Document EvmoKnVX9y6mKkBRYbMJgpVrN

PPG--INuDUUCSUTRMIEENS,TINWCA. SDINDONTOAT CROEMCEORFDROOMF IT'S FILES. AND C.ANNOT"BE AUTHENTICATED BY PEG-INDUSTRIES, INC. * n. * :* *.. * tr* Asbestos vjj Po**rt*io**n* Findings ot mesothelioma among individuals living in the vicinity of asbestos plants suggested that asbestos air pollution might occur. Measure ment ot asbestos (chrysotile) content of ambient air in New York City and other locations showed levels ot 10 to 50 x 10- gm/cu m, and lungs of New York residents examined at autopsy regu larly showed chrysotile fibrils. Occurrence of asbestos air pollution Is now established. What have not yet been defined, however, are the dimensions of disease hazard which may be associated. Epidemiological considerations sug gest that it is improper to equate the several kinds of asbestos exposure: direct occupational, indirect occupational, exposure in family cir cumstances, neighborhood contamination, and general community asbestos air pollution. Since most uiban air pollution is derived from com mercial and industrial sources, the asbestos in dustry has both important responsibility and opportunity for its control. E.lARLY in the 1960s, the problem of as bestos disease was disseminated from the occupational area into the general, environ ment. Three germinal observations were re sponsible for this. First, Kiviluoto reported finding 499 cases of parietal pleural calcification among 6,312 residents of a rural county in Finland.1 This came very much as a surprise, since the type of calcification observed had previously been Submitted for publication Feb 9, 1971; accepted Feb 17,1972. From Mount Sinai School of Medicine of the City University of New York, New York. Hoad before the American Medical Association Research Conference on Air Pollution, New Orleans, Oct 6,1970. Reprint requests to Director, Environmental Sci ences Laboratory, Mount Sinai School of Medicine, Fifth Avenue and 100th Street, New York 10029 (Dr. Selikoff). described primarily in asbestos workers,2 usually more than 20 or 30 years after start ing work3; yet the cases were not among asbestos workers, but among farmers and farmers' wives. The asbestos link, however, was there; the county did have an asbestos mine. The natural supposition was that as bestos air pollution from the mine was re sponsible, a presumption that was strength ened when the specific type of asbestos pro duced by the mine (anthophyllite) was found in the air up to 50 km away,* and asbestos bodies were demonstrated in the lungs of cattle grazing in the nearby fields.1 The same year (I960) saw a second wor risome communication. Wagner et al5 re ported 47 cases of pleural mesothelioma in a part of South Africa which was important for asbestos mining. They noted potential asbestos contact for most of the patients two or more decades before, in many instances merely the result of living in the general area or of chance contact in a family setting. While pleural mesothelioma had previously been attributed to asbestos exposure, the strength of this association had not been appreciated. More pertinent was the demon stration that it could result from other than occupational exposure. Amplification soon followed. Newhouse and Thompson7 studied all mesotheliomas at the London Hospital. They confirmed the close association with asbestos, 31 of the 76 subjects having had occupational exposure. They also confirmed the impor tance of nonoccupational contact; of the 45 who had not worked with the material, nine had lived in the households of asbestos workers and 11 had lived, decades before, within one-half mile of an asbestos plant. 1 Arch Environ Health-vo,AtyoffE. THIS DOCUMENT D10'> - NOT COME FROM PPGLFIliE 00 T ' tuj: ` .1 1 BB 0005477" ASBESTOS AIR POLLUTION--SELIKOFF ET AL I i wir m WWaiWWW iWawwril tiMiiii emtWHWgffgfflW!WtT 5 f^ ^ Lieben and Pistawka reported similar find and we would not expect their risk to be ^ ings in Pennsylvania.8 duplicated in the general population. But is V What appeared to be a strong link in the part of their risk disseminated, with the chain of evidence for environmental asbestos dusts from their work? What sort of dose-re- - disease was the report in 1963 by Thomson sponse curve are we dealing with? Is there a > et al that asbestos bodies were commonly to threshold which, once crossed, leads to seri- - be found in the lungs of the general popula ous hazard of neoplasia? An hypothesis - tion of Capetown, South Africa. They ex could be formulated that such a threshold pressed a drop of lung tissue fluid onto a calls for very little asbestos (since small slide, examined it by optical microscopy, amounts may still reflect billions of fibers or' and in one quarter of 500 consecutive autop fibrils, or both), and that asbestos workersi sies, found structures apparently identical pass it early in their careers. with those seen in asbestos workers' lungs. Such an hypothesis, or some variation of But these were not asbestos workers; they it, is not inconsistent with observations 4t had been ordinary citizens of this large city. made in the last several years. Neoplasms,-3 Thomson and associates concluded that the such as pleural and peritoneal mesotheli- %, subjects had inhaled asbestos in the course oma, occur in excess even among asbestos J of their urban living, from the many asbes workers with little or no radiological evi--i tos products about them. With knowledge of dence of asbestosis, suggesting that expo- ^ what exposure to these fibers could do under sures insufficient to cause asbestosis may industrial circumstances as a background, still produce neoplasia. The spread of this-rt and with the observations of Wagner et al5 separation is not established, but it is appar--* as an example, they suggested that we were ent recently that while lower dust levels in 4S now faced with a "modem urban hazard" industry may prevent much asbestosis, such 4 and predicted that asbestos-associated neo levels will not necessarily prevent cancer.11 5 plasms would rival cigarette-induced lung It is not now known how low a threshold -* cancer in the future. must be to prevent asbestos-associated neo- 4 It should be noted that the prediction of plasms. Thomson and associates8 is an extrapola tion. It is a wide step from occupational Asbestos in Lungs exposure, with large numbers of asbestos bodies, to community contamination, with, as a rule, far fewer bodies, particularly with It thus became important to know whether little knowledge of a dose-disease response asbestos truly was a common contaminant i relationship. Also, the particles described of urban dwellers' lungs. The demonstration 4 had the appearance of those seen in asbestos that "asbestos bodies'* were to be regularly ^ workers, but some uncertainty existed that found at autopsy in many cities of the * these necessarily had an asbestos core,10 es world10 confirmed the finding of Thomson et * pecially since it had been known for 30 al,8 but did not settle the question. It was * years that such bodies could be found after not known whether the cores were necessari- $ exposure to other fibers as well.11 ly asbestos, an uncertainty resulting from * Despite these caveats, the three reports, technical difficulties involved in analyzing i taken together, posed a problem that is now such cores.17 J very real. Occupational asbestos exposure In recent months, the impasse has been may be associated with serious risk; for resolved by direct search for asbestos fibers example, among asbestos insulation workers and fibrils.18 Investigation of 3,000 consecu in the New York metropolitan area at this tive autopsies in New York had shown that time, approximately one in five deaths is "asbestos bodies" were common; optical mi due to lung cancer, one in ten is due to croscopic examination of 175/i X 1 sq cm of mesothelioma, one in ten to gastrointestinal lung tissue in each of these cases, showed cancer, and one in ten to asbestosis and cor asbestos bodies in 1,449 (48.3%) (Table 1). pulmonale.1214 These men have been ex It is likely that, had a greater volume of posed to amounts of asbestos surely greater tissue been submitted for study, asbestos than those in the surrounding community, bodies would have been found in all the en GO LU CD - `% Ag* <1 1-19 20-39 40-59 60-79 80+ Total From Age <1 1-19 J 20-39 40-59 60-79 80+ Tote Sex Male Femal Toti * From cases, except per young children. The same exa. addition to cce bodies"), uncoatc also readily seen than 1.0,1 were found; most of th tified, although ments, glass fiber more concerned, bers, less than 1would be more the asbestos vari asbestos used hi thin fibers were ing found in l.C tending to vary number of asbu The critical k examining, in -- small portion mated nt- 1~* Arch Environ Health--Vol 25, July 1972 Cj | BD 0005473 1 w--*-.-- ASBESTOS AIR POLLUTION--SELIKOFF ET AL eir risk to i,. - But th iiv. Di dosore. *th? Is then- n leads to m ritn hypothec,. i a threshold (since sm.ili >ns of fiber> or >estos wort t r- e variation of observation- s. Neoplasmal mesothdinong asbesto liological t \ j. ig that e\|xi bestosis m:n pread of thi nt it is app.irdust levels in bestosis, such vent cancer,' v a threshold sociated nco Table 1.--Asbestos Bodies in 3,000 Consecutive Autopsies in New York City, 1966 to 1968* Mai* Female Total Agm No. <i 1-19 2/73 0/7 20-39 40-59 34/102 316/606 60-79 555/997 8Q+ 106/186 Total 1,013/1,971 From Langer et al.'* % 2.8 0.0 33.3 52.1 55.7 57.7 51.4 No. 2/53 4/25 19/58 108/247 220/491 83/155 436/1,029 % 3.8 16.0 32.8 43.7 44,8 53.5 42.4 No. 4/126 4/32 53/160 424/853 775/1.488 189/341 1,449/3,000 % 3.2 12.5 33.1 49.7 52.1 55.4 48.3 Table 2.--Numbers of Asbestos Bodies* Atbtitai Bodies 0 Ago <1 1-19 20-39 40-59 60-79 80+ 122 28 107 429 713 152 Total 1.551 Sex Male Female 958 (48.6%) 593 (57.6%) Total 1.551 * From Langer et al.' 1-4 2 4 53 359 630 156 1.204 802 (40.7%) 392 (38.1%) 1,194 5-14 2 0 0 45 105 40 192 152 (7.7%) 40 (3.9%) 192 15+ 0 0 0 20 40 3 63 59 (3.0%) 4 (0.4%) 63 Total 126 32 160 853 1.488 341 3,000 1.971 (100.0%) 1,029 (100.0%) 3.000 mow whether contaminant emonstratioi; be regulnrh cities of iht ' Thomson et stion. It w.ire necess-irisulting from in analyziiur se has been -bestoS fibers D00 consem1 shown that i; optical mi < 1 sq cm o' ises, sho\u'<i ) (Table 1 r volume of dy, asbes'.r 1 in all ihe , except perhaps the infants and very SJrong children. j^The same examination showed that, in -.addition to coated particles ("asbestos bodies"), uncoated inorganic fibers were 7bo readily seen (Table 2). Fibers thicker 8nn, 1.0/* were almost universally to be ffcxmd; most of these are as yet still unidenfified, although some were diatom frag ments, glass fibers, or phytoliths. We were d*** concerned, however, with thinner fi- Jess than 1.0/* in diameter, since these ^iroald be more consistent with chrysotile, asbestos variety making up 95% of the ^tos used in the United States. Such ftiin fibers were also commonly present, be- og found in 1,038 of the 3,000 cases, and Coding to vary proportionately with the ttimber of asbestos bodies (Table 3). -Ihe critical information was obtained by ttanNJung, in 28 of the 3,000 cases, a very naU portion of lung (conservatively esti^ld at 1(H) by a technique which allowed qualitative analysis,17 with ap preciation that the unique structure of chrysotile allows its specific identification by high magnification electron microscopy. Chrysotile fibers or fibrils, or both, were found in every specimen (Fig 1). In four of the 28, background contamination could conceivably have been responsible for the findings. In 24 of the 28, the number found was greater than background counts could explain (Table 4). The morphological ap pearance and other characteristics of these fibers and fibrils are recorded elsewhere.19 It is evident that chrysotile asbestos is a common contaminant of the lungs of New York City residents at this time. Similar electron microscopic observations have been recorded in London,20 where not only was chrysotile asbestos found in almost 80% of cases, but it was noted to be the most com mon and most abundant of all fibers detected. The question inherent in the observations of Thomson and associates* in 1963, is Arch Environ Health--Vol 25, July 1972 n: BB 0005479 uu.ijijpuu epmi 4 ASBESTOS AIR POLLUTION--SELIKOFF ET AL Table 3.--Correlation of Inorganic Fibers with Asbestos Bodies in Lungs of 3,000 Consecutive Autopsies in New York City, 1966 to 1968* Percentage of cases showing asbestos bodies in relation to occurrence of thin Inorganic fibers Thin Inorganic Fiber* Asbestos Bodies 0 0 No. 1.168 % 59.5 1-4 No. % 332 38.3 5-14 No. % 35 28.0 1-4 705 35.9 424 49.0 52 41.6 5-14 76 3.8 89 10.3 21 16.8 15+ 13 0.66 20 2.3 17 13.6 Total 1.962 65.4 865 28.8 125 4.1 Percentage of cases showing thin inorganic fibers in relation to occurrence of asbestos bodies Asbestos Bodies 15+ No. % 16 33.3 13 27.1 6 12.5 13 27.1 48 1.6 Thin O 1-4 5-14 15+ Ft bart No. % No. % No* % No. 0 1,168 75.3 705 59.0 76 39.6 13 1-4 332 21.4 424 35.5 89 46.3 20 5-14 35 2.3 52 4.3 21 10.9 17 15+ 16 1.0 13 1.1 6 3.1 13 Total 1,551 51.7 1.194 39.8 192 6.4 63 * Correlation was done by optical microscopic study, from Longer et ai. * % 20.6 31.7 27.0 20.6 2.1 Table 4.--C hrysotile in 28 Casas Studied by Electron Microscopy Group 1 2 3 4 5 "Blank grids' No. of Chrysotile Fibers + Fibrils 9 10-50 51-99 100-200 201 S9 Cases 4/28 11/28 6/28 4/28 3/28 4*. Male 3 5 i 4 3 ... Female 1 6 5 0 0 chrysotile asbestos commonly found in the lungs of urban dwellers at this tune?" has now been answered, "Yes, unequivocally." Relation of Asbestos Lung Burden to Environmental Asbestos Disease There are few data at this time that would allow judgement of the significance of the asbestos we have found in lung tissue of urban residents. "Whether or not the amounts present as the result of other than occupational exposure are associated with frequent risk of disease is not known. In part, this is a reflection of the scarcity of data concerning the asbestos content of lungs in general, including those of asbestos workers. Such data as are available suggest that the amount in lungs of the latter is quite small, ranging from 0.6% to 0.001% of lung weight.2123 It would be expected ta even lower in those not occupationally posed. No information is at hand concerning asbestos content of the lungs among cases of Wagner et al,B or Newhouse Thompson,7 or those of other cases wi environmental disease.23124 Nor is quantitative information concerning the bestos content of the lung in individuals the general population without stigmata asbestos. This is rather urgently nc with age, sex, residence, and occupa' exposure taken into account Studies now in progress in our labors and elsewhere (F. D. Pooley, PhD, communication [July 1970]) indicate suitable quantitative techniques for ing asbestos lung content will be f and that fairly accurate estimates, app Arch Environ Health--Vol 25, July 1972 s Bodies 966 to 1968* L_ 15+ No. % ie 33.3 13 27.1 6 12.5 13 27.1 48 1.6 15+ No. % 13 20.6 20 31.7 17 27.0 13 20.6 63 2.1 ould be expected not occupationally t hand concerning he lungs among l,5 or Newhouse : of other cases wr ja.M Nor jg tk' m concerning the ung in individuals without stigmata ier urgently needecfc ce, and occupation^ count ress in our laboratoh . Pooley, PhD, ok 1970]) indicate th* chniques for estimat' tent will he feasibk e estimates, appron ASBESTOS AIR POLLUTION--SELIKOFF ET AL mating an order of magnitude, are to be pleural calcification in some rural areas anticipated in the future. Czechoslovakia.28-2* At first, it seems somewhat surprising Asbestos Air Pollution so few data are available concerning asbestos content of ambient air, It is probably an entirely justified concept since so much is known regarding the that the asbestos found in urban dwellers' tos content of air within the work place. lungs is derived from the inhalation of air Perhaps the best explanation is that oi contaminated with these fibers. Very little is the factory gates are passed, a whole new set! known, however, of the conditions of such of technical problems is encountered, contamination, and facile assumptions sampling procedures, analytical approai should be avoided at this time. and measuring methods useful for indusi An example of where an "obvious" expla controls are no longer applicable. nation might also be inaccurate may be Fiber Identification.--Under the mi found in the assumptions adopted to explain trial circumstances, there is usually no pi Kiviluoto's1 observations. It seemed natural lem to knowing exactly what is being to expect that the demonstrable anthophyl- sured, since the materials being used lite asbestos air pollution from the mine and either well characterized or can be readil: mill was etiologically related to the equally analyzed. Thus, whatever fibers are seen demonstrable asbestotic pleural calcification . be confidently labelled as "chrysotile," " in the population living about that point cidolite," "amoeite," "fibrous glass, source. It turns out, however, that this may other types. not be the entire explanation, and that inti If these same fiber's were to be seen in mate contact with local asbestos-bearing random sample, especially if they are rocks, including those used in building our confidence disappears. All that can houses, saunas, bams, and the like, might said is that inorganic fibers are present also play a role.25 Even then, if these fibers were found in Indeed, the latter association better ex large numbers, identification could be reai plains almost identical epidemiological find ly accomplished by such mass techniques ings in Bulgaria, where, again, pleural calci x-ray diffraction. When they occur singly oj o r-j* fication was found in a rural population. In randomly scattered in small numbers, "----- this district, too, an asbestos mine was being techniques are no longer applicable; worked, but it was an underground mine readily available alternate approaches, : i.-j and had opened only in 1943, too recently as polarized light microscopy, hardly ha' for its discharges to be expected confidently the same definitive assurance. While it to have had the effect noted25 (the lapsed true that analytical attack on single fibers period between initial exposure and evi still possible, these approaches (incl dence of pleural calcification is 20, 30, 40, or electron microprobe analyses, electron m re years). As in Finland, the local field fraction, and electron microscopy) are rocks have a high asbestos content and are consuming and often restricted by the used for various structures by the farming of the particle available for analyses. population, which then may have intimate Particles and Fibers.--There has loaf- contact with what is shed from them. More been an anomaly in particle counting for important, perhaps, the soils tilled by these asbestos threshold levels. In the United fanners can be demonstrated to have asbes States, a threshold level was proposed m tos fiber (anthophyllite) content. The im 1938 for occupational exposure to _ portance of this observation was empha based upon experiences necessarily limit sized by the discovery that those farmers to that point.30 The recommendation refledf working plots without asbestos soil contami ed the instrumental restrictions of the time* nation had little pleural calcification, where and were based upon counting of "particle^! as farmers working soil with anthophyllite by optical microscopy. It was recognu readily showed the radiological changes.27 It that such particles could either be fibrous * may be that similar explanations will be nonfibrous and that the proportion couH come available for the finding of endemic vary widely according to the materials | BB 0005492 | Arch Environ Health--Vol 25, July 1972 r AL in Gome rural areas # om^^t surprising that vailmre concerning tK ambient air, especial! iwn regarding the asb&. within the work plan xplanation is that onc> passed, a whole new & ms is encountered, an5, analytical approach^ lods useful for industit r applicable, ion.--Under the indit there is usually n pro!ctly what is being mes aterials being used ar rized or can be readi! fever fibers are seen caed as "chrysotile," "cit. " "fibrous glass," an rs were to be seen in \ ecially if they are smal ppears. All that can h mic fibers are prefer, ibers were found in ver tification could be readJ such mass techniques t her occur singly in numbers, the' longCT applicable; ar. emate approaches, sue nicroscopy, hardly ha* assurance. While it: attack on single fibers approaches (includi? analyses, electron i n microscopy) are 1 Vm n restricted by the sr ible for analyses. j hers.--There has Iff t particle counting I* levels. In the Univ level was proposed: al exposure to asbesv nces necessarily limit' recommendation reflff restrictions of the tin* i counting of "particlr >py. It was recognu ould either be fibrou? t the proportion co ig to the materials w. V* Pifl 2.--Clay particle with adsorbed chrysotile florila, in air sample about construction site (x28,000). Arch Environ Health--Vol 25, July 1972 i Ai i CO ;.u 'J -. j rr' | < c11 n jJ I i; Fig 4.---Single, she downwind of chrysoti non of clsy particlo. process studied, or other factors. Since the presumption is that only the fibers are re sponsible for the biological effect, such ana lytical dilution is hardly acceptable at this time, and current approaches to industrial threshold limit values are based entirely on fiber count But even here, the matter is not so easily disposed of, since the admixture of particles and fibers often includes surface interactions among them. Figures 2 and 3 show particles of clay and a diatom collect ed near a construction site by one of us (A.M.L.). By light microscopy these would be categorized as "particles." Yet, by elec tron microscopy, it was found that numer ous fibers (fibrils) were attached to the sur face of the particles (opposite surface charges). In such circumstances, any biolog ical effect of the fibers could be incorrectly attributed to particles. The question of size and magnification is critical. Fiber-Fibril.--Each asbestos fiber variety is quite different chemically, physical structurally, and morphologically.** Ct tile seems unique in its tendency to physical instability under a number of circumstance^ The chiysotile "fiber" is not a unit whotf|l but is, rather, composed of a large number 1] of individual fibrils, each from 300 to 40& || Angstroms. Under industrial circumstanaJf it is recognized that when a population of fibers is counted, "invisible" fibrils are also present,82 but that the optically visible fibos reflect, in varying proportions under differ ent circumstances, the total chiysotile popu lation, even though there is only one fib* for a very large number of fibrils. Also, with proximity to the industrial source, izaBj fibers are still present, not having been sub jected to influences which could result & their separation into fibrils. & In the ambient air, however, very little 4 known about the proportion of fibers .4 fibrils. The matter is of some important Arch Environ Health---Vol 25, July 1972 since not only mi as fiber and fibril, potential biologic different with th mass, with differe The proportion of determined withou Size.--Thus, a c asbestos air pollu techniques which particles. It is u: 'Fhich do not inc -eor>e will be effe idd that high magi ropy will be neec tions of at least 20 :,bly over 40,000 > ropy may be si occupational asbest mountable inadequPollution of the ami In addition to t fibrils, it has been < "f them are quite 00 ]* uLi' ! J^BB~0005434~1 l ' ica'^^physk i! k. gic^J.31 Chrwi idency to phy.-n-nl of circumstance not a unit whulc >f a large numix-r from 300 to ial circumstan'i->, 1 a population ot e" fibrils are :i1m> cally visible fiN-rs ons under ditTer* 1 chrysotile popuis only one t'.Ur fibrils. Also, with al source, many having been ?nht could result in ver, very little i? ion of fibers to me importance. ASBESTOS AIR POLLUTION--SEUKOFF ET AL 9 - .Hki: 4.--Single, short fibrils collected 3/16 of mile wind of chrysotile source. Arrow Indicates posii of clay particle. ice not only must number be categorized fiber and fibril, but the surface area and mtial biological effect might be quite erent with the same total chrysotile with different percentage fibrillation, proportion of fibers to fibrils cannot be without the electron microscope. Size.--Thus, a critical factor in studying air pollution is the utilization of jques which will measure very small les. It is unlikely that approaches do not include the electron micro'Pe will be effective. Indeed, one might that high magnification electron micros will be needed, including magnificaof at least 20,000x (direct), and probover 40,000 x. While optical micros- ^7-rj may be suitable as a guide for ^occupational asbestos exposure, it has insur.` vmountable inadequacies in studying asbestos ^pollution of the ambient air. addition to the fine diameter of the "fibrils, it has been our experience that many them are quite short, as well. We have observed chrysotile fibrils with lengths less than 1,000 A in many instances; when these are enmeshed in sampling debris, not only is high magnification election microscopy nec essary, but visual scanning may be inade quate, and inferior to photographic re cording,17 It may be worth noting that such small particles are at present subject to identifica tion by their morphological characteristics only; structural and microchemical analysis by electron microprobe or electron diffrac tion study has many difficulties. It may be hoped that instrumental advances will reme dy this situation (greatly improved micro probe definition can be anticipated, for ex ample). Turkevich's "World of Fine Parti cles"*3 is surely with us. Quantitation.--Under industrial circum stances, there is little difficulty in estimating the quantity of asbestos in a given sample of air. From this, the surface area of the fibers can be estimated or directly measured by nitrogen absorption or other techniques. It is even possible to conceive of gravimetric methods, rather than the more laborious counting of fibers. Quantitation is much more difficult in ambient air samples and, in our experience, only approximations can presently be obtained. Current Approaches to Asbestos Air Sam pling.--With the foregoing factors in mind, the absence of published information on as bestos levels in urban ambient air may be understood. Few air monitoring agencies have had available the technical equipment for the examination of ultramicroscopic as bestos fibrils. Moreover, even those fibers seen by optical microscopy in air samples required elaborate techniques (such as elec tron diffraction or microprobe analysis) for positive identification. Present approaches to quantitating asbes tos levels in ambient air, using ultramicro scopic techniques, have sought two objectives. The first is to obtain a measure of the mass of asbestos per unit of air volume at various locations in urban centers and later, for comparative purposes, in more rural areas. This would provide a stable estimate, since fiber size distributions change as sampling is undertaken at different distances from as bestos emission sources. Equal numbers of fibers can represent significantly different O co E5 UlI UJ CD Qn /?> O fa -.a: o i3 ' J Arch Environ Health--Vol 25, July 1972 i i1t I i _ "j bb 0005495^ 10 ASBESTOS AIR POLLUTION--SELIKOFF ET AL amounts, by weight, of asbestos. Moreover, it is not currently known how strongly bio logical effect is dependent on fiber size. This being so, a measure by mas or weight may be more conservative for the establishment of air quality criteria and standards, since the biological effect of a sample dominated by large fibers may be overestimated. Secondly, fiber size distribution is impor tant At the moment, to obtain such a distri bution at each sampled site is time-consum ing, and the presence of other material and tained by measuring the volume of as! per grid square and multiplying by the i propriate density. Figure 4 shows isolated fibrils in an ambient air sample i seen by electron microscopy. Usually, single fibrils, if any, are observed in microscopic field. However, as one takes samples sources of asbestos, more large fiber are present in the initial sample. As are dispersed during sample preparation^ casionally some groups of fibrils remain practice to spray fi Dining from 10% girders, spandrels, ,,tli,c buildings. Of ticr.s were taken b> -pray material a ,,f : i -bestos-containii r widespread arc prictiee was of sue w York City has x- (. ,-tos fireproofing, existing transfer and sampling methods may distort the observed fiber distribution. How ever, experiences in current studies suggest that these problems can be overcome, and that complete fiber size distributions will be obtained at selected sites in the near future. Sample Preparation.--In our studies, air samples were collected on membrane filters having an effective pore size of either 0.8/j. or 1.2n. While this pore size is larger than the largest dimension of some asbestos fi brils, it has been found that" the surface charge properties of the filter and the asbes tos, as well as the circuitous path through the filter, allow virtually complete collection of all asbestos material. Both high-volume samplers capable of drawing 40 cu ft/min through an 8 X 10inch filter, and small battery-operated per sonnel monitoring samplers with a capacity of 2 liters/min through 8 sq cm, were found effective in sample collection. Portions of each collected sample were ashed in an acti vated oxygen asher which oxidized the mem brane filter and all organic or carbonaceous material in the sample.3* The residue, con sisting mostly of fly ash and mineral matter, was dispersed on a microscope slide by grinding in a solution of 1% nitrocellulose in amyl acetate for two to five minutes. Upon evaporation of the amyl acetate, the dispersal was scanned for uniformity by op tical microscopy and a representative area chosen for transfer to an electron micro scope grid for scanning. tact The presence of these bundles, or e\ localized fibril clumps, gives rise to a tion between samples greater than would expect from statistical considerat alone. However, the scanning of many squares serves to average their effect Results of Initial Investigations.--I bient air levels were measured at sites in New York City. These samples taken at selected locations of the sampli network of New York City's Department! Air Resources. The sites were all located i public buildings distant from any significant source of asbestos. The chrysot content of ambientair in the various pling locations was as follows: Manhat 25 to 60, asbestos air level in 10* gm/cu: Bronx, 25 to 28, asbestos air level in 1C gm/cu m; Brooklyn, 19 to 22, asbestos level in 10- gm/cu m; Queens, 18 to asbestos air level in 10* gm/cu m; Staten Island, 11 to 21, asbestos air in 10* gm/cu m. "While preliminary*j nature, the samples from Manhattan to be higher than those from other bor Lowest values were usually from sites distant from densely populated areas (Staten Island). While amounts ranging from approri| mately 10 to 100 x 10~ gm/cu m of an** pled air may appear to be exceeding^ small quantities of asbestos, it is well If recall that chrysotile asbestos easily fat?, ments into ultimate fibrils 300 to 400 A i* diameter and often 2,000 A or snallef Sfi Dior to the imple: regulations, t lower Manhattan a vicinity of building wb.-re spray fireproo Dming materials wa iLiv - on which data > !.* levels in 10* g: ir. 1. downwind froi rite 2, 45 dowi ,.n i upwind from ot upwind from any sojvic.'l from a spray t upwind from any soui Tlie data in New r i tod by measuremt ; iore rural areas. r f dr in three sele< f"i!..vvs: Philadelphia !' 11 in 10* gm/cu n i t- -tos level in 10~ Ml. j.tny. Pa, 10 to 1 ' gm/cu m (amt '"imd in the air of thi r. nring this material These data, though -~r.il .Hsh that, at least t '-r is a background of the ambient '** higher about consti ' Much more ini ;ir,d. however, befo ' "v t*. made concemii ' '"oh contamination. During this procedure, those chrysotile fiber bundles present are broken into their elementary fibril form. The grid is scanned at 42,000 X in an electron microscope. Typ length. Thus, 10* gm of chrysotile tos could represent a million fibrils. ' That Manhattan has higher levels of*J; bestos than other boroughs is to be expedMj. Epidemiologies Knvironmental Diset J i -bestos pollution ically, six grids are prepared of each sample, as greater use of asbestos in building and three 100/i X 100/i squares of each grid struction takes place in that borough. ^ tahlished. What has '"\>ver, are the dir are scanned. The mass of asbestos is ob ing the past1 twemn yyeeaarrss,, iut huaass bueceenii conimg* 'hi. !i may be associate >N0TE: THIS DO IEMT DIDArch Environ Health--Vol 25, Jul mNOoTt nCOnuMcE i'EroSIrTMw 'PR FILES oo^srri-- 'F ET AL ASBESTOS AIR POLLUTION--SELIKOFF ET AL 11 suring the volume of asbes^ctice to spray fireproofing material con 's aM^-nultiplylng by the lining from 10% to 30% asbestos, onto >t>^B/ure 4 shows sev^^ers, spandrels, and decking of high-nse in anambient air sample!^ce buildings. Often, inadequate precau- n microscopy. Usually, o0ns were taken by contractors to contain f any, are observed in spray material and extensive "snowfalls d. ^ asbestos-containing material took place one takes samples m^ver widespread areas of Manhattan. This tos, more large fiber bundw&ctice was of such obvious concern that he initial sample. As thtjjew York City has banned the spraying of ring sample preparation, i^bstos fireproofing, effective as of Feb 26, groups of fibrils remain i j972.a5 *e of these bundles, or evi prior to the implementation of New York -imps, gives rise to a van City's regulations, data were obtained in 'tuples greater than or lower Manhattan at various sites in the n statistical considerate vicinity of buildings under construction he scanning of many gr, where spray fireproofing with asbestos-con- verage their effect tabling materials was used- During the two tial Investigations.--A days on which data were obtained, the as* ere measured at vario bestos levels in 109 gm/cu m were as follows: City. These samples we vie 1, downwind from a spray source, 45 to ocations of the sampli gO; site 2, 45 downwind frcm one source ^rk City's Department and upwind from others, 15 to 30; site 3, sites were all located o upwind from any source, 20; site 4, down- istant from a_ ,_nvy kiuniouwnj wind from a spray source, 45; and site 5, " asbestos. The chrysotiij upwind from any source, 20. air in the various satr as follows: Manhatta' leve" m 10*9 gm/cu ir bes^^ir level in 10 13^^22, asbestos ai The data in New York have been supple mented by measurements in other urban and in more rural areas. The chrysotile content of air in three selected locations was as m; Queens, 18 to 2J i l(h* gm/cu m; aw follows: Philadelphia, 45 to 100, asbestos level in 1CH* gm/cu m; Ridgewood, NJ, 20, asbestos level in 10** gm/cu m; and Port 21, asbestos air low While preliminary Allegany. Pa, 10 to 30. asbestos level in 10~* gm/cu m (aroosite fibers were also urn jviannattan tendec trndjn the air of this community, a * 3 from other borough rr using this material was presgL-- to ually from sites nw `-These data, though bUi]J populated business establish that, at least in the ~,ntami- ging from approxi 9 gm/cu m of sanv to be exceeding^ 'estos, it is well to isbestos easily frafrils 300 to 400 A V 00 A or smaller ir to i, . bsckgrom,d of lotion of the ambient eir and ftat be higher about construction sites in urban areas. Much more information wlU quired, however, before reliable *"""*?* can be made concerning quantitative levels clsuch contamination. of chrysotile a^be1 `on fibrils, Epidemiological Perspectives higher levels of asis is to be expected s in building con hat borough. Dot' has been comr.wr ivironmental Disease.--The occurrence f asbestos pollution of urban air is now riablished. What has not been defined, knvever, are the dimensions of disease *bich may be associated with this pollution. Indeed, it is hardly proper to speak of "as bestos air pollution" in general terms. There are different sets of circumstances in which such pollution can occur, varying in inten sity, intimacy, and duration of exposure. Lapsed Period.--A problem common to all types of asbestos air pollution is the long lapsed period between onset of exposure and appearance of disease. In general, this is 20, 30, 40, or more years insofar as neoplasia is concerned. There are variations, of course. It may be that intensity of exposure is one such variable; others could include fiber va riety, fiber size, competitive risk of asbestosis,6 cofactors such as cigarette smoking,15 trace elements, and perhaps other concomi tant air pollutants. Defined Populations.--It should be recog nized that the different kinds of asbestos air pollution are not limited to well separated compartments. Exposure to general commu nity asbestos air pollution may be over whelmed by indirect occupational exposure, in the case of a construction workman. Simi larly, the asbestos inhaled by virtue of fami ly contact in the household of an insulation worker could hardly be attributed to the scant asbestos fibrils in the air of a rural community in which that employee hap pened to live. Such permutations are com mon and may be misleading unless identi fied. When considering neighborhood air pollution about an asbestos plant (30 years ago, since it would be these people with whose fate we would now be concerned) it is well to remember that, at least in the 1930s and 1940s, people who worked ih a plant tended to live near it. Thus, the population about a plant being studied would have to be well characterized, to identify those with direct occupational exposure, before the ef fects of neighborhood contamination could be evaluated. Sources and Control Sources for asbestos air pollution can be looked at in two ways. They can be identi fied and measured without reference to ex posed populations. Epidemiological atten tion may then be attracted to these "con tamination sources in search of disease." Alternatively, sources for asbestos air pollu tion can be studied in relation to their po tential for exposure of human populations. C3 CO iJj CO ,1 1 i CD ZJ f*-*'^ Z2 ji L!~ 5:r./j L'J T'** h-- o dJ o y-- oo Arch Environ Health--Vol 25, July 1972 r*, . fi-: r * 12 ASBESTOS AIR POLLUTION--SELIKOFF ET AL At this time, both approaches are ham pered by inadequate information on the relative significance of peak exposures com pared to constant background contamina tion. There is clinical evidence which indi cates mat heavy exposures for brief periods (days, weeks, months), with retention of the inhaled fibers for the rest of the individ uals lifetime, may carry serious disease potential37 Therefore, intermittent high peak exposures may carry an unusual risk, especially when added to the cumulative retention associated with background pollu tion over long periods of time. Adequate information is needed concern ing the natural history of asbestos air pollu tion, including persistence, variations with meteorological conditions, and ultimate fate.38 Asbestos fibers, being mineral, may persist in the environment for long periods. It is not known, however, if this is so, or to what extent attrition occurs by a variety of physical processes. We have found amosite asbestos fibers in the settled dust and in the household air, within homes which had been occupied 15 years before by workmen of an amosite^actory, Similarly, both settled dust and ambient air in a constmction work man's home contained chrysotile fibers at levels beyond those usually observed as background. Neighborhood contamination from factory sources may also be associated with long persistence of the mineral fibers. In preliminary studies, we have found tms to be true ot Doth superficial sou contamina tion and settled dust on attic rafters in sucH neighborhoods. It is apparent that informa tion concerning persistence and fate of as bestos air pollution would be important, if only as a background to the evaluation of air levels from current emission sources. Natural Sources of Asbestos Air Pollu tion.--It is likely that some air contamina tion occurs from natural sources. Serpentine rock outcroppings occur in many parts the United States and other coun Studies in our laboratories suggest that, an ultramicroscopic level, serpentine frequently contains some fibrous components, which are properly cla chrysotile. In addition, some outaroppi contain frank chrysotile veins. Such tile-containing rocks are widely dis although not necessarily in coi concentrations. Nevertheless, abrasion weathering of such surface formations be accompanied by release of chrysotile bers into the surrounding air. Industrial and Commercial Sources.though natural sources for asbestos ab lution should be considered, it is likely they add only an infinitesimal amount the asbestos air burden in urban areas. Mi is derived from commercial and ind sources. Here, emission-source inventori can be prepared and would include port and storage of raw fiber supplies, ufacture of the many useful asbes taining products, transport and end-use <& these products, their weathering, and ulw mate disposal as waste. In general, the po$ tential for pollution varies with the di----- of fixation of the fiber in the product. Approximately two thirds of the ashes: used in the United States is used in struction products. Ship building and and waste disposal of asbestos products important areas for study. Spraying of bestos-containing mineral fiber insulati has already been mentioned. Factory sions are an obvious, and controllable, culty. Housekeeping in all asbestos-using cilities may turn out to be a knotty problenSFlJj and ultimately associated with much as tns ab pollution. This investigation was supported in part by Health Service grants OH 00305 and ES 00358. Dr. Linger was the recipient of Career Award ESC 44812. Ii and peritoneum I,,, m the London area. 1965. - Ueben J, Pistawk. i.-Hi- exposure. Arch Thomson JG, Kas< Ul-r-tos as a modem - 7 81, 1963. in Gross P, Cralley ti.. bodies: Their nonsg l-,-J 28:541-542. 1967 11. Williams E: "Cu limes of coal-workers. Li 12 Selikoff IJ, Churg .-\|aisure and neoplasia. ! i. Selikoff IJ, Hamr r'tm-ui-e, smoking and II.' 1968. I t Selikoff IJ, Hamr u experiences of ask* >`i .iro HA (ed): Proc i m/erence on Pneurn \t I, n, Oxford Universit 1.7 Hygiene standard 1-.-; Occup Hyg 11:47-41 bl. Selikoff IJ, Hamr non-occupational er iso. Amur J Public He- 17. linger AM. Selii tos in the lungs o i - h Environ Health 22 1H. linger AM, Bad Inorganic fibers, inclui -uiu|>sy: Preliminary r / ',nled Particles and \ os Ltd, 1971, vol 2, pf II * linger AM, Mi invsotile asbestos fibn - ix.itions. Amer Miner. -D. Pooley FD, Oldh ii-iu-tion of asbestos '-ll: Proceedinga of t '. 1`neumoconioais. Cai I niversity Press, 1970, Sundius N, Bydg '-l^|"tosis-Iungen und d b'-r inbestosis - korperc ?)-:W. Beattie J, Knox '1' and particle size ^3-.os textile workei References L Kiviluoto R: Pleural calcification as roentgen ologic sign of nonoccupational endemic enthophyllite-asbeetoeis, Acta Radiol, ouppl 194, pp 1-67, 1960. 2. Jacob G, Bohlig H: Roentgenological complica tions in pulmonary aabeatonia. Forttchr Reontgenatr 83:515-525,1955, 3. Selikoff U: The occurrence of pleural calcifica tion among asbestos insulation workers. Ann NY Acad Sd 132:351-367,1965. 4. Laamanen A, Noro L, Raunio V: Observa tions on atmospheric air pollution caused by asha* _ too. Ann NY Acad Sd 132:240-245, 1965. Wg 5. Wagner JC, Sleggs CA, Maichand P: Diffw*, pleural mesothelioma and asbestos exposure North Western Cape Province. Brit J Induttr 17:250-271, I960. 6. Weiss A: Pleurakrafas bei lungenaobestoaa, vivo morphologisch gesichert. Medizinitche 1:'"' 1953. 7. Newhouse ML, Thompson H: Mesothelioma--* In a recent a Monitoring of third line of col Arch Environ Health--Vol 25, July 1972 ET AL * oj'-v'- in many parts 0 tes^^. other countrii-. xn^Res suggest that, on lie level, serpentine verv ns some fibrous mineral n are properly classified as iition, some outcropping /sotile veins. Such chryso ks are widely distributed, -cessarily in oomnxrci.il svertheless, abrasion and i surface formations might y release of chrysotile f,. aiding air. Commercial Sources.--At .trees for asbestos air polsnsidered, it is likely that infinitesimal amount to rden in urban areas. Most tmmercial and industrial tission-source inventories aid would include trniwf raw fiber supplies, manany useful asbestos-con transport and end-use <>! air weathering, and ulliaste. In general, the n varies with the degree ter e product <vo of the asbestr* i SrHfe is used in con Ship building and repair, of asbestos products an1 r study. Spraying of a.nineral fiber insulation lentioned. Factory emW s, and controllable, eliffi ; in all asbestos-usim: fa t to be a knotty problem, dated with much a>lx>- s supported in part by 1 *ul*l> 00305 and ES 00358. ecipient of Career I.' r pollution caused bv 132:240-245. 1965. s CA, Marchand P: I liilier and asbestos exposure ir rovince. Brit J lndustr tff'- -ebo bei lungenasbesti'se. v .chert. MedUinische 1 93 3* ompson H: Mesothelioma d ASBESTOS AIR POLLUTIONSEUKOFF ET AL 13 and peritoneum following exposure to aabeaj in the London area. Brit J lndustr Med 22:261I:\1S65. g Lieben J, Piatawfca H: Mesothelioma and aa- exposure. Arch Environ Health 14:559-563, [$. Thomson JG, Kaschula ROC, MacDonald RR; as a modem urban hazard. S Afr Med J 77-81,1963. [0. Gross P, Cralley LJ, doTrevitle RTP: Asbes- bodies: Their nonspecificity. Amer lndustr Hyg oc J 28:541-542,1967. I'll. Williams B: "Curious bodies" found in the of ooal-workers. Lancet 2:541-542, 1934. 12. Selikoff IJ, Qmrg J, Hammond EC: Asbestos ire and neoplasia. JAMA 188:22-26, 1964. Selikoff IJ, Hammond EC, Churg J: Aabestoa ISsrpoaure, smoking and neoplasia. JAMA 204:1061968. 14. Selikoff IJ, Hammood EC, Churg J: Mortaliexperiences of asbestos insulation workers, in iShapim HA fed): Proceedings of the International ^inference on Pneumoconiosis, Capetown, South i, Oxford University Press, 1970, pp 180-186. -15. Hygiene standard tot chrysolite asbestoa dust. Ckcup Hyg 11:47-49,1968. :16. Selikoff IJ, Hammond EC: Community effects t non-occupational environmental esliestos expo sure. Amer J Public Health 58:1658-1666, 1968. ** 17. longer AM, Selikoff IJ, Sastre A: Chrysotile jsMbestoa in the lungs of persons in New York City. mhrch Environ Health 22:348-361, 1971. 3"1& longer AM, Baden V, Hammond EC, et al: Snorganic fibers, including chrysotile. in lungs et nautopsy: Preliminary report, in Walton WH (od): hinhaled Particles and Vapours, ILL London, Unwin SBroR Ltd, 1971, vol 2, pp 683-694. y119. Longer AM, Mackler AD: Morphology of ^sbrjraotile asbestoe fibrils: Electron microscopic obSeervations. Amer Mineralogist, to be published. toV20. Poolev FD, Oldham PD, Um CH. et al; The Snetection of asbestos in tissues, in Shapiro HA tsd): Proceedings of the International Conference Pneumoconiosis. Capetown, South Africa, Oxford liveiaity Press, 1970, pp 108-116. 2L Sundius N, Bydgen A: Der staubinhalt einer -lungen und die beachaffenheit der sogenn- sbestosia - korpercben. Arch Gewerbepath 8:26,0938. Beattie J. Knox JT: Studies of mineral connd particle aim distribution in the lungs of textile worker*, in Davies CN: Inhaled Particles and Vapours. New York, Pergamco Press, 1961, pp 419-433. 23. Bohlig H, Dabbert AF, Dalquen P, et al: Epidemiology of malignant mesothelioma in Hamburg: A preliminary report Environ Res 3:365-372, 1970. 24. Borow M, Constan A, Livomese LL, et al: Mesothelioma and its association with aabestosia. JAMA 201:587-591, 1967. 25. Raunio V: Occurrence of unusual pleural cal cification in Finland: Studies on atmospheric pollu tion caused by asbestoa. Ann Med Intern Fenn 55 (suppl 47): 61, 196a 26. Zolov C, Bourilkov T, Babadjov L: Pleural asbestosia in agricultural workers. Environ Res 1:287-292. 1967. 27. Burilkov T, Michailova L: Asbestoa content of the soil and endemic pleural aabestosis. Environ Res 3:443-451, 1970. 28. Hromek J: The mass incidence of characteris tic pleural changes in citizens of the western part of the former Jihlava region. Rozhl V Tuberh 22:405515. 1962. 29. Rous V, Studeny J: Aetiology of pleural plaques. Thorax 25:270-284, 1970. 30. Dreessen WC, Dallavalle JM, Edwards TT, et al: A Study of Asbestosis in the Asbestos Textile Industry, bulletin 241. Public Health Service, .1938. 31. Sped S, Leineweber JP: Asbestos minerals in modem technology. Environ Res 2:166-208,1969. 32. Lynch JR, Ayer HE: Measurement of asbes tos exposure. J Occup Med 10:21-24, 1968. 33. Turkevicb J: The world of fine particles. Amer Sci 47:97-119, 1959. 34. Berkley C, Churg J, Selikoff IJ, et al: The detection and localization of mineral fibers in tissue. Ann NY Acad Sci 132: 48-63, 1965. 35. Spraying of Asbestos Prohibited, local law 49, in Air Pollution Control Code of the City of New York, sec 1403. 2-9. 11 (b). New York City Dept of Air Resources, Aug 25, 197L 36. Jacob G, Anspach M: Pulmonary neoplasia among Dresden asbeetos workers. Ann NY Acad Sci 132:536-548, 1965. 37. Selikoff IJ. Bader RA, Bader ME, et al: Asbestoeis and neoplasia. Amer J Med 42:487-496, 1967. 38. Asbestos: The Need for and Feasibility of Air Pollution Controls, Committee on Biological Effects of Atmospheric Pollutants. Washington, DC, Na tional Academy of Sciences, 197L sc-'-IJ r.lf) N . wW ERRATUM In a recent article by Sherwin and Yuen, "Silicone Fluid for the Metering and j -- Monitoring of Nitrogen Dioxide" (24:331, 1972), the number "5.23 ppm" in the third line of column 1 on page 331 should read "3.93 NO,." Arch Environ Health--Vol 25, July 1972