Document 3J6eoMy0442GMNOax4r9pdo7J

[47] Average Exposures Low /945 Results AvaiUiMe Table I lists the fiber exposure data obtained from over 200 dust counts by Fleischer in 1945 and also those ob tained by Murphy1 during 1965 and 1966. Using data supplied on the number of indisiduuls engaged in the various work activities, a timeweighted (actually man-weighted) av erage asbestos exposure is calculated. A detailed analysis of the results, however, presents difficulties. In each yard, a worker's average exposure was dominated by insulation activities aboard ship. For such activities, the average asbestos dust levels reported in Insulation Hygiene Progress Reports Vol. 6 No. 1 Spring t975 from the Insulation Industry Hygiene Research Program Editor: W. J. Nicholson, Ph.D., Pub lished at the Environmental Sciences Laboratory (Irving J. Selikoff, M.D., Direcior). Mount Sinai School of Medicine of the City University of New York, N.Y. 10029 Advisory Council of IIHRP Irving i. Selikoff, M.D. Program Director and Chairman E. Cuyler Hammond, Sc.D., Vice Presi dent, American Cancer Society, New York, N.Y. Andrew Haas, General President, Interna tional Association of Heat and Frost Insulators and Asbestos Workers, Washington. D.C. Fred L. Pundsack, Ph.D. Vice President, Research and Deselopment, JohnsManville Corporation, Denver, Colo. PURPOSES OF THE INSULATION INDUSTRY HYGIENE RESEARCH PROGRAM 1. To develop improved methods for minimizing exposure of insu lation workers to dusts and fumes encountered in their work. the different shipyards varied by nearly one hundred times. It should he recognized that these fiber counts represent all fibers enu merated in the field of view of a konimetcr. These would include fibers perhaps as short as 1.5 microns. Supplementary' data* on the size dis tribution of amositc aerosols in ship yards suggest that this overestimates the number of fibers longer than five microns by a factor of two. Taking this factor into account, the average of the eight-hour concentra tions of fibers longer than five microns in (he four U.S. shipyards studied by Fleischer in 1945 would be from 15 to 20 fibers per milliliter (f/ml). It must be emphasized, however. that such aver ages arc highly subjective and depend strongly upon the vagaries of the par ticular work practices selected for sam pling and conditions present at (hat time. Similar considerations would yield a value of 4 f/ml for the shipyard survey by Murphy in 1965-66. New Techniques Used The first research that quantified as bestos insulation exposures using membrane filter techniques was that of Bulzer and Cooper published in 1968* and extended in a report at the Dresden Conference on the Biological Effects of Asbestos in 1969.7 Their initial publication, however, enumerated fiber concentrations in marine and commercial insulation work in temts of all visible fibers, in cluding those shorter thjn five microns. The later subsequent publication also provided data on fiber concentrations longer than five microns. Table 2 summarizes these results. Using the information provided on dust concentrations and the percentage of time u worker is engaged in a larpractice, atune-weightedav -rageof 2.7 f/ml was obtained for oposurcs during asbestos insulation wort in light and heavy construction, and 6.' f/ml in marine construction and rcpaii. Cooper and Bulzer noted thit at the time ol their study, approximut :!y 55% of the work time of insulation workers was spent using materials ot ter than asbestos. Thus, cight-hotti timeweighted aserage exposures fi r asbes tos workers during 1968 in the western United States w ould have aver ged less than 1.5 f/ml in light and he vy con struction. Moreover, it is noeworthy that Cooper and Bulzer state tl cir sam ples were "deliberately taken under conditions where the highest i ust con centrations representative of; particu larjob u ere being developed. * Union Cooperation Obtained The environmental evaluat an of in sulation work that was undecaken by the Mount Sinai School of ledicine under the auspices of the lnsu ation In dustry Hygiene Research Pro ramsre vealed asbestos air conc ntrations somewhat higher than those ncasured by Balzer and Cooper. Again using in formation supplied by union members and from observation of w >rk prac tices. estimates were made o' the per centage of time workmen wer: engaged in various activities in comm xcial and industrial construction. The information on measu cd asbes tos air concentrations obtain :d during these work activities is show in Table 3. They were ut>ed as indicate 1 to arrive at the estimated time-weighu d average exposure of about 6 f/ml for insulators when working with asbestos Oniheascragc.inihceasti rn United TABLE 11 Asbestos fiber concentrations by membrane filler techniques Job Classification Prrcrataje* ot work with asbestos Unht and Mm) Industrial Hbcrvct AH Lengths Length > Sn Maria* Can^nxtJa and Repair nbMcc AH lengths Length > s* 2. To disseminate knowledge of these improved methods of dust control wherever they may be applied advantageously and to offer cooperation, advice and assistance toward their universal adoption. Prefabrication Application Mixing Finishing Tearing Out General TtnrtiAX/sii*hi.vl 10'S 40%. 5S 30* 10% 5% 10.1 12.4 2.4 2.7 12.8 0.8 .1 1 66 8.0 16 1.8 8.4 .5 *> 7 30.4 24.8 10.6 1.8 31.5 2 oo 20.0 16.8 7.1 1.2 20.2 0.1 AA 0049-0562 [49] V /r 1..^/^ /6//i/^ 0*49-0568 [SO] ''.Oh-n- c