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FILE NAME Rogers Corporation ROG DATE 1975 DOC ROG061 DOCUMENT DESCRIPTION Journal Article - Asbestos Rationale Behind a Proposed Air Quality Standard This article was downloaded by 50.169.118.55 On 13 August 2014 At 08:55 Publisher Taylor & Francis Informa Ltd Registered in England and Wales Registered Number 1072954 Registered office Mortimer -~ House 37-41 Mortimer Street London W1T 3JH UK Air & Waste Management Association Association Journal of the Air Pollution Control Association Publication details including instructions for authors and subscription information http://www.tandfonline.com/loi/uawm16 http://www.tandfonline.com/loi/uawm16 Asbestos Rationale Behind A Proposed Air Quality Standard a a Leonard Bruckman & Robert A. Rubino a Connecticut Department of Environmental Protection Published online 13 Mar 2012 To cite this article Leonard Bruckman & Robert A. Rubino 1975 Asbestos Rationale Behind A Proposed Air Quality Standard Journal of the Air Pollution Control Association 25:12 1207-1215 DOI 00022470.1975.10470197 To link to this article http://dx.doi.org/10.1080/00022470.1975.10470197 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information the Content contained in the publications on our platform However Taylor & Francis our agents and our licensors make no representations or warranties whatsoever as to the accuracy completeness or suitability for any purpose of the Content Any opinions and views expressed in this publication are the opinions and views of the authors and are not the views of or endorsed by Taylor & Francis The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information Taylor and Francis shall not be liable for any losses actions claims proceedings demands costs expenses damages and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with in relation to or arising out of the use of the Content This article may be used for research teaching and private study purposes Any substantial or systematic reproduction redistribution reselling loan licensing systematic supply or distribution in any form to anyone is expressly forbidden Terms & Conditions of access and use can be found at http www.tandfonline.com/page/terms-and-conditions asbestos rationale behind a proposed air quality standard 2014 August 13 08:5 at ( 50.169 by Downlade Leonard Bruckman and Robert A. Rubino Connecticut Department of Environmental Protection The following discussion presents a proposed asbestos air quality standard and the rationale utilized in its formulation The criterion of mesothelioma has been selected as the basis for developing the subject standard A concentration mesothelioma incidence envelope has been constructed for the general population based on mesothelioma incidence due to industrial exposure An ambient air quality asbestos standard of 30 nanograms per cubic meter based on a day average sample is recommended This standard is projected to result in 150 nationwide fatali- ties Available ambient air asbestos data indicates that urban and remote urban areas have as- bestos levels typically less than 1 nanogram per cubic meter while urban areas are usually below 30 nano- grams per cubic meter Dispersion calculations are used to determine the maximum allowable asbestos mass emission standard for manufacturing sources 24 grams per day and a maximum allowable average asbestos concentration 25 micrograms per cubic meter A family of curves for various workdays depicting the average allowable asbestos concentration as a function of total asbestos contaminated exhaust gas flow rate consistent with the 24 grams per day emission standard are present- December 1975 Volume 25 No. 12 ed In addition a preliminary asbestos stack sampling train has been developed requiring electron microscopy as the analytical procedure to be used to determine the sample asbestos content The implementation of the proposed emission standard will lower the expected annual asbestos emissions from manufacturing operations in Connecticut to below one ton compared to the 10 tons emitted if the Federal EPA asbestos regulation is accepted The proposed air quality standard will fur- ther reduce Connecticut asbestos fatalities to only two persons annually Asbestos the generic name given to a variety of fibrous silicate naturally occurring minerals is present as an invisible and anonymous ingredient in a myraid of industrial products such as paint floor tiles gaskets cement shingles pipes brake linings fireproofing and insulating materials and asbestos fabrics The principal variety of asbestos used in industry is chrysotile greater than 95 with amosite and crocidolite being of lesser significance Consumption of asbestos in the U. S. has risen from approximately 40,000 tons in 1905 to nearly 800,000 tons in the early 1970's about a fold increase 1207 2014 August 13 08:5 at 5 50.169.1 by Downlade Health Occupational It has been well known for nearly half a century that some persons subjected to asbestos dust during work devel- disease oped a severely crippling and sometimes fatal lung called asbestosis Asbestosis can be classified as an occupational disease which occurs after relatively heavy exposure to asbestos fiber dust The use of antibiotics in the 1930'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 asbestosis began living long enough to develop asbestos cancer of the lung gastrointestinal tract stomach and especially the lining of the stomach and lung i.e. mesothelioma Asbestos has become one of the largest industrial causes of cancer in the world.5 All the commercially used forms of asbestos can produce asbestosis as well as the types of cancer previously mentioned Mesothelioma was regarded by pathologists until recently as an extremely rare disease and at times a medical curiosity In 1965 Dr. Selikoff and his associates conclusively proved a causal link between asbestos fiber exposure and mesothelioma.6,7 A significant and somewhat frightening feature of mesothelioma is the extended lag period between first exposure to asbestos fibers and the first symptoms of this form of cancer It has been reported in the literature that this time period may be anywhere from 20 to 40 years 10 This long time interval emphasizes the latent insidious problem asbestos fiber exposure continually creates for individuals both occupationally and occupationally exposed Health Occupational 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 asbestos was mined and milled and containing products manufactured pathologic alterations i.e. pleural cal- cification were discovered in populations with no history of occupational exposure Recent studies have indicated that urban dwellers harbor high quantities of asbestos fibers in their lungs.3,8,16 18 The most serious implication of the hazards of occupational 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 popula- tion.3,6,19,20 Current cases of mesothelioma must be associated with asbestos fiber inhalation that took place 20 30 or more years ago when world consumption of asbestos was only about 500,000 year and that neoplasms associ- ated with today's annual production of over 4,000,000 tons that will not be evident until the 1990s The health hazard asbestos fiber exposure poses to the general public is compounded by the synergistic effect of tobacco smoke and possibly other air pollutants such as pyrene. ,, Relationship between Occupational Asbestos Exposure and Incidence of Mesothelioma The Federal EPA has recognized the need to control the emission of asbestos fibers into the ambient air and has recently promulgated National Emission Standards for Hazardous Air Pollutants Asbestos Beryllium and Mercu- ry Alternatives to the EPA's required control strategies are conceivable and the following discussion presents one such option the formulation of an asbestos ambient air quality standard and a compatible mass emission standard for manufacturing sources of asbestos emissions The probability of a person in the general community contracting mesothelioma has been chosen as the basis for developing the asbestos air quality standard Most of the information presently available on exposure to asbestos has been collected in industrial environments Studies present- ly available on mesothelioma incidences due to industrial exposure do not report the fiber concentration to which affected workers were exposed however a study by the National Institute for Occupational Safety and Health NIOSH reports short term fiber concentrations for a number of industrial settings While these short term fiber concentrations are of recent origin and as such are not directly related to the epidemiological studies of mesothelioma incidence they do reflect the difference between well and poorly controlled processes and thus can be used as an estimate of low or severe exposure Table I summarizes mesothelioma incidence data from several different studies along with high and low concentrations from the NIOSH document for shipyards textile processes construction operations and insulation plants These data were used to construct a concentration incidence envelope depicted in Figure 1 Relationship between Fibers Greater than Five Microns to Nanograms of Asbestos Asbestos fibers monitored in industrial settings greater than 5 ...min length length to width ratio of greater than 3 using phase contact PC light microscopy 430x magnifi- cation account for approximately % of all asbestos fibers present by number Hence in the occupational environment every asbestos fiber greater than 5 ...min length corresponds to an actual fiber count of 50 i.e. 0.02 = 50 1208 Table I. Incidence of mesothelioma and asbestos concentrations in occupational environments Industry Cohort Number of individuals Mesothelioma incidence % Reference Highest Lowest average concen- average concen- tration tration fiber fiber 7 cm cm cm cm Insulations plants Shipyards 689 3000 2.18 0.73 23 23 26 74.4 0.1 8.7 0.3 Construction Textile plants 632 716 0.63 1.50 23 29 23 25 7.1 29.9 0.9 0.1 1300 1.00 23 25 30 29.9 0.1 1300 1.20 23 24 31 29.9 0.1 a Most of the individuals in these studies had been followed for 20 b Concentrations from NIOSH document. years or longer Journal of the Air Pollution Control Association 2014 August 13 08:5 at 5 $ 50.169 by Downlade 10 107 m m ) 5 > Fibers 10+ L 106 105 105 m Nanograms Nanograms 7104 Nanograms Nanograms Nanograms 103 . 10 1 i de 110 1 10-6 10-5 10-4 10-2 10-1 Hypothetical probability of contracting mesothelioma Figure 1. Expected incidence of contracting mesothelioma as a function of Industrial air asbestos exposure hr day 5 day week Ambient Air Asbestos Standard Now that a set of curves relating the nationwide ed cases of mesothelioma as a function of ambienteaxiprecats-bestos expsoure has been constructed a desired ambient air asbestos level can be 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 smallest possible probability of contracting cancer of the . mesothelioma incidence curve was used An num- ambient air asbestos standard of 30 m was chosen This level should result in about 1/10 the total nationwide ber of fatalities approximately 150 from airplane accidents and approximately the same number of deaths as from train mishaps the maximum line or greatest probability line would have yielded over 100,000 expected fatali- ties The use of the minimum line instead of an average line was chosen as 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 envelope Dr. Thompson personal communication reported that there are about 1000 total asbestos fibers per nanogram of asbestos Therefore 20 asbestos fibers greater than 5 m long have been assumed equivalent to one nanogram of asbestos i.e. 1000/50 = 20 This appears to be a reasonable assumption since Lynch and his workers reported based on magnesium determinations that for certain manufac- turing operations one ng of asbestos was equivalent to 6.7 22.5 to PC.27 fibers greater than 5 ...mlong as determined by Relationship between Occupational Asbestos Exposure and Incidence of Mesothelioma The mesothelioma incidence envelope depicted in Figure 1 appears as a function of both fibers greater than 5 min length and ng of asbestos respectively Occupational exposure concentrations which are based 8 on an hr day 5 day week must now be related to exposure levels for the general public 24 hr day 7 day week which contains many susceptible groups such as the elderly and infants who must voluntarily and continuously endure the ambient environment This can be accomplished by dividing the occupational exposure levels by 4.2 24 hr hr x 7 days days 4.2 A mesothelioma incidence envelope for ambient air asbestos exposure for the general public has thus been constructed as shown in Fig- ure 2 Ambient Air Asbestos Levels How reasonable is the desired ambient air standard of 30 ng of asbestos Nonurban and remote nonurban air- borne asbestos concentrations are typically less than 1 ng n.28 Urban areas usually have asbestos concentrations below the desired 30 m standard except in heavily industrialized areas e.g. Manhattan N.Y.C. and Philadelphia around construction sites and toll booths 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 ...min length or cm^ 106 cm^ 20f = 105 m is designed specifically to protect the workman from contracting asbestosis which results from heavy occupational exposure to asbestos This standard does not take into account the effect of asbestos as a carcinogenic agent The OSHA standard is equivalent to a general public exposure of 25,000 ng of asbestos mi.e. 105 = 25,000 It is concluded that the proposed standard of 30 m is not unreasonable even though it is approximately 1/1000 of the OSHA standard since the latter standard is not nearly stringent enough to protect workmen from contracting cancer - m m ng ng 10 r concentration concentration 7. concentrationconcentration concentration Proposed 10 }standard- e ov standard- concentration concentration 30 a , manny asbestos ol asbestos 10 re 1 asbestos y! ! air , air y ' Ambient 10 Ambient 101 Ambient ra | 1 102 103 150 Nationwide expected Min Min , 24 104 cases of p an v7 a 4 1 -Max , 105 106 mesothelioma Figure 2. Nationwide expected cases of mesothelioma as a function of ambient air asbestos exposure assumed popula- tion of United States was 230 million people December 1975 Volume 25 No. 12 Asbestos Emission Standard Figure 3 depicts the maximum allowable emission rate consistent with the desired 30 m ambient air standard based on both a 24 hr average and 30 day average sample at corresponding distances from a source These emission rate curves were constructed using dispersion estimates and local Connecticut meteorological assumptions Thus the maximum allowable emission rate consistent with the aforementioned assumptions would be either 20 or 24 day respectively at a distance of approximately either 300 or 350 ft from the source A 24 hour sampling period is not really long enough to reflect properly the average ' ambient asbestos levels in any region and is very sensitive to short term asbestos emissions An ambient air standard based on a 30 day average sampling period is more manageable from a 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 2014 August 13 08:5 at 50.169.15 50.169.15 by Downlade 103 103 day day grams grams grams emissionsemissions emissions 102 asbestos asbestosasbestos Allowable Allowable Alowable Allowable oe - ae fa vy 101 1 102 10 104 Distance from source feet Figure 3. Calculated maximum allowable asbestos emission rate as a function of distance from source assumed 4 sec wind speed 10m effective stack height 40 frequency factor for wind direction and C stability class asbestos standard should be based on a 30 day average sample and the corresponding maximum allowable asbestos emission rate is 24 day The aforementioned emission and ambient air quality standards result in a maximum daily inhaled asbestos dosage of 600 ng 20 day total average adult daily respiratory air intake ^ 30 m = 600 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 m A person walking through the plume will then experience an asbestos concentration for a 15 minute time period equivalent to 10 times his maximum allowable daily dos- age Figure 4 depicts the average allowable asbestos concen- tration as a function of contaminated exhaust gas flow rate for various periods of daily plant operation consistent with a maximum allowable emission rate of 24 day and the desired air quality standard This Figure could be utilized as an emission standard of sorts the larger the ascontaminated gas flow rate the lower will be the allowable average asbestos plume concentration Manufacturing Sources of Asbestos Emissions A survey of asbestos users in Connecticut summarized in Table II indicates that annual state uncontrolled asbestos emissions could amount to almost 200 tons Comments solicited from manufacturers of particulate control equipment in addition to other reports indicate that there should be no problem in obtaining at least a 95 asbestos emission control efficiency using either a high energy a scrubber or fabric filter and in many instances control ef- ficiencies as high as 99.9 are attainable It should be understood 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 Notwithstanding the employment of best available asbestos control technologies as required by the Federal EPA asbestos regulation almost 10 tons of as- bestos might be emitted into the Connecticut atmosphere each year as a result of manufacturing operations In order to evaluate properly the potential hazard of this airborne 1210 asbestos it is important to understand that 1 g of asbestos could contain up to 1,000,000,000 asbestos fibers and one inhaled asbestos fiber could potentiate a cancer The implementation of the proposed 24 day emission standard in Connecticut would lower the expected annual asbestos emissions from manufacturing operations to below 1 ton and thereby provide the impetus for the development of improved asbestos air pollution control equipment In addition greater than 95 of the sources should have no problem meeting the proposed emission standard employing state control technology Brake Lining Decomposition Asbestos as a result of brake lining decomposition might contribute another 1.5 tons of airborne asbestos fibers into the Connecticut atmosphere each 3,39-42 Several investigators have suggested that the asbestos emitted as a re- sult of brake usage is not a significant source of atmospher- ic asbestos however in New York City air asbestos concentrations contiguous to a toll booth were to 5 times background levels Additional data are needed before the impact of brake lining decomposition on airborne asbestos levels can be ascertained Demolition The demolition of asbestos sprayed highrise buildings could result in the emanation of a large amount of asbestos fiber dust unless adequate precautions are taken If the asbestos emissions caused by demolition operations could be accurately accounted for the actual annual tonnage of asbestos emitted into the Connecticut atmosphere might be significantly increased Asbestos Stack Sampling Train It has been suggested that an asbestos air quality regulation which employs an emission standard will suffer from the unavailability of an adequate stack sampling procedure however other investigators report that there should be no problems either theoretical or physical in stack sampling for asbestos than there would be in sampling any complex source The stack sampling train depicted in Figure 5 a modified version of the approved federal partic- ulate train might be used to measure asbestos stack emis- sions however this proposed train has never been field tested cfm rate flow hr day gas contamied 105 105 105 Y asbetos 104 T 104 104 rT Total 1010 10,, : 102 103 104 10.5 Average asbestos concentration m Figure 4. Total asbestos contaminated gas flow rate as a function of allowable asbestos air concentration Journal of the Air Pollution Control Association Table II A survey of asbestos users in Connecticut 1972 ~ Type of source Asbestos cement floor tile and paper mfg Friction product mfg Textile mfg Miscellaneous mfg . Vehicle brake lining & clutch facing erosion Demolition operations Number of sources 17 4 12 10 1.56 X 106 2500 W. E. Davis & Assoc b Jacko et al Asbestos used tons 600 3200 400 900 A Uncontrolled a emission factor ton 4 - 120 40 10 30 mileb Unknown Unknown Potential uncontrolled emissions year 1.2 192 0.8 4.5 1.5 Unknown 2014 August 13 08:5 at .55 .55 50.169.1 by Downlade Analytical Asbestos Determination In the last few years techniques for determining chrysotile asbestos concentrations in terms of m in the ambient air based on electron microscopy have been developed and used with a reasonable degree of suc- Probe PARTICULATE COLLECTION DEVICE Stack wall Water jacket Heated area Heated Filter holder Hot water out- Reverse pitot tube Pitot manometer 200 F Water heater 200 F Hot water in Pump Flexible tubing CONDENSER Thermometer Check valve -Ice -Ice bath 28,33,38,41,44 Dr. Selikoff 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 calibrations 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 2.16,33 This technique should be more than adequate in determining 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 asbestos 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 mesothelioma 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 Compliance Unit Hartford CT Dr. Robert S. Pogrund Environmental Health Resource Center Illinois Institute for Environmental Quality Chicago IL Dr. Richard J. Thompson Chief Analytical Chemistry Branch U.S. Environmental Protection Agency gave valued assistance Flexible tubing _____CONTROL MODULE Dry test meter Figure 5. Proposed asbestos sampling train References 1. R. A. Clifton personal communication U. S. Bureau of Mines February 1 1973 2. R. J. Sullivan and Y. C. Athanassidas Air Pollution Aspects of Asbestos U. S. Department of Commerce National Technical Information Service NTIS #PB 188 080 1969 3. Asbestos Need for and Feasibility of Air Pollution Controls Committee on Biologic Effects of Atmospheric Pollutants Division of Medical Sciences National Research Council National Academy of Sciences Washington D. C. 1971 4. I. J. Selikoff ~ Hammond and J. Churg Carcinogenicity of amosite asbestos Arch Environ Health 25 183 1972 5. K. R. Boucot W. Weiss H. Seidman W. K. Carnahan and D. A. Cooper The Philadelphia Pulmonary Neoplasm Research Project basic risk factors of lung cancer in older men Am J. Epidemiol 95 4 1972 December 1975 Volume 25 No. 12 1211 2014 August 13 08:5 at 5 50.169.1 by Downlade 6. I. J. Selikoff J. Churg and E. C. Hammond Relation beMtweeden2e7x2po5s6u0r1e 9o6f 0asbestos and mesothelioma New Eng J. Times 7. R. Sherrill Asbestos the saver of lives has a deadly side N. Magazine Section pp 12 1358 64January 21 Group 8. Hazards of Asbestos to Human Health Minnesota Public Re- search Interest Minneapolis MN 1972 9. I. J. Selikoff and E. C. Hammond Environmental epidemiol- ogy III Community effects of occupational environmen- tal asbestos exposure Amer J. Publ Health 59 1658 1968 10.J. C.C. Wagner Epidemiology of diffuse mesothelial tumors evidence of an association from studies in South Africa and the United Kingdom Ann N. Y. Acad Sci 132 575 1965 11. T. Ashcroft and A. G. Heppleston Mesothelioma and Asbes- tos on Tyneside A Pathological Social Study in Pneumocon- iosis Proceedings of the International Conference Johannes- burg H. A. Shapiro ed Oxford University Press Cape Town South Africa 1970 12. J. Hromek The mean incidence of characteristic pleural changes in citizens of the western part of former Jilalara Region Rozhl Tuberk 22 405 1962 13. R. Kiviluoto Pleural calcification as a roentgenologic sign of occupational Endemic Anthophyllite Acta Radiol Suppl 194 1 1960 14 L. O. O.. MeurmanMeurman Asbestos bodies and pleural plaques in a Finnish series of autopsy cases Acta Path Microbiol Scan Suppl 181 1 1966 pollution 15. V.V. Raunio Occurrence of unusual pleural calcification in Fin- land Ann Med Inf Fenn Suppl 49 55 1966 16. A. M. Langer and I. J. Selikoff Chrysotile Asbestos in Lungs of Residents of New York City in Proceedings of the Second International Clean Air Congress H. M. Englund and W. T. Beery eds Academic Press NY 1971. pp 161 165 17. I. J. Selikoff W. J. Nicholson and A. M. Langer Langer Asbestos air Arch Environ Health 25 1972 . 18. M. D. Utidjiam P. Gross and R. T. P. deTreville Ferruginous AbordcihesEnivnirhounmaHenalltuhng1s7 p3r2e7va1l9en6c8e at random autopsies 19. J. Lieben and H. Pistawka Mesothelioma and asbestos expo- sure Arch Environ Health 14 559 ( 1967 20. M. L. Newhouse and H. Thompson Mesothelioma of pleura and peritoneum following exposure to asbestos in the London area Brit J. Ind Med 22 261 1965 21. EPA sets final emission standards for asbestos beryllium and mercury J. Air Poll Control Assoc 23 398 1973 and Fed- eral Register 38 April 6 1973 22. Criteria for a Recommended Standard for Occupational Ex- posure to Asbestos U. S. Department of Health Education and Welfare Public Health Service Health Services and Men- tal Health Administration National Institute for Occupational Safety and Health HSM 72-10267 Washington DC 1973 Health 23. Effects and Recommendations for Atmospheric Lead Cadmium Mercury and Asbestos Environmental Health State Resources Center of Illinois Institute for Environmental Quality Report #II #II 73-2 Chicago IL 1973 24. H. C. Lewinsohn The medical surveillance of asbestos work- ers Roy Soc Health J. 92 69 717972 25. M. L. Newhouse G. Berry J. C. Wagner and N. E. Turok A study of the mortality of female asbestos workers Brit J. Ind Med 29 134 1972 26. J. Stumphuis Epidemiology of mesothelioma on Walcheren Island Brit J. Ind Med 28 1971 27. J. R. Lynch H. E. Ayer and D. L. Johnson The interrela- tionships of selected asbestos exposure indices Amer Ind Hyg J. 31 598 1970 : personal 28R..J.J. Thompson Thompson and G. Ambient Air May communication preprint R. J. B. Morgan Determination of Asbestos in 2 1973 J. 29. I. J. Selikoff Churg Churg and E. C. Hammond Asbestos expo- sure and neoplasia J. Am Med Assoc 188 22 1964 30. M.M. L. Newhouse A study of the mortality of workers in an bestos factory Brit J. Ind Med 26 294 1969 as- 31. J. F. Knox S. Holmes R. Doll and I. D. Hill Mortality from lung cancer and other causes among workers in an asbestos textile factory Brit J. Ind Med 25 293 1968 32. W. Fulkerson and W. E. Goeller eds Cadmium The Dissi- pated Element Oak Ridge National Laboratory Report ORNL Oak Ridge TE 1973 33. Measurement of Asbestos in Ambient Air Final Report Contract 70-92 U. S. Environmental Protection Agen- cy Research Triangle Park NC 1970 34. Background Information on Development of National Emis- sion Standards for Hazardous Air Pollutants Asbestos Beryl- lium and Office of Mercury U. S. Environmental Protection Agency Air and Water Office of Air Quality Plan- ning and Programs Standards APTD Research Triangle Park Atmospheric 35. D. B. Turner Workbook of Dispersion Esti- mates U. S. Environmental Protection Agency Office of Air Programs Research Triangle Park NC 1970 Conecticut 36. G. cal Wight personal communication Connecticut meteorologi- data Connecticut Department of Environmental Protec- tion 1973 37. Control Techniques for Asbestos Air Pollutants U. Envi- ronmental Protection Agency Office of Air and Water Pro- RgersaemasrcOhffTircieanogflAeiPraQruakliNtyC P1l9a7n3ning and Standards 117 38. C. F. Harwood Asbestos Air Pollution Control State of Illinois Institute for Environmental Quality IIEQ Document 71-8 Chicago IL 1971 " 39. National Inventory of Sources of and Emissions Asbestos Section III W. E. Davis and Associates National Air Pollu- tion Control Administration contract # 22-69-131 PB 192- 252 Leawood KS 1970 40. M. G. Jacko R. T. DuCharme and J. H. Somers How much asbestos do vehicles emit Auto Eng 81 38 1973 41. M. G. Jacko and R. T. DuCharme Brake Emissions Emission Measurements From Brake and Clutch Linings from Selected Mobile Sources Bendix Research Laboratories U. S. Environ- mentalProtection Agency report # 68-04-0020 Southfield 42. J. R. Lynch Brake lining decomposition products J. Air Poll Control Assoc 18 824 1968 Automobile 43. A. E. Anderson R. L. Gealer R. C. McCune and J. W. Sprys Asbestos Emissions from Brake Dynamometer Tests Paper 730549 presented at SAE Engineering Meeting Detroit MI 1973 , personal 44. W. J. Nicholson A. N. Rohl and E. F. Ferrand Asbestos Air Pollution in New York City in Proceedings of the Second In- ternational Clean Air Congress H. M. Englund and W. T. Beery eds Academic Press New York 1971. pp 136-139 45. W.W. S. Smith communication Entropy Environmen- talists Inc. July 23 1973 Discussion Lawrence A. Plumlee M.D. U. S. Environmental Protection Agency Medical Science Adviser It is always easy to find fault with another person's work and it is difficult to come up with alternatives which can- not be criticized with just as much justification Those of us associated with preparing the standards and regulations for environmental protection are often faced with the necessity of doing the best we can with a limited amount of information This is particularly true when there is evidence that 1212 damage to the public health will result if we fail to act Nevertheless it is my contention that Messrs Bruckman and Rubino have made some maneuvers which render their asbestos standards unsupportable One of these is their de- cision to base their standards on the risk of mesothelioma alone They fail to take into account the possible environmental asbestos hazard of lung cancer Among asbestos Journal of the Air Pollution Control Association 2014 August 13 08:5 at 5 50.169 by Downlade workers various studies have all shown that the risk of dying of lung cancer is several times that of pleural and peritoneal mesothelioma put together In one cohort Newhouse reported only 8 mesotheliomas as compared to a total of 36 cancers of the lung and pleura.,, Selikoff re- ported 25 lung cancers in a cohort showing only 5 mesotheliomasand in two additional cohorts bronchiogenic carcinomas were almost 3 times as common as pleural and peritoneal mesothelioma.Admittedly the high frequency of lung cancer in the general population makes it impossible to associate a given case with asbestos with the high degree of probability that exists for mesothelioma Nevertheless this is not adequate reason to disregard bronchiogenic car- cinoma in my opinion . There is another different reason for including lung cancer data on the response curve This is that the meso- thelioma frequency which the authors report is not proportional to exposure Indeed the data they use show no change in the probability of contracting mesothelioma over an exposure range of three orders of magnitude Thus there seems to be no justification for drawing a mesothelioma incidence envelope which hypothetically assumes a decreasing risk of mesothelioma with decreasing dose Admittedly this seems logical but 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 asbestosis before mesothelioma which has a long latent period had time to develop Thus among 689 workers who were traced for 13 years estimates of exposure varied directly with asbestosis but inversely with mesothelioma If however Bruckman and Rubino had lumped in the asbestos worker bronchiogenic carcinoma data with the mesothelioma data both Enterline's and 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 magnitude below the lowest levels at which effects were seen using a slope which does not even approximate the data points Furthermore the assumptions made in developing the concentration envelope are not elaborated but do not appear to justify using the minimum expected risk of 150 mesotheliomas per year when the maximum number of mesothelioma deaths expected per year would be 100,000 fatalities When this same method of constructing a concentration en- velope was applied by scientists at the State of Illinois In- a stitute for Environmental Quality they assumed risk of cancer midway between the minimum and 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 incidence of mesothelioma is under reported in the studies used for drawing this curve since most pathologists and physicians have never seen a mesothelioma This should have led the authors to view the line predicting minimal probability of mesothelioma with suspicion and to reject this line in favor of one predicting a higher probability of mesothelioma Furthermore the minimum and maximum expected lines are drawn through the points representing the highest and lowest predicted exposure levels which resulted in mesothelioma But there are only 12 points on the graph and since these are highly variable one would expect statistically that the addition of more points would lower the minimum and raise the maximum levels Thus they 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 concentrations must be modified to protect susceptible groups such as the elderly and infants yet their extrapolation from occupational to environmental levels does not account for elderly and infants but instead assumes that the risk of de- veloping mesothelioma is the same for them as for workers except for the number of weekly hours of exposurIen actuality the risk of developing cancer from asbestos is probably 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 latent period for mesothelioma has passed is greatly increased I am glad the authors brought out clearly that the OSHA asbestos standard is not stringent enough to protect workers from contracting cancer And I agree with their decision to assume that there is some risk of cancer at very low ex- posure levels and to proceed 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 public acceptance of a rate 10 times as high as annual deaths due to transportation accidents I believe that most people consider transportation essential I gave an example of when it might be essential to eat carcinogens in food Asbestos may not be as essential as transportation Some uses carcino- of it are not If there are adequate substitutes for a gen which can be used without intolerable economic penalty then I believe that no risk from exposure to that carcinogen is acceptable In other words an administrator re- quired to set a standard should be given several standards with the costs and benefits of each enumerated and the political process will help him to make a wise decision But to do such an analysis for asbestos will require a much more extensive data base than is presently available The authors state that EPA's standards would permit 10 tons of asbestos to be emitted yearly in Connecticut but do not indicate the basis for deriving this estimate This ap- pears to assume that EPA standards will produce only 95 control whereas large plants are expected to use baghouses which give 99 control or better The authors do a good job of extrapolating from their ambient standard to an emis- si^nstandard except for one serious omission They fail to consider the likelihood of reentrainment of fibers back into the air at a later time or their ultimate fate as for example runoff into water and thus into the food chain Nicholson has found that dust in attics of houses near a formerly active asbestos plant are still contaminated with asbestos 20 years later.4 Langer has preliminary data which indicate in- creasing asbestos in recent times in the Greenland ice cap. ,, Thus the possibility of accumulation of asbestos in the en- vironment with the possibility of later reentrainment into the air must be borne in mind A more serious problem is the authors assumption that there are 1000 asbestos fibers per nanogram 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 1,000,000 electron microscopically visible asbestos fibers in a nanogram of asbestos.10 Nicholson has estimated that there is about 1 fiber greater than 5...min length per nanogram of asbestos.4 But equivalents which apply to the workplace may not apply to ambient air because the larger fibers settle out of the air first leaving a larger proportion December 1975 Volume 25 No. 12 1213 2014 August 13 08:5 at 35 50.169.1 by Downlade of small fibers What this means is that even if else about the mesothelioma everything exposure extrapola- tion which the authors used were reasonably correct- which it probably is there may still be an error of 103 or more due to the great inaccuracy which we incur when trying to convert fiber counts to nanograms Furthermore EPA 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 particularly true when duplicate samples are sent to different experts Testimony by Dr. Brown at the federal court in St. Louis which is reviewing the Reserve Mining Case indicated much greater inaccuracy of the analytic methods used.11 The proposed asbestos sampling train is similar to that under test by EPA The authors do not describe the kind of filter they would use but membrane filters would 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 collection 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 asbestos problem I realize that the authors must have been aware of some of the criticisms that I have made but probably felt that the need for quantitative 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 are so un- reliable as to make the results of this exercise meaningless Until acceptable data are available the most justifiable ap- proach to protecting the public from asbestos health haz- ards is the control of the major sources into the environ- ment to the maximum extent practicable Acknowledgment Dr. Irving J. Selikoff and Mr. James U. Crowder Jr. provided valuable assistance in the preparation of this criti- que Addendum Following the writing of this review it was pointed out to me that all of the assumptions made by Bruckman and Rubino are such as to make the standard they recommend less this stringent That is their standard does not appear to be subject to the criticism that it may be too strict If any- thing it must be considered as too weak A review of paper confirms this comment Bruckman and Rubino indicate that various sources exceed their standard Their paper can be considered a reasonable basis for requiring asbestos emissions to be less than the standard which they derive While their standard cannot be considered to be adequately protective it does seem reasonable to believe that . it should not be exceeded References 1. M. L. Newhouse Asbestos in the work place and the commu- nity Ann Occup Hyg 16:97 1973 2. I. J. Selikoff E. C. Hammond and J. Churg Carcinogenicity of amosite asbestos Arch Environ Health 25 186 1972 3. I. J. Selikoff E. C. Hammond and H. Seidman presented at the meeting of the Working Group to Assess Biological Effects of Asbestos IARC Lyon France October 4 1972 4. Private communication with Dr. William J. Nicholson 5. P. E. Enterline P. de Coufle and V. Henderson Mortality in relation to occupational exposure in the asbestos industry J. Occup Med 14 897 1972 bestos 6. P. E. Enterline P. de Coufle and V. Henderson Respiratory cancer in relation to occupational exposures among retired as- bestos workers Brit J. Ind Med 30 162 1973 7. J. C. McDonald Cancer in Chrysotile Mines and Mills paper 29 presented at Conference on Biological Effects of As- IARC Lyon France October 2-5 1972 8. Environmental Asbestos Health Effects and Recommended Standards Illinois Institute for Environmental Quality De- cember 1972 available from Environmental Health Center P.O. Box 6998 Chicago IL Resource 9. Private communication with Dr. Arthur M. Langer 10. Private communication with Dr. Richard J. Thompson 11. Reserve Mining Company et al v United States of America et al United States Court of Appeals Eighth Circuit June 4 1974 p 12 Authors Response We are gratified to learn of the interest in our article The points which Dr. Plumlee raise are certainly worthy of comment Dr. Plumlee 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 this time The criteria of mesothelioma was selected as the basis for developing the proposed ambient air quality asbestos standard of 30 m based on a 30 day average sample be- cause 1. As Dr. Plumlee stated the high frequency of lung cancer in the general population does make it difficult to relate 1214 a given case of bronchiogenic carcinoma to asbestos exposure with the high degree of probability that exists for mesothelioma and 2. Some investigators maintain that the smaller asbestos fibers those fibers less than 5 microns in length most likely encountered in the ambient air as Dr. Plumlee has stated the larger asbestos fibers settle out of the air first leaving a greater proportion of small fibers are incapable of producing lung cancer however it has not been demonstrated that these short asbestos fibers are incapable of inducing mesothelioma Journal of the Air Pollution Control Association 2014 August 13 08:5 at \$ 50.169 by Downlade Dr. Plumlee states that mesothelioma frequency is not proportional to exposure however investigations of the distribution of mesothelioma in occupationally exposed individuals indicate a definite correlation between exposure to asbestos fibers and mesothelioma incidence As was stated in the article the boundaries of the asbestos 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 Environmental Health Resource Cen- ter EHRC decided to extrapolate the available occupa- tional data by using a linear effect relationship.The authors agree with EHRC Admittedly more improved quantitative information concerning 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 as possible to refine the asbestos mesothelioma incidence 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 be achieved control equipment other than fabric filters which yield 95 control e.g. wet cyclone Plants which are currently meeting the no visible emissions standard without the use of fabric filters cannot be expected to in- stall fabric filters Furthermore best available control tech- nology can mean different things to different people Who is to decide what is best In our opinion a numerical standard would be 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 standard even with fabric fil- ters The reentrainment of asbestos fibers into the ambient air at some later time or their ultimate fate was not considered when the emission standard was developed however the significance of this omission is unknown at this time Dr. Plumlee seems to have confused asbestos fibrils i.e. ultimate asbestos fibers 200 to 400 ^ in diameter and often 2000 ^ or smaller in length with asbestos fibers which in general can either be less than or greater than a micron long with varying diameter sizes Dr. Thompson estimated that there were approximately 100,000 to 1,000,000 asbestos fibrils not fibers in a nanogram of asbestos Wesolowski reported that there were approximately 6000 to 280,000 arithmetic mean of 110,000 asbestos fibrils per nanogram of asbestos.11 Dr. Thompson also estimated that there were 100 asbes- tos fibrils per fiber visible under the electron microscope.10 Thus assuming 100 fibrils per fiber and 100,000 to 1,000,000 fibrils per nanogram there would be approximately 1000 to 10,000 asbestos fibers not fibrils per nano- gram of asbestos We used 1000 fibers per nanogram in the development of our conversion factor relating asbestos fibers greater than 5 microns in length to nanograms of as- bestos Dr. Nicholson's estimate of 1 fiber greater than 5 microns in length per nonogram of asbestos appears to be consistent with our assumption i.e. 20 asbestos fibers greater than 5 microns in length per nanogram of asbestos Furthermore on the basis of assuming that most chrysotile asbestos fibers have a hollow cylindrical form with an aver- age outer diameter 4 to 12 times the inner one we calculate that there would be about 40 to 65 asbestos fibers 5 mi- crons long with a 3 length to width ratio per nanogram of chrysotile asbestos The Battelle Columbus Laboratory reported that on the average composite data from 88 am- phibole analyses there were 26 amphibole asbestos fibers greater than 5 microns in length per nanogram of amphibole asbestos.13 Thus while the conversion used to relate asbestos fibers greater than 5 microns in length to nanograms of asbestos is not perfect it seems to be reasonably accurate 20 vs. 26 and would certainly not introduce errors of 1000 or more into our asbestos mesothelioma incidence envelope as Dr. Plumlee claims The accuracy of the measurement technique used by Battelle to determine the chrysotile asbestos concentration of ambient air samples was reported to be 50 based on the analyses of activated chrysotile sample 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 as possible In conclusion we feel that our study provides a reasonable basis for requiring asbestos emissions to be 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. Environmental Health Resource Center News Illinois Institute for Environmental Quality Chicago IL Issue # 12 1974 2. P. Gross Is fibered asbestos dust a biological hazard Arch Environ Health 29 115 1974 3. Health Effects and Recommendations for Atmospheric Lead Cadmium Mercury and Asbestos Environmental Health Resources Center State of Illinois Institute for Environmental Quality Report #II 73-2 Chicago IL 1973 J. F. Know S. Holmes R. Doll and I. D. Hill Mortality from lung cancer and other causes among workers in an asbestos textile factory Brit J. Ind Med 25 293 1968 5. H. C. Lewinsohn The medical surveillance of asbestos workers Roy Soc Health J. 92 1972 6. M. L. Newhouse A study of the mortality of workers in an as- bestos factory Brit J. Ind Med 26 294 1969 7. M. L. Newhouse G. Berry J. C. Wagner and N. E. Turok A study of the mortality of female asbestos workers Brit J. Ind Med 29 134 1972 5 8. I. J. Selikoff J. 5 and E. C. Hammond Asbestos exposure and neoplasia and Med Assoc 188 22 1964 9. J. Stumphuis Epidemiology of mesothelioma on Walcheren Island Brit J. Ind Med 59 1971 10. R. J. Thompson personal communication May 7 1975 11. J. J. Wesolewski Asbestos in the California Environment Air and Industrial Hygiene Laboratory Report AIHL 164 California State Department of Health Berkeley California May 1974 12. Asbestos in the Great Lakes Basin with Emphasis on Lake Superior A Report to the International Joint Commission from the Great Lakes Research Advisory Board February 1975 13. C. W. Melton personal communication February 13 1975 Mr. Bruckman is principal air pollution control engineer and Mr. Rubino is assistant director of the Air Compliance Unit Engineering Section Connecticut Department of Environmental Protection State Office Building Hartford CT 06115. This paper was presented as Paper No. 74-222 at the 67th Annual Meeting of APCA at Denver in June 1974 Dr. Plumlee whose discussion of the paper is also presented here is a medical science adviser with the U. S. Environmental Protection Agency December 1975 Volume 25 No. 12 1215