium High Chrysotile concentration* Fibers/ml** <0.5 0.5-2 2-10 >10 Average during a 3,rnonth period Greater than 5 m in length From these criteria a limit of 100 fibers per milliliter-years was proposed, hence a limit of 2 fibers per milliliter averaged over a 50year period. The same values should also he recommended for all other forms of asbestos, with the exception of crocidolite (8). We have not yet established any recommendations for asbestos dust mass concentrations in Finland, but, according to simultaneous, comparable dust measurement& in the plants manufacturing asbestos products, the mass concentration of asbestos dust equivalent to 70 particles per cubic centimeter would be of the order of from 0.7 to 1.0 mg/m3, and the corresponding equivalent to 175 particles per cubic centimeter would be from about 1.75 to 2.5 mg/ml. In the Soviet Union the thresholtl limit value for dust containing more than 10 % asbestos is 2 mg/m3, and the same value is used in Czechoslovakia. Recently it has been reported (4) that in the Federal Republic of Germany the following values are used as a temporary measure for the assessment of asbestos dust mass concentrations: 2 mg/m3, if the asbestos content of processed raw material is below IO % 1.5 mg/m3, if the asbestos content 1s between IO and 50 % LO mg/m3, if the asbestos content 1s higher than 50 % _RESULTS OF DUST MEASUREMENTS The dust concentrations measured in the air of the breathing zone of workers during the manufacturing of insulation materials has been given in table 4. The table shows that_ the measured dust concentrations exceed the recommendations many times, and, therefore, the use of protective masks has been recommended for the workers until it is possible to employ a more effective method of dust control. Even if only 5.2 % to 8.9 % of all the dust particles in the air are asbestos fibers, the concentration is still very high. Dust concentrations measured during the insulation of ordinary pipe with asbestos insulation material in the building industry have been shown in table 5. The measured concentrations in this work were approximately equal to those in the manufacturing of insulation material and are thus very high. The insulation workers, with the exception of one, did not use protective masks because t~ey thought it impossible in the cramped working 3, . 4 Table 4. Asbe.stOli dust concentrations measured during the manufacturing of inaulation material. Survey No. Operation -- l Loading of elevator (l'>ith bags) Filling of drum mixer Bagging machines 2 Loading of elevator Bagging machine 3 Loading of elevator Bagging machine Particles per cubic centimeter Particles <5m Grains >5 Jim Fibers >5m 439 67 18 652 63 40 751 61 44 1,270 175 122 250 36 24 856 128 76 478 146 6 616 139 77 Fibers >lOm 10 16 24 19 6 16 5 29 Total 534 771 880 1,586 316 1,076 635 861 Table 5. Aabestm; du;;t coiH.:entrations in irn,ulation work in the buildmg in<lu6try. III Operation Measured dust concentrations Particles per cubic centimeter - Particles <5 11m Grains >5 m Fibers >5 m Fibers >l0m Total Mass con centration mg/rn l\lixing of the insulation material . 660 195 53 3 911 I Insulation of pipe, breathing zone 1,380 280 60 26 1,746 20.0 Insulation of pipe, general air 1,090 265 92 14 1,461 Insulation of pipe, breathing zone 840 160 61 11 1,072 20.0 I Insulation of pipe, general air 710 134 34 12 990 r Table 6. Asbestos dust concentrations measured during the sawing of asbestos-calcium 6ilicate boards in a shipyard (Navilite boards). / Measured dust concentrations Particles per cubic centimeter Place of measurement Particles <5m Grains >5m Fibers >5m Fibers >l0m Total Mass concentrations mg/m ---- l Board feeder's breathing zone 1,317 141 86 45 1,589 17.1 ReceiYer of sawn boards, breathing zone 2,740 308 148 190 3,386 2,950 131 220 100 3,401 20.3 1,995 197 163 154 2,509 General air, 10 m from saw 1,046 82 51 20 1,199 spaces. Thus they were obviously exposed to very dangerous asbestos concentrations. Personal, long-period, gravimetric dust samples were also taken from the breathing zone of one worker. Membrane filter monitors were connected to a personal sampler pump worn by a worker who had the filter monitor attached to his collar. The measured mass concentrations were very high. In the shipbuilding industry asbestos dust measurements have been made only once. The results of these measurements have been given in table 6. Also in this work dust samples were taken with portable personal sampler pumps, the membrane filter being attached near the breathing zone. All measured dust concentrations were very high and indicated an obvious risk of asbestosis. Due to the dust measurements the shipyard has undertaken more effective dust protection 4, I L I l), < ' j I I r l measures. A remeasurement of dust levels will determine to what degree these preventive measures have succeeded. CONCLUSIONS The numerous incidents in recent years of verified asbestosis among insulation workers in the construction and shipbuilding industries indicate that previously there was little knowledge about the health risks connected with this work or that such knowledge was simply ignored. The dust measurements of the last few years also clearly indicate that obviously a large number of workers are still exposed to d,mgerous a,;bestos dust concentrations. Thus it is extremely important to examine, on a larger scale than previously, the working conditions of workers using asbestos materials in the building industry and in shipyards and to improve the medical and technical protection of such workers against the risk of asbestosis occurring. REFERENCES 1. Ahlman, K. Asbestosis among insulation workers in Finland. International congres11 on occupational health proceedings, Vienna, (p. 19--24) 1966. 2. American conference of governmental industrial hygienists (St. Louis, Mo.). Threshold limit values of airborne contaminants for 1968. ('.\lay 13) 1968. 3. American conference of governmental industrial hygienists (St. Louis, Mo.). Supplemental documentation of threshold limit value.i, asbestos all forms. Transactions of the thirtieth annual meeting of the American conference of governmental industrial hygienists (p. 188-191) 1968. 4. Committee on hygiene standards of the British occupational hygiene society. Hygiene standards for chrysotile asbestos dust. Ann. occup. hyg. 11:47-69, 1968. 5. Ellman, P. Pneumoconiosis: Part III. Pulmonary atibest0ois. Brit. j. r-a<liol. 7 :281. 1934. 6. Hasendever, D. and Schi.i.t.z, A .\lea:.urement of du;;t containing asksto,; fur a,.;e.,,.,iag asbe;,to11 hazards. International conforence of pneumoconiosia, Johan nesburg, April 23-May 2, (p. 301-303) 1969. 7. Hinson, K. F. W. Cancer oflungs and other diseases after exposure to asbe..tos dust. Brit. j. dis. chest 59:121, 1965. 8. Holmes, S. Personal communication, 1969. 9. Selikoff, I.]., Churg, ]. and Hammond, E. C. Asbestos exposure and neopla6ia. J.a.m.a. 188:22, 1964. J 5 I I . ._