Document v1YxwREBVeZrRvJ0a6LgMzdNR

PLAINTIFF'S EXHIBIT 0<- ' /v\ 4 HGfi Martinez JAN 2 6 1976 asbestos: rationale behind a proposed air quality standard Leonard Bruckman and Robert A. Rubino Connecticut Department of Environmental Protection The following discussion presents a proposed asbes tos air quality standard and'lho rationale utilized in .its formulation. The criterion of mesothelioma has boon solpcted as tlie basis for developing the subject standard. A concentration mesothelioma incidence envelope has been constructed for the general popu lation, based on mesothelioma incidence due to in dustrial exposure. An ambient air quality asbestos standard of SO nanograms per cubic meter, based on a SO-day average sample is recommended. This stan dard is projected to result in Inti nationwide fatali ties. Available ambient air asbestos data indicates that non-urban and remote non-urban areas have as bestos levels typically less than 1 nanogram per cubic meter while urban areas are usually below .'10 nanograms per cubic meter. Dispersion calculations are used to determine the maximum allowable asbestos mass emission standard for manufacturing sources tl't grams per day) and a maximum allowable average asbestos concentration (2.r micrograms per cubic meter). A family of curves for various workdays depicting the average allowable asiiestos concentration as a function of total asbestos contaminated exhaust gas flow rate, consistent with the 24 grams per day emission standard are present ed. In addition, a preliminary asbestos stack sam pling train has been developed requiring electron mi croscopy as the analytical procedure to be used to de termine the sample asbestos content. The implementation of the proposed emission standard'will lower the expected annual asbestos emissions from manufacturing operations in Con necticut to below one ton compared to the 10 tons emitted if the Federal EPA asbestos regulation is ac cepted. The proposed air quality standard will fur ther reduce Connecticut asbestos-related fatalities to only two persons annually. "Asbestos," the generic name given to n variety of fibrous, silicate naturally occurring minerals, is present as an invisi ble am! anonymous ingredient in a myraid of industrial products, sudi as paint, floor tiles, gaskets, cement, shin gles. pipes, brake linings, fireproofing and insulating mate rials. and asbestos fabrics. The principal variety of asbestos used in industry is chrysolite (greater than with mrais- ite and crncidolite being of lesser significance. Consump tion of asbestos in the U. S. has risen from approximately .to.oon tons in IfKiA to nearly 800,000 tons in the early 19?0's, about a 20-fold increase.1-2 1207 ASARCO ALV 0007492 Health Effects--Occupational It has been well known fur nearly half n century that some persons subjected to asbestos (lust during work (leveloped a severely crippling arid someliines fatal limp disease, called nsliestosis. Asliestosis can lie elassified ns nn nceupnlionnl disease whirh oeetirs after relatively heavy exposure to asbestos fiber dusf. The use of antibiotics in (be 19,'10's dramatically reduced the death rate from infectious pulmo nary diseases that often had to be feared as a complication of asbestos; consequently, asbestos workers instead of dying from nsliestosis, began living long enough to develop asbestos-induced cancer of the lung, gastrointestinal tract, stomach, and especially the lining of the stomach and lung fi.e., mesothelioma).11 Asbestos has become one of the largest industrial enuses of cancer in the world/' All the commercially used forms of asbestos can produce asbestosis, ns well ns the types of cancer previously mentioned. Mesothelioma was regarded by pathologists, until re cently as an extremely rare disease and at times, a medical curiosity. In !9fi.rt Dr. Selikoff and bis associates conclusive ly proved a causal link between asbestos filler exposure nnd mesothelioma/''" A significant nnd somewhat frightening feature of mesothelioma is the extended lag period between first exposure to asbestos fibers nnd the first symptoms of this form of cancer. It has been reported in the literature thnt this time period may be anywhere from 20 tn fOymrs.K ,n This long time interval emphasir.es the Intent insidious problem asbestos fiber exposure continually creates for in dividuals, both occupationally nnd nan-accupalwnally ex posed. Health Effects--Non-Occupatlonal Evidence that people other than those working directly with asbestos were also being subjected to asbestos fibers was of several types. In a few geographic regions where as bestos was mined and milled nnd asbestos-containing prod ucts manufactured, pathologic alterations fi.e.. pleural cal cification) were discovered in populations with no history of occupational exposure." Keren! studies have indicat ed that urban dwellers harbor high quantities of asbestos fibers in their lungs.:,-"'":- ,K The most serious implication of the hazards of noti-occupntionnl asbestos fiber exposure is the risk of contracting mesothelioma. Several studies have done much to verify the connection between asbestos fiber exposure and the in cidence of mesothelioma among the general population.',','l!,',' Current cases of mesothelioma must he associ ated with asbestos fiber inhalation that took place 20, 00, or more years ago, when world consumption of asbestos was only about 500,000 tons/year, and that neoplasms associ ated with today's annual production of over -1,000,000 to will not he evident until the 1990s. The health hazard th asbestos fiber exposure poses to the general public is cor pounded by the synergistic effect of tobacco smoke, ar possibly other air pollutants, such as benzo(o)pyrene.9 Relationship between Occupational Asbestos Exposure an Incidence of Mesothelioma The Federal EPA has recognized the need to control tl emission of asbestos fibers into the ambient air and has r< cently promulgated National Emission Standards for Ha nrdous Air Pollutnnts (Asbestos, Beryllium, and Merci ry).21 Alternatives to the EPA's required control strategii are conceivable and the following discussion presents or such option, the formulation of nn asbestos ambient a quality standard and a compatible mass emission standar for manufacturing sources of asbestos emissions. The probability of a person in the general communit contracting mesothelioma has been chosen as the basis fc developing the asbestos air quality standard. Most of th information presently available on exposure to asbestos ha been collected in industrial environments. Studies present ly available on mesothelioma incidences due to industrii exposure do not report the fiber concentration to which af fected workers were exposed; however, a study by the Ne tional Institute for Occupational Safety and Healt fNlOSH) reports short term fiber concentrations for number of industrial settings.22"215 While these short terr. fiber concentrations are of recent origin and as such are no directly related to the epidemiological studies of mesotheli oma incidence, they do reflect the difference between wel and poorly controlled processes; and thus can be used as ai estimate of low or severe exposure.2'1 Table I summarize mesothelioma incidence data from several different studie along with high and low concentrations from the NlOSh document for shipyards, textile processes, construction op erntions, and insulation plants. These data were used t< construct a concentration incidence envelope, depicted ii Figure 1. Relationship between Fibers Greater than Five Microns to Nanograms o( Asbestos Asbestos fibers monitored in industrial settings (greater than 5 pm in length, length to width ratio of greater than 3) using phase contact (PCI light microscopy (4.10X magnifi cation) account for approximately 2% of all asbestos fihers present (by number).27 Hence, In the occupational environ ment every asbestos fiber greater than 5 am in length cor responds to an actual fiber count of 50 (i.e., 1/0.02 = 50). omo !.i|i|i* I. In- rl- ii. , i,l lm-v,lli,-)tntii.i .mi! -i-.Ih- -tn\ i*mi ciilr.itinne tn nil up.itlim.ll . ............. 11 t ..ii.-ii-t NlHtltuM f iiitlivuiti.iU U, .. tin 1"in 1 till IlliMUt' lU'li'H'iui* Itii'.lii-ot' l.mvi M >' avit.ijii* .UIT.UV i utti i'll (III (Ml trjtioit irjitioti (liter/ filler/ cm* on' 1*1 -M1 11 Mf % pl.IMJS Slops l-.l. * n.*, 1 > \iilr pi iiit\ r,.VM .toon (. 12 :w. | \IHI - | Xnn 2 IS n ;t n t t 1 =-0 l nn l .'ii CM) r.M\ (JM n. *2`*1 :-'tt.(2D 2U, (im 121). IP 7-1.4 K.7 7.1 M.O 2).n 0.1 ti.n o.t n.l O.I * \|... i .,I 11,,- ii..),, ,,1,|.,|. n, *' t ............. ni.,ii. 11,,in JV|t ts| | It.,it In-, n t,ll,iw,-*t lot ?0 visits nr lunger. mm-til,11 Iniirnal Af tho Air PnllutiAn P.Antrnl AcnrialiAf' ASARCO ALV 0007493 10 Hypothetical probability ol contracting nicscllieticm.1 Figure 1. Expected incidence ol contracting mesothelioma as a function of Industrial air asbestos exposure (8*hr day. 5 day week).33 Amblont Air Asbestos Standard Now lhal a scI of curves relating the nationwide expect ed cases of mesothelioma ns a function of nmhient air as bestos expsmire hns been constructed, a desired ambient air asbestos level can he decided on. This was accomplished by investigating the total number of nationwide fatalities attributed to automobile, aircraft, and railroad accidents for the year 1972. The minimum line (this reflects the smnllest possible probability of contracting cancer) of the concentration-mesothelioma incidence curve was used. An ambient air asbestos standard of 20 ng/m1 was chosen. This level should result in about 1/10 the total nationwide num ber of fatalities (approximately 150) from airplane acci dents and approximately the same number of deaths as from train mishaps; the maximum line, or greatest proba bility line, would have yielded over 100,000 expected fatali ties. The use of the minimum line instead of an average line wn chosen ns a reasonable basis for setting the ambient air asbestos standard in order to account for some of the as sumptions made in developing the concentration-incidence envelope. I)r. Thompson (personal communication) reported that thpro are about 1000 total asbestos libers per nnnogrnm of asbestos.'78 Therefore. 20 asbestos fibers greater than 5 yrm lonp have been assumed equivalent to one nanopram of as bestos (i.e., 1000/50 = 20). This appears to he a reasonable nssumption sinre Lynch and his co-workers reported, based on',magnesium determinations, that for certain manufac turing operations, one tip of asbestos was equivalent to 6.7 to 22.5 fibers greater than 5 pm lonp as determined by PC.27 Relationship between Non-Occupatlonat Asbestos Exposure and Incidence of Mesothelioma 'The mesothelioma incidence envelope depicted in Figure 1 appears as a fund ion of both fibers greater than 5 am in length and ng of nshestos/nv'. respectively. Occupational exposure concentrations, which are based on an 8 hr dny, 5 day week must now he related to exposure levels for the general public (2-1 lir day, 7 day week) which conlains'-many susceptible groups, such as the plderly and infants, who must nnii-voluntnrily and continuously endure the ambient environment. This can hr accomplished by di viding the occupational exposure levels by 4.2 (24 hr/8 hr X 7 dnys/5 days= 4.2).17 A coneeotration-mesothelioma inci dence envelope for nmhient air asbestos exposure for the general public has thus been constructed, as shown in Fig ure 2. c 10 oC n Proposed Sco 10 'J30- standard ' ------- Mir* 10 / /! Max i __ , i.. 10 to* 10* I 10J 10' 10 ` 150 Nationwide expected cases of mcsothMioma 10 Figur* 2. Nationwide r*ppctrd of mnsoihnhoma ns n (unction of ambient air asbestos cposwo (assumed popula* (ion of United States was 230 roMon people) Ambient Air Asbestos Levels How reasonable is the desired ambient air standard of 30 ng of nsbestos/m *? Nonurbnn and remote nonurhnn air borne asbestos concentrations are typically less than 1 ng/ mY-'K Urban areas usually have asbestos concentrations below the desired 30 ng/m1 standard except in heavily in dustrialized areas (e.g., Manhattan, N.Y.C. and Philadel phia), around construction sites and toll booths.28''1'1-'14 The desired standard appears to be reasonably set and attain able. Comparison of OSHA and Ambient Air Asbestos Standards The proposed American Conference of Government and Industrial Hygienists (ACGIH) Occupational Standard of 2 fibers greater than 5 am in length/cm1 (or 2//cm:l X 10B cm'/m:l X ng/20f = 10'' ng/m1) is designed specifically to prolect the workman from contracting asbestosis, which re sults from hravy occupational exposure to asbestos. This standard does not take into account the effect of asbestos as a carcinogenic agent.8'7- The OSHA standard is equiva lent to a general public exposure of 25,000 ng of asbestos/ m:l (i.e., 10Y4.2 = 25,000hjt is concluded that the proposed standard of 30 ng/m:l is not unreasonable even though it is approximately 1/1000 of the OSHA standard, since the lat"terstandard is riot nearly stringent enough to protect work men from contracting cancer. Asbestos Emission Standard Figure 3 depicts the maximum allowable emission rnle (consistent with the desired 30 ng/m1 nmhient air standard based on both a 24 hr average and 30 day average sample) at corresponding distances from n source. These emission rale curves were constructed using dispersion estimates and local Connecticut meteorological assumptions.14 1,: Thus, the maximum allowable emission rate, consistent with the aforementioned assumptions, would he either 20 or 24 g/day. respectively, at a distance of approximately ei ther 300 or 350 ft from the source. A 24 hour sampling peri od is not really long enough to reflect properly the average nmhient asbestos levels in any region and is very sensitive to short term asbestos emissions. An ambient sir standard based on a 30 day average sampling period is more manage able from n monitoring standpoint and more descriptive of the average ambient air asbestos concentrations for a par ticular area. It is therefore concluded that the ambient air 1209 ASARCO ALV 0007494 I Figure 3. Calculated maximum allowable asbestos emission rale as a lunr.tion ot distance from source (assumed 4 m/sec wind speed, 10m effective slack height, 40% fre quency factor tor wind direction, and C stability class). asbestos standnrd should be based on a 20 day average sample and the corresponding maximum allowable asbes tos emission rate is 24 g/day. The aforementioned emission and ambient air quality standards result in a maximum daily inhaled asbestos dos age of GOO ng, (20 nv'/day (total average adult daily respira tory air intake) X 20 ng/itr' = GOO ng/day). However, under adverse local meteorological conditions a person walking near or close to an asbestos emission source might be "subjected to the same asbestos concentration as that of the plume itself for a short period of time. In order to protect such an individual the maximum allowable average asbes tos plume concentration could be limited to 25 gg/m*. A person walking "through the plume" will then experience an asbestos concentration for a 15 minute time period equivalent to 10 times his mnximum allowable daily dos age. Figure 4 depicts the average allowable asbestos concen tration as a function of asbestos-contaminated exhaust gas flow rate for various periods of daily plant operation con sistent with a maximum allowable emission rate of 24 g/day and the desired air quality standard. This Figure could he utilized as an emission standard of sorts; the larger the as bestos-contaminated gas flow rate the lower will be the al lowable average asbestos plume concentration. Manufacturing Sources of Asbestos Emissions A survey of nshestos users in ('onnerlirut, summarized in 'fable If, indicates that annual state uncontrolled asbestos emissions could amount to almost 20(1 tons. Comments so licited from manufacturers of particulate control equip ment, in addition to other reports, indicate that there should bn no problem in obtaining at least a 115% asbestos emission control efficiency using cither a high energy scrubber or n fabric filler and in many instances control ef ficiencies ns high ns Hil.H'S. are attainable. It should be un derstood that there is scant actual supportive test data available: however, the criterion used to support the quoted efficiencies (experience with similar fibrous material dusts) should be valid.-1*-1'* Notwithstanding the employment of best available asbestos control technologies ns required by the Federal HI*A asbestos regulation almost 10 tons of as bestos might he emitted into the Connecticut atmosphere each year ns a result of mauufacluring operations. In order to evaluate properly the potential hazard of this airborne asbestos it is iinnorlnut tu tmrliTHtiiiirl tlint I i' nf ns rrnilrl contain it)) Id l,(K)l),(KXI.OOO iishustiiK fibers mi inhaled ntlu-tlns liber coufr? priti'iilinto n cancer. 'i'l plementntion of the proposed 24 g/day emission sin in Connecticut would lower the exported annual asl emissions from manufacturing operations to below and, thereby, provide the impetus for the developrm improved asbestos air pollution rontrol equipment. I dition, greater than 9f% of the sources should has problem meeting the proposed emission standard em ing state-of-the-art control technology. Brake Lining Decomposition Asbestos as a result of brake lining decomposition r. contribute another 1.5 tons of airborne asbestos fibers the Connecticut atmosphere each year.:1-:1!,'4:i Several ii tigntors have suggested that the asbestos emitted as suit of brake usage is not a significant source of atmosf ic asbestos; however, in New York City air asbestos coi trations contiguous to a toll booth were 2 to 5 times I ground levels.4-1-44 Additional data are needed before impact of brake lining decomposition on airborne asbc levels can be ascertained. Demolition The demolition of ashestos sprayed highrise build could result in the emanation of a large amount of ashe fiber dust unless adequate precautions are taken. If thr heslos emissions caused by demolition operations coul< accurately accounted for the actual annual tonnage of bestos emitted into the Connecticut atmosphere might significantly increased. Asbestos Stack Sampling Train It has been suggested that an asbestos air quality regi tion which employs an emission standard will suffer fr the unavailability of an adequate stack sampling pro dure; however, other investigators report that there sho be no problems, either theoretical or physical in stack sn pling for asbestos than there would be in sampling r complex source.4'* The stack sampling train depicted Figure 5 (a modified version of the approved federal part ulate train) might be used to measure asbestos stack en. sions; however, this proposed train has never been fi< tested. Figure 4. Total asbestos contaminated gas (low rate as a function of allowable asbestos aic coocentcalioa.. ASARCO ALV 0007495 'faille II. A Miiwy | tiM*r\ lit T\ |V 1*1 1MMIT C A.l'i*.in-, tement, H...m tile .mil p.tpcr in In. f;rit (ton prnilm t mfp. *1 ovmIc iiifu. Mim in lp,, Veil it It* Iw.ikc limnc A < Inti It l.it inp ff tM*n 1 Vinoln i<m npci.itiitiM Niimln r of smin rs 17 4 12 in l,,sr, x in* T. I).ivi-.A Asmh.m 'J.ul.wf,,/.*'' ti in, I1*/.!. AnIw-.mh tIM (1. Mnts/yo.tr 600 Urn nntmllcd*! emission lor, Ib/tnn 4 I'otcntul iiiuomrolled cirmsimn, tniM/ycar 1.2 .1200 *100 0(10 N/A 120 40 10 <.10 uc.1mill**' 192 0.8 4.5 1.5 Unknown Unknown Unknown Analytical Asbestos Determination In the Inst few years, techniques fur determining ohrysn. tile ashestns concentrations (in terms of ng/m'l in the am bient air, based on electron microscopy, have been devel oped and used with a reasonable degree of suc- HARTICUIATC COHFCHON OCVICE December 1975 Volume 25. No 12 ross.-K,:n:,H,ll,,J IJr. Kelikoff and his associates report that the unique morphology of chrysotile asbestos makes posi tive identification possible by transmission electron mi croscopy and the use of. replicate analyses, repeated cali brations, and background measurements indicate that the accuracy of a given measurement is likely to be within 50% of the actual value and certainly within a factor of This technique should be more than adequate in determin ing the asbestos content of stack samples. Conclusion In conclusion, it is believed that a reasonable approach aimed at controlling the dissemination of asbestos fibers into the ambient air has been presented. It is recommended that the rate of nationwide sampling of ambient air asbes tos levels be stepped up and continued so as adequately to define the scope of the problem: studies around demolition sites and toll booths are particularly needed. In addition, epidemiological studies of persons who have died of meso thelioma would be useful since they would lead to a better definition of the maximum allowable daily asbestos intake. Acknowledgments Mr. Paul Norton. Air Pollution Engineer, Department of Environmental Protection, Engineering Section. Air Com pliance Unit, Hartford, CT, Dr. Robert S. Pogrund, Envi ronmental Health Resource Center, Illinois Institute for Environmental Qualily, Chicago, II,. Dr. Richard -I. Thompson. Chief. Analytical Chemistry Branch, U.S. Envi ronmental Protection Agency gave valued assistance. References 1. It. A Clillon. personal rominunicalinn. U. S. Bureau of Mines, I'Vliriiarv I, I97:t 2. It ,1. Sullivan and Y. C. Alhannssidas, Air Pnlliitinn Asprcts of /KfuvUii*. P. S. Department nf Commeree. National Technical Information Service. NTIS # PH 1HH OHO, 1989. 3. A'hrslti\ Srrd far and Feasibility of Air I'nllution Control':, Committee on Itiologir Effects of Atmospheric Pollutants, Di vision of Medical Sciences, National Research Council, Na tional Arademv of Sciences. Washington. I). C.. 1971. 4. I. .1. Selikotf. C. Hammond, and ). Cliurg. "Cnrcinogenicily of amosite asbestos." Arch Failrun Health 25: 1H.'I (19721. 5. K It. Itoucot. W. Weiss. H Si'irlman. W. K. Carnahan, and I). A. Cooper, "The Philadelphia Pulmonary Neoplasm Research Project: liasie risk factors of lung canrer in older men," Am. J. Kpidrntml 95:4(1972) i911 ASARCO ALV 0007496 R 6. I. .1. Srliknff, .1 rimrK, unit K. (` (Immunol "Relnlmo be tween exposure of ii'.hestns nnri mesothrlton Seir Enp ./ Afrti 272:560(196(1) 7. R. Sherrill, "A*Jic*1ns the viver of lives. h/i** n demllv **ide," #V V. Times Mnpaztnc Serhon pp 12 1.1. 58 1*4 (Jmumrv 21, 8. Hazards of Ashe\tos to Human Health, Minnrsotn Public He* search Interest droop. Minneapolis, MN. 1972 0. I. .1. Selikoff nnd K ('. Hntnmnnd, "Environmental epidemiol ogy, HI. ('nmonmtlv effects of nmt mi itpnlionnl environtnen* Ini asbestos exposure," Amor ) f'uhl Health 59: 1658 (1968). 10. .1. (\ Wagner, "Epidemiology of diffuse mesothelinl tumors: evidence of nn association from studies in South Afritn nnd the United Kingdom." Ann S V Arad Sri 1.12: 575 (1965). 11. T. Ashcroft and A (. Heppleslon, "Mesothelioma nnd Asbes tos on Tyneside1 A Pnthologirnl Social Study," in Fneumoconifiwv. Pmvrt'dtni** of the International ('onferrnce, .Johanneshurtt, H A. Shapiro fed.). Oxford University Press. ('ape 'I own. South Africa. 1070. 12. .1. Hromek. "The mmn incidence of characteristic pleural changes in citizens of the western part nf former Jilnlara He* ginn." ttnzhl "Tuherh 22: 10.1 (1962). 1.7. It Kivilunfo. "Pleural calcification ns a roentgenologic sign of nun-occupational Endemic Anthophyllite-Ashestosis," Acta Itadiol Suppl 101: I (I960). 14. L. O. Meurmnn, "Asbestos bodies and pleural plaques in a Finnish series of nutop^v cases.** Acta Path Mtcrobiot. Scan (Suppl) 181:1(1966) 15. V. Hnnnio. "Occurrem e of unusual pleural calcification in Fin land." Aim A/cd Inf Penn {Suppl 49)55:1(1966). 16. A. M. Longer and I..?, Selikoff. "(`hrysotile Asbestos in lamps of Residents of New York City," in Proieedinp.s of the Second International ('lean Air ('impress, M M. Enghmd nnd W. 7*. Heery feds.). Academic Press, NY, 1071. pp. 161-165. 17. I. J. Selikoff, \Y. .t Nicholson, and A. M. Lnnger, "Ashesti* air pollution." Arch Hnnron Health 25: 1 (1072), 18. M. I). Utidjiam. P. (ross nnd H. T. P. deTreville,"Ferruginous bodies in human loops; prevalence at random autopsies," Arch Knricon Health, 17,127(1068). 19. .1. Liehen and II. Pistnwkn. "Mesothelioma nnd asbestos expo* sure." Arch Enctrnn. Health 1 1:559 (1967). 20. M I#. Newhonse and H, Thompson. "Mesothelioma of pleura and peritoneum following exposure to asbestos in the London arent`*/irif ./ Ind Med 22:261(1965). 21. "KPA sets final emission standards for asbestos, beryllium and mercury," ). Air Toll ('ontrol Assoc. 2.1:198 (197.1), and Fed eral Itepister 28: (April 6, 197.1). 22. ('riteria for a Ilentmmended Standard for (h-rupntional Ex posurr, to Asbestos, U. K. Department of Health. Kdocnlion, nnd Welfare. Public Health Service, Health Services and Men tal Health Administration, National Institute for Occupational Safety and Health. MSM k "2-10267. Washinpton. IK*. 1971. 21. "Health Effect** and Recommendations fur Atmospheric Lend. Cadmium. MerrwVv. nml As|*Mos." Environmental Health Hesourees ('enter, Sfnte of Illinois Institute for Environmental Quality, Report M II KQ-77-2, Chicago. 1L. 1971. 24. H. ('. Lrwinsohn, "The medical surveillance of asbestos work ers."/foy Soc Health J 92:69-77 (1972). 25. M. L. New house, (5 Hrrry, 1. (\ Wnpner, and N. K. Turok, "A studv of the mortality of female asbestos workers," lint. ]. Ind 'Med 29: 114 (1972). 26. *1. Stumphuis, "Epidemiology of mesothelioma on Wnlcheren Island," Brit. J. Ind Med 28:59(1971). 27. .L H I.ynth, H. E Aver, nnd I). L. Johnson, "The tionships of selected md)0Ktn exposure indices," /. Hut J .11:598(1970). 28 U J 'I'hompson, personal rommuniention, prepri 7`hnmpson am! (. H. Morpan, "Determination of AtAmbient Air." May 2, 1971. 29. I. .L Selikoff, .1. Churg, nnd E. C. Hammond, "Ashes sure and neoplasia,"*/. Am. Med Assoc., 188:22(1964 10. M. L. Newhoune, "A nludy of the mortality of workers lienton fnctorv," Brit. J. Ind. Med 26: 294 (1969). 11. .1. F. Knox. K. Holmes, H. Do)!, nnd I. H. Hill, "Morin lung cancer and other causes among workers in an textile facility," Hrit. ). Ind Med. 25: 297 (1968). 72. W. Fulkerson and W. E. dueller (eds.), "Cadmium: T pnted Element" Oak Hidpe National laboratory, #0HNL*NSF*EP.2L0nk Hidpe,TK. 1971. 11. "Measurement of Asbestos in Ambient Air," Final Contract #CPA-70-92. I1. S. Environmental Protect!/ rv, Hesearch 'I'rianplr Park. N(\ 1970. 14. "Hnckpround Information on Development of Nation smn Standards for Hazardous Air Pollutants: Asbesto limn, and Mercury," l*. S. Environmental Protection Office of Air and Water Programs, Office of Air Quali nine *nd Standards, APTD-I503. Research Trianpl NC. 1971. 15. 1) B. Turner, Workhonk nf Atmospheric Dispcrsir mates. It. X. Environmental Protection Apency, Offic Programs. Hesrarch Triangle Park, NC, 1970. 16. (. Wight, personal communication, Connecticut mete <nl data. Connecticut Department of Environmental thin, 1971. 17. "Control Techniques for Asbestos Air Pollutants," U. momenta! Protection Apency, Office of Air and Wai prams. Office of Air Quality Planning and Standards, . Research Triangle Park. NC. 1971. 18. (\ F. Harwood, **Ashest>s Air Pollution Control," Stati n/iis Institute for Knvironmenta! Quality, IIEQ Dp ^71*8. ('hicapo. !L. 1971. 19. "National Inventory of Sources of and Emissions: A* Section HI," W. K. Davis and Ass/iciates, National Air lion Control Administration contract #22-69-131, P 252, Leawood. KS, 1970. 40. M. (. -inrkn, H. T. DuCharme. and J, H. Somers, "Hov asliestos do vehicles emit?," Auto East. 81:18 (1971). 41. M Ci. .Iack< and H. T. DuCharme, Brahe Emissions' Er Measurements From Brake and Clutch Linings from S< Mnhtlr Sources. Bendix Research Lal>oratories, U. S. Er mental Protection Agency report #68*04*0020, Sout ML 1971. 42. *L R Ivnrh, "Brake lining decomposition products." /V/ Control Awe 18:824 0 968). 41. A. K. Anderson. H. I*, dealer. R. C. McCune. and J. W. "Asbestos Emissions from Brake Dynamometer 1`ests." 710519 presented at SAE Automobile Engineering M Detroit, Ml, 1973. 44. W. .1. Nicholson. A. N. Rohl. and K. F. Ferrand. "Ashes* Pollution in New York City." in /Vcnwrfmgs of the Seco ternahonal ('Iran Air ('impress, H. M. Englund and Brerv. (eds.) Academic Press, New York. 1971. pp. 116-1 45. W. S. Smith, personal communication. Entropy Enviro talists Inc.. July 27.1973. Discussion Lawrence A. Plumlee, M.D. U S Environmental Protection Agoncy, Medicnt Scionce Adviser It is alwiiys easy tn (inti (mill with mintlur person's work, and it is dillicult to roint* tip with all mint ives which can not In* critici/crl wit h jn-t as much jn*-tiTication. Those of us associated with prcparinR the stanrlards and rcRulatinns for environmental protection are often faced with the necessity of doioR the host we can with a limiter! amount of informa tion. This is particularly trite when there is evidence (hat 1212 dnmnRp to the public health will result if we fail to Nevertheless, it is niy contention that Messrs. Brack and Bullion have made some maneuvers which render ! asbestos standards unsupportable. One nf these is thei: cision to base their standards on the risk of mesotheli alone. They fail to take into account the possible envi mental asbestos hazard of lnn- mhot Amnne asbr Journal ot the mi ruitunviM vuhi'w rv^ww* ASARCO ALV 0007497 workers, various studios have nil shown that the risk of dying of lung rancor is several times ftint 'if pleural and |>orilononl mesothelioma put together. In fine rnhorl Newhouse reported only 8 inesolheliomns ns rnmp.ired to n total of 36 cancers of the lung and pleura.1 Selikoff re ported 25 lung cancers in a cohort showing only 5 mesothe liomas2 and in two additional cohorts, hronchiogenic carci nomas were almost 3 times ns common ns pleural and peri toneal mesothelioma.' Admittedly, the high fretpieney of lung cancer in the general population makes it impossible to associate n given case with asbestos with the high degree of probability that exists for mesothelioma. Nevertheless, this is not adequate reason to disregard hronchiogenic car cinoma in my opinion. There is another different reason for including lung can cer data on the dose-response curve: This is that the meso thelioma frequency which the authors report is not propor tional to exposure. Indeed, the data they use show no change in the probability of contracting mesothelioma over on exposure range of three orders of magnitude. Thus, there seems to he no justification for drawing a mesothelio ma incidence envelope which hypothetically assumes a de creasing risk of mesothelioma with decreasing dose. Admit tedly this seems logical, hut there are no quantitative data to support it. In fact, investigators at Mount Sinai have found that workers exposed to high levels of asbestos are less likely to develop mesothelioma than those exposed to lower levels. This is because those in the high exposure group died of ashestosis before mesothelioma, which has a long latent period, had time In develop. Thus, among <589 workers who were traced fur 13 years, estimates of exposure vnried directly with ashestosis, but inversely with mesothe lioma.'1 If, however. Hrnckmnn and Kuhiiwhad lumped in the asbestos worker hronchiogenic carcinoma data with the mesothelioma data, both Knterline's'"' nod McDonald's' data support the concept of increasing cancer accompa nying increasing asbestos exposure. With the data present ed here, it seems unwarranted to extrapolate a standard which is several orders of magnitude below the lowest levels at which effects were seen using a slope which does not even approximate the data points. Furthermore, the as sumptions nu)de in developing the concent rut ion incidence envelope nre not elaborated, hut'do not appear to justify using the.minimuni expected risk of 150 mesotheliomas per year when the maximum number of mesothelioma deaths ex peeled per year would he 100.000 fatalities. When this same method of constructing a concentration-incidence en velope was applied by scientists at the Stale of Illinois in stitute for Knvironmental Quality.'1 they assumed a risk of cancer midway between the minimum ami maximum ex pected risks and based their recommended standard on this average expected risk, not on the minimum expected risk. Indeed, it is likely that the im idrnce of mesothelioma is under reported in the studies used fur drawing this curve, since most pathologists and phvsit iatis have never seen a mesothelioma. This should have led the authors to view the line predicting minima! probability of mi--otheliuma with suspicion, and to reject this line in favor of one predicting a higher probability of mesol helioma Furthermore, the minimum mid nuiviimint expected lines nre drawn through the points representing I he highest and lowest predicted exposure levels which resulted in mesothelioma. Hut there are only 12 points mi the graph, and since these nre highly variable, one would expect sta tistically that the addition of more points would lower the minimum and raise the maximum levels. Thus thev do not really reflect the smallest and largest possible probabilities of contracting cancer at all. since the data presented strongly suggest that additional data would widen the en velope. The authors state that occupational exposure cnneontrnlions must he modified to protect susceptible groups such as the elderly and infants, yet their extrapolation from oc cupational to environmental levels does not nreount for el derly and infants, hut instead assumes that the risk of de veloping mesothelioma is thp same for them as for workers except for the number of weekly hours of exposure. In actu ality. the risk of developing ranrer from nshestns is proba bly greater for infants if for no other reason than the fact that they may carry the inhaled irritant fibers-in their bod ies for a lifetime. The risk to the elderly is less than for workers, because the chance of their dying of other causes before the Intent period for mesothelioma has passed is greatly increased. I am glad the authors brought out clearly that the 0SHA asbestos standard is not stringent enough to protect work ers from contracting cancer. And I agree with their derision to assume that there is some risk of cancer at very low ex posure, levels, and to priueed to provide estimates of risk at these levels so that administrators, and the public as well, may choose a level of risk which seems, necessary in the light of competing demands. For example, we may wish temporarily to suffer a slightly increased risk of cancer from a hypothetical persistent substance which we cannot get out of the food chain overnight, rather than confiscate vast amounts of food with consequent malnutrition and skyrocketing food prices. The authors determined an ac ceptable risk for asbestos apparently based on general pub lic acceptance of a rate 10 times ns high as annual deaths due to transportation accidents. I believe that most people consider transportation essential. I gave an example of when it might he essential to eat enreinognns in food. As bestos may not he as essential as transportation. Some uses of it are not. If there nre adequate substitutes for a carcino gen which ran he used without intolerable economic penal ty. then I believe that no risk from exposure to that carcin ogen is acceptable. In other words, an administrator re quired to set a standard should he given several standards with the costs and benefits of each enumerated, and the po litical process will help him to make a wise decision. Hut to do such an analysis for asbestos will require a much more extensive data base than is presently available. The authors state that KFA's standards would permit 10 tons of asbestos to he emitted yearly in Connecticut, hut do not indicate the basis for deriving this estimate. This ap pears to assume that KPA standards will produce only 95% control, whereas large plants nre expected to use haghouses which give 99% control or better. The authors do a good job of extrapolating from their ambient standard to an emis sion standard, except for one serious omission. They fail to consider the likelihood of reentrainment of fibers hack into the air at a later time, or their ullimate.fatc, as for example, runoff into water and thus into the food chain. Nicholson has found that dust in attics of houses near a formerly ac tive asbestos plant are still rnntmuimifed with asbestos 20 years later.1 Danger has preliminary data which indicate in creasing asbestos in recent times in the Greenland ice cap.fl Thus the possibility of nrcurmilation of asbestos in the en vironment. with the possibility of Inter reentrainment into the air. must he home in mind. A more serious problem is the authors' assumption that there are KKItl nshestns fibers per naiingram of asbestos. Dr. Richard Thompson, whose estimate they quote, has in dicated that this estimate was an educated guess and now he believes that it is more likely that there are 100,000 or t .(KKi.ooti elect run microscopically visible nshestns fibers in a naiingram of asbestos.1,1 Nicholson has estimated that there is about I fiber fgreater than 5pm in length) per naiiogram of asbestos.' Hut. equivalents which apply to the workplace may not apply to ambient air, because (he larger filters settle out of the air first, leaving a larger proportion December 1975 Volume 25. No 1? 1213 ASARCO ALV 0007498 of small fibers. What ihis moans is I hat oven if everything else about the mesothelioma-asbestos exposure extrapola tion which the authors used wore reasonably correct-- which it probably is not --there may still be nn error of 10' or more due to the great inaccuracy which we incur when trying to convert filler counts to immigrants. Furthermore, ERA has repeatedly experienced a much poorer degree of replicability than the factor of 2 which the authors believe can be attained by present analytic capability. This is par ticularly true when, duplicate samples are sent to different experts. Testimony by Hr. Hrown al the federal court in St. I.ouis, which is reviewing the Reserve Mining Case, indicat ed much greater innrrurnry of the nnalytic methods used." The proposed asbestos sampling trnin is similar to that under test by KI'A. The authors do not describe the kind of filter they would use, hut membrane filters wotdd not be suitable at very high gas temperatures, or would require cooling the stack gases first. It is not obvious nor stated in the text as to why a condenser is recommended in the au thors' asbestos collect ion device. In conclusion, I would like to emphasize that I respect the authors' intention to make the best use of available data in trying to derive solutions to the environmental as bestos problem. I realize that the authors must have been aware of some of the criticisms that l have made, but prob ably felt that the need for [piaiifitative ambient air and emission standards warranted the proposal. However, my view is that the exposure level data from occupational studies, as well as present analytic methodology, arc so un reliable as to make the results of this exercise meaningless. I'nlil acceptable data are available, the most justifiable ap proach to protecting the public from asbestos health haz ards is (lie control of the major sources into the environ ment to the maximum extent practicable. Acknowledgment l)r. Irving .J. Kelikoff and Mr. -lames ('. Crowder. -Ir. pro vided valuable assistance in the preparation of this criti que. Addendum Following the writing of this review, it was pointc me that nil of the assumptions made by Hruckman hino are such as to make the sfnndnrd they recomm stringent. That is. their standard does not apper subject to the criticism that it may he ton strict, thing, it must be considered as loo weak. A review paper ronfirms this comment. Bruckmnn and Rubi cate that various sources exceed their standard paper ran lie considered a reasonable basis for requi bestos emissions to be less than the standard whi derive. While their standard cannot be considered t< equate!}* protective, it does seem reasonable to belii it should not be exceeded. References 1. M. L. Newhmise, "Asbestos in the work place and the nitWAmi (letup. Il\it Ifi:<17(I'lT.'tl. 2. I -I. Selifcnff. K. (\ Hamtnoml, mid .1. t'horg, "Cnrrin. ofanio-utcn-.hrstns."Ardt Enetrnn Health 2S:!8t(l 3. I. -/ Scliknff, K. C. Hammond, and H. Seidman, pres, the meeting of the Working Croup to Assess Biologies' ot Asbestos, 1.4RC. Lynn. France, October 4. 1972. 4. Private fommimiratinn with Dr. William .1. Nicholson. 5. P. K. Finlerlinr. P. rie t'mifle. nnd V. Henderson, "Mor relation to orrnpntional exposure in the asbestos indie ft. cop A/rd 14: H97 (1972). 6. P. K. Kntcrline. 1'. de Coufle. and V. Henderson, "Res; ennrer in relation to nrrnpntiminl exposures among ret bestos workers." Writ. J. Irtd Med. 30: Ifi2 (1973). 7. .1. ('. McDonald. "Cancer in Chrysolite Mines and paper 29 presented at Conferenee on Biological Effect iiestos, IARC. I.von, France. Octoher 2-S, 1972. 8. "Knvimomenta! Asbestos, Health Effects and Reromi Standards.'' Illinois Institute for Environmental Qual comber 1972 (available from Environmental Health H Center, P.O. Box fi99S. Chicago, II.I. St. Private communication with Dr. Arthur M. banger. Id, Private cnimmimcatioii with Dr. Richard J. Thompson 11. Reserve Mining Company, et al.. v. Hnitrd Slates of A et al. (Hnitrd States Court of Appeals. Eighth Circuit 4. 1974. p. 12. Authors' Response We are gratified to b-.iru ul the interest ill our article. The points which Dr. I'lumlee raise are certainly worthy of com ment. Dr. I'lumlre has correctly stated in the addendum to his review of the article that our objective was to derive a numerical asbestos standard which should not be exceeded at Ibis time. The criteria of mesothelioma was selected as the basis for developing the proposed ambient air quality asbestos stan dard of :I0 ng/m:', based on a .'to day average sample.'" be cause: I. As Dr. I'lumlee slated, the high frequency of lung cancer in the general population does make it difficult to relate it given case of bronchiogenir carcinoma to nsbest pnsure with the high degree of probability thatexi1 mesothelioma, and 2. Some investigators maintain that the smaller as fibers (those fibers less than S microns in lenglhl likely encountered in the ambient air (ns Dr. I'l has stated, the larger asbestos fibers settle out of t first, leaving a grenter proportion of small fibers) a cnpahle of producing lung cancer; however, it ha been demonstrated that these short asbestos fibe: incapable of indn*>ir ----- ASARCO ALV 0007499 Dr. Plumlee stntcs that mesothelioma frequency is nut proportional to exposure, however, investigations of the distribution or mesothelioma in occupationally exposed in dividuals indicate a definite correlation between exposure to asbestos fibers and mesothelioma incidence.'' " As was stated in the article, the boundaries of the asbes tos concentration-mesothelioma incidence envelope were based on the extreme high and low data points. Because quantitative low level exposure information is not currently available, the Illinois Knvironmcnt.il Health Resource Center (EHRC) decided to extrapolate the available occupa tional data by using a linear dose-effert relationship/' The authors agree with RHKC. Admittedly, more improved quantitative information roncerning the relationship be tween low level ambient asbestos fiber exposure and the as sociated health effects, especially the risk of contracting mesothelioma, is needed as soon ns possible to refine the asbestos exposure--mesothelioma inridenre envelope. The current EPA asbestos standard is essentially a no visible emission standard or the application of best avail able control technology. No visible emissions could easily he achieved by control equipment other than fabric filters which yield 95% control fo.g., wet cyclone). Plants whieh are currently meeting the no visible emissions standard without the use of fabric fillers cannot he expected to in stall fabric filters. Furthermore, best available control tech nology can menn different things to different people. Who is to decide what is ``best"? In our opinion, a numerical stnndnrd would he much easier to enforce, in addition to providing an incentive for manufacturers to develop more efficient control equipment, since some plants might not meet the proposed emission stnndnrd even with fabric fil ters. The reentrainment of asbestos fibers into the ambient nir at some later time, or their ultimate fate, was not con sidered when the emission standard was developed; how ever, the significance of this omission is unknown at this time. Dr. Plumlee seems to have rolifused asbestos fibrils (i.c.. ultimate asbestos fibers, 200 to 4(1(1 A in diameter arid often 2000 A or smaller in length) with asbestos fibers, which in general can either he less than or greater than n micron long, with varying diameter sizes Dr. Thompson estimated that there were approximately 100,000 to l.(X)0,000 asbes tos fibrils (not fibers) in a nanogram of asbestos.1" W'esolowski reported that there were approximately 0000 to 280,000 (arithmetic mean of 110,000) nsbostos fibrils per nanogrnm of asbestos.11 Dr. Thompson also estimated that there were 100 asbes tos fibrils per fiber visible under the electron microscope.111 Thus, assuming KM) fibrils per liber and 100,000 to 1,000.000 fibrils per nanogrnm. there would ho approxi mately 1000 to J0.000 asbestos fibers (not fibrils) per nanogram of asbestos. We used 1000 libers per nanogrnm in the development of our conversion Inetnr relating asbestos fi bers greater than f> microns in length In onnngrams of as bestos. Dr. Nicholson's estimate of 1 fiber greater than 5 microns in length per nonogram of asbestos appears to he consistent with nur assumption (i.c.. 20 asbestos fibers greater than 5 microns in length per nanogrnm of asbestos). Furthermore, on the basis of assuming that most ehrysotile asbestos fibers have n hollow cylindrical form with an aver age outer diameter 4 to 12 times the inner one, we calculate that there would he about 40 to f!.`> asbestos fibers 5 mi crons long, with a .`1:1 length to width ratio, per namigrain of ehrysotile asbestos.1* The Handle Columbus Laboratory reported that on the average {composite data from 88 am- rs. , __i. .. ti.t. phihole analyses) there were 26 amphihole asbestos fibers greater than 5 microns in length per nanogram of amphi hole asbestos.1''1 Thus, while the conversion used to relate asbestos fibers greater than 5 microns in length to nonograms of asbestos is not perfect, it seems-tn be reasonably accurate (20 vs. 26) and would certainly not introduce er rors of 1000 or more into our asbestos exposure-mesotheli oma inridenre envelope as Dr. Plumlee claims. The accuracy of the measurement technique used by Hattelle to determine the ehrysotile asbestos concentration of nmbiont air samples was reported to be 50%.based on the analyses of activated ehrysotile sample.1'' However, Dr. Plumlee's point concerning the problem of measuring the asbestos content of environmental samples is well taken. The accuracy of the techniques used to sample for asbestos and the analytical procedures used for the identification and counting of asbestos fibers should be improved and standardized as soon ns possible. In conclusion, we feel that our study provides a reason able basis for requiring asbestos emissions to he less than our proposed standard, the implementation of which on a national basis would result in both significant reductions in asbestos emissions and projected asbestos related fatalities as compared to the current EPA no visible emissions stan dard. References 1. Knvirimnicnt.il Health Resource Center News, Illinois Insti tute for Knvirnnment.il Quality. Chicago, Jl,, Issue # 12. 1974. 2. I*, dross. "Is short-filtered asbestos dust a biological hazard," Arrh Environ. Ilrallh 29,1 IS (1974). it. Ilrallh Hffr.li and llrromnicndatinw far Atmniphrrie Lend, Cadmium. Mrrrurv and Asbestos. Environmental Health Re sources Center. State of Illinois Institute for Environmental Quality, Report ff II K().7;i-2. Chicago. II.. 11174. 4. -I. K. Know. S. Holmes. R. Doll, and I. I). Hill. "Mortality from lung runi'er mul oilier causes among workers in nn nsbrsto* textile factory," 'Iru ./ hid Mrd. 2.7: 294 (I96K). 5. II C. I.ewinsohn. "The medirat surveillance of ashestos work, ers." Km. Sol Ilrallh ./ 92:69(19721. li. M 1.. New house. "A study of the mortality of workers in an asficstns laetory.'' lirit hid Med 26: 2!M (1969). 7. M I.. New house. (! Kerry. .1. C. Wagner, and N. E. Turok, "A study of the mortality of female asbestos workers." Brit. J. Ind Med 29: 121 (1972). H. I. 4. Selikoff. .1 Chure. and K. (\ Hammond. "As-bestos expo sure anil nroplnsia Am Mrd. Anar.. I MS: 22 (1964). 9. 4. Slumphiiis. "Epidemiology of mesothelioma on Walcheren Island." /)n/. ././ad Med 2K: C>9 (I97IK )0. It. 4. Thompson, personal communication. May 7.197S. It. 4. 4. Wesolewski. "Asbestos in the California Environment." Air and Industrial Hygiene Laboratory Report. AIHI. if 164, California Stale Department nf Health, llerkelev. California, M.iv. 1974. 12. "Asbestos in llm drent Lukes ttasiu with Emphasis on Luke Superior." A Report to the International Joint Commission trom the dreat Lakes Research Advisory Hoard. February, 197.7. 19. f. W. Mellon, personal ronunmu'eatiim, February tit, f97fi. Mr Rriiekinan is principal air pollution rontrol engineer mul Mr. liiihino is assistant director of the Air Compliance t'nil. Engineering Section. Connecticut Department of En vironmental I'rotection. State Office Huilding. Hartford, (*T ndl In. This paper was presented as Paper No. 74-222 at the Ii7ih Annual Meeting of APCA at Denver in .lunc 1974. I)r. Plumlee. whose discussion of the pnper is also presented here, is a medical science adviser with the U. S. Environ mental Protection Agency. ASARCO ALV 0007500