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Asbestos and Disease: An Industrial Hygienist's Perspective MORION COKVPh I). C SI* -- I'mlessoi and IJncctur. Division ol lnvironmcMal Health Kiiginccuntt. School ol Hygiene aiul 1`uhlic Health. Johns Hopkins l mvcrsin. 615 North Wolle Street. Kiiltinmie. MO 21205 Introduction I was noi personally acquaint'd with Donald Cummings, but I know of him. At the Harvard School of Public Health in the mid-1950s he was occasionally referred to as part ol the lamous Saranac Laboratory team consisting of Leroy Gardner. Homer Sampson and Don Cummings. Cummings was the hygienist, a man exhibiting professional compe tence. curiosity and energy relative to investigation of the dust silicosis tuberculosis interaction. He was said to have had an abiding belief in our capacity to unravel this complex biological interaction, as well as other pncumocomotic dis eases ol our industrial society. His tragicand untimely death in an airplane crash in 1942 curtailed the lile ol a man w ho. by all accounts, had his major scientific and prolessional contributions ahead ol him. It is a privilege and an honor to be selected .to deliv er this address honoring Donald Cummings. The subject ol this lecture is an industrial hygienists per spective on asbestos, and United States approaches to reduc ing the risk of disease to those inhaling this extraordinary material. Asbestos has probably received more attention in the United Slates and worldwide than any other potentially toxic agent addressed by practitioners and investigators in the lields of industrial hygiene, occupational medicine. Dr. Morton Corn, Ph.D., CIH, cur rently is Professor and Director of the Division of Environmental Health Engineering, School of Hygiene and Public Health at The Johns Hopkins University, where he has been a faculty member since 1980. Prior to his appointment at Johns Hopkins, Dr. Corn advanced through the ranks from assistant to full professor while on the faculties of the Graduate School of Public Health and the Depart ment of Chemical Engineering at the l niversity of Pittsburgh (1962-1979). A leave of absence from 1975 to 1977 pres ented him the opportunity to serve under President Ford as Assistant Secretary of Labor for Occupational Safety and H ealth in the United States Department of Labor. While obtaining his undergraduate degree in Chemical Engineering from Cooper School of Chemical Engineer ing Dr. Corn worked summers as a Research Assistant for the U.S. Atomic Energy Commission, thus beginning a career that has earned him numerous awards, fellowships and other honors. Beginning with the New York State Regents Scholarship, which he was awarded from 1951-1955, Dr. Corn has amassed a lifetime of achievements. including the National Science Founda tion Postdoctoral, the John Simon Guggenheim Fellowship, the USAEC Fellowship, a wards for published works, and invitations as guest speaker and lec turer at conferences throughout the world. Dr. Corn also has served on various panels and committees, such as the Environmental Protection Agency Science Advisory Board (1977-1984) and the Office of Technology Assessment Committees on Control Technology in the Workplace and Hazardous W astes. In 1981 Dr. Corn was elected Vice Chairman of the American Conference of Governmental Industrial Hygienists, succeeding to Chairman in 1983. In 1984 he w as elected President of the Associa tion of Universities in Occupational Safety and Health. Dr. Corn currently chairs the Industrial Hygiene Commitee of the International Resource Center in Occupational Safety and Health; and is a member of NIOSH's Mine Health Research Advisory Committee. Among his other memberships. Dr. Corn also belongs to the American Association of University Professors; the awards committee of the ACGIH; the American Industrial Hygiene Asso ciation, as a member of the Manage ment Committee; the American Insti tute of Chemical Engineers, full grade; American Public Health Association; Air Pollution Control Association; Brit ish Occupational H ygiene Society; Society of Occupational and Environmental Health, founding member; and numer ous others. Dr. Corn's published works include papers, book chapters, and conference and symposia proceedings dealing with the subjects of aerosol physics, air pollu tion. industrial hygiene, safely in the workplace and public policy. Ind Hyg Assoc J (47} September 1986 10003304 515 occupational epidemiology and toxicology. One could argue that more is known about the toxicity of asbestos and the dose-response curve for its inhalation by those exposed than is known about any other industrial material. Asbestos has created economic crises in selected corporations responsible primarily for its production and product distribution, caus ing two major U.S. corporations to enter into Chapter 11 bankruptcy.'1' The concern for asbestos has spread from those exposed occupationally to those experiencing nonoccupational exposure. Asbestos has precipitated regulation of the nonoccupational env ironment by the Environmental Protection Agency and the Consumer Product Safety Commission in the United States. One could rev iew our experience with the health effects of asbestos from the perspective of the lawyer: asbestos has set precedents in personal injury and property damage litiga tion. One could also view the asbestos experience as a case study in the evolving occupational and en\ ironmental medi cal literature, where scientific and technical precedents have been established. There are numerous facets to the asbestos story and one could select different vantage points to observe and evaluate those facets. I focus here on the indus trial hygienist perspective. What can we learn, as indiv iduals and as a profession from this experience, this extraordinary case of societal utilization of a valuable material and the associated growing recognition of its disease potential? Background to the Occupational Standard My introduction to asbestos occurred in 1955 as a graduate student in Industrial Hygiene at the Harvard School of Public Health. Our class studied the properties of dusts and fine particles in general, under the tutelage of Professors Leslie Silverman. Philip Drinker, and Charles Williams. In retrospect. I was instructed extremely well on the technical assessment ol airborne concentrations of asbestos. At that time we evaluated asbestos dustiness according to the American Conference of Governmental Industrial Hygien ist's Threshold Limit Value (TLV) guideline of five million particles per cubic foot of air determined by light micros copy. Students were instructed by Dr. Williams in the appropriate sample collection by midget impinger. slide preparation, and microscopic counting procedures. Perhaps the first lesson to be derived from this experience was that we were norurged to critically evaluate the documentation of the TLV. The Dreesen study,J' of textile workers was the basis for the TLV guideline. It was an extremely limited cross sectional epidemiological investigation, characterized as follows in the first edition of the Documentation of Thresh old Limit Values, published by the ACG1H in 1962: "The present threshold limit relates to the prevention of asbestosis. It was recommended by Dreesen. et ai. after study of 541 employees in three asbestos textile plants using Chrysotile. Only three doubtful cases of pneumoconiosis were found in those exposed to dust concentrations under 5 mppef. whereas numerous well marked cases were found above 5 mppef. Counts were from impinger-collected samples in ethyl alcohol and distilled water. Both fibrous and non-fibrous particles were counted, but the latter greatly predominated. While chemical analyses of collected samples of air borne dust corresponded to those of settled dust sam ples it is believed that dust counts of particulates by conventional methods can be expected to give only an indirect measure of the risk of asbestosis because of the great relative importance of long fibers."1^ The above was the total documentation for the guideline in 1962. In 1955 the brief discussion of asbestos disease found in the book Industrial Dust by Drinker and Hatch^' was the major reading for graduate industrial hygiene stu dents on the rationale for the guideline. The TLV was for pure chrysotile fiber. In practice. U.S. industrial hygienists utilized the TLV for all situations where airborne asbestos was encountered. It was not until 1968 when the British Occupational Hygiene Society (BOHS) published their occupational hy giene standard for asbestos that a specific level of risk for basal rales and x-ray changes was offered for asbestosis.1 " 1 TABLE I U.S. Asbestos Standards'1''' Million particles/ per cubic ft. Fibers/ cc STEL.* fibers/ cc 1938 1946 1970 1971 1971 1975 1976 1976 1983 1984 ACGIH OSHA NIOSH OSHA OSHA Recommended Adopted Adopted Proposed Emergency Proposed Adopted Recommended ETS Proposed TLV TWA 5 5 2 - - - 30' 30' 12' 5 2 05 2 01 05 0 4 or 0.2 10 5 10 0.5 'Short Term Exposure Limit 'Approximate tiber equivalent 10003305 516 Am int) Hyg Assoc J (47) September 1986 TABLE II Factors Included in EPA Exposure Assessment Algorithm"" Condition of material Water damage Exposed surface area Accessibility Activity and movement Air plenum or direct air stream Friability Asbestos content and others instructed in industrial hygiene in the I950'sand I960's were aware of the limitations of measurement tech niques for asbestos-in-air. but were not seriously concerned with the adequacy of the TLV and were not addressing the need for change. Had our instruction focused more heavily on understanding the basis for the numbers in theTLV's, the uncertainties would probably have caused us great discomlort and concern. The BOHS publication profoundly affected the manner in which I assessed asbestos-in-air in the field during the late I960's. I obtained midget impinger samples by the traditional U.S. method, but also obtained simul taneously collected membrane filter samples, expressing results as both mppcf (U.S. method) and fibers cc of appropriate sire (BOHS method). Of course, part of the growing concern of hygienists was the increasing realization of the carcinogenic properties of inhaled asbestos, a subject soberly addressed in the 1968 BOHS standard. Why is familiarity with the basis for a guideline and its weaknesses essential to the hygienist? While the standard is a single number, the interpretation of air sampling results and the accompany mg recommendations w ill inevitably be shaded by the hygienist's insight into the basis for the standard. Standards, as we often repeat, are not fine lines between acceptablcand unacceptablecondiiions(orrisks). However, how we place the results in perspective for concerned clients will be a reflection of our own awareness of the "softness" or "hardness" of documentation supporting the guideline or standard. In the 1971 third edition of the Documentation of Threshold Limit Values by the ACGIH there is a more critical paragraph on the Drccscn study, as well as a lengthier de scription of results relevant to a standard. The Dreescn study is further treated as follows:16' "A conference on the biological effects of asbestos in 1965 called attention to the very real probability that the 5 mppcf limit recommended by Dreesen is inade quate to give complete working-lifetime protection against all forms of asbestos. Medical data on which the limits had been based were inadequate: more than PRODUCTION PROCESS Figure 1 -- Conceptual model of the three zones of influence to control workplace hazards. '1'' Ina Hfg Assoc J (47) September. 1986 10003306 517 hall of the asbestos workers studied were under 30 years of age and thus provided an insufficient exposure time for asbestosis to develop. Of the 105 workers exposed to less than 5 mppcf. 82 had worked less than 5 years: 101 less than 10 years: only 4 had more than 10 years exposure. Seven of 36 workers exposed to 5-9.9 mppcf had asbestosis; 3 of 50 workers exposed to 10-19.9 mppcf for less than 5 years had asbestosis. Moreov er, it was a "point-in-time" study: many of the ill were missing and the dead uncounted, hence not considered in the over-all evaluation of the limit." The recommended guideline based on the Dreesen study had stood for 33 years without critical reappraisal in the U.S. until the 1965 New York Conference' ' and the 1968 BOHS recommended standard prompted reappraisal. Let me be clear: I am not criticizing the TLY committee. The responsi bility for reexamination of the standard was and is that of practicing industrial hygienists: it is too important a matter to leave entirely to the toxicologists. Clearly, the first lesson ofthe asbestos storyfor industrial hygienists, particularly at a time when the field and this association is expanding to include industrial hygiene tech nicians. is that one must critically examine the supporting documentationfor a standard when utilizing it infieldsitua tions. Fortunately, the Occupational Safety and Health Act. with its requirements for adherence to the Administrative Procedures Act for standards promulgation, necessitates agency publication of a Proposal fora standard, followed by comments and in every case to date, a public hearing. These procedures should force currently practicing industrial hygienists to familiarize themselves with the uncertainties of permanent OSH A standards. The limitation of this proce dure for enforced learning is that OSHA has only passed 28 permanent health standards during its sixteen year history. The majority ol standards in OSHA are still Permissible Exposure limits, as listed in Table Z-l of the OSHA General Industry Standards.1''1 They lack extensive documentation and associated engineering, medical, environmental, work practice and administrative controls, lhus. the burden remains on the hygienist to familiarize his hersell with the epidemiological and toxicological literature on which stan dards or guidelines are based. The passage of a new standard by OSHA will, ol course, involve public review ol the health related data base. How is the hygienist to integrate this type ol knowledge into work and the discharge of his or her duties? The approach must be to indicate to a client and to those poten tially affected in the work environment the airborne stan dard involved, but to moderate this with lull clarification ol the uncertainties associated with the numerical values of permissible exposure lime weighted average or peak values. I he degree of concern of the industrial hygienist must be related to the relative uncertainties ol the standard. It is only in this way that the practice ol industrial hygiene will be a science and an art. and not a mindless application ol numbers and techniques. The Ha/ard Communication Standard ol OSHA and stale "right-to-know" laws should also serve to develop this approach. 518 Surrogate Measures of Exposure In addition to the basis for the asbestos standard, we should briefly address the sampling methodology for airborne fiber concentrations. The early midget impinger mppcf method ology involved counting all particles present, although there was good indication at the time of adoption that this surrogate for theactive agent may not apply in environments w here all materials processed or used were not asbestos. The heritage of adoption of this weak surrogate measure for fibers was felt throughout the I960's. For example. I was involved as consultant to the Pittsburgh Corning Corpora tion and designed dust control systems lor their Port Allegany. Pennsylvania and Tyler. Texas Unibcstos plants. These facilities later became the subjects of major personal injury litigation: unfortunately, large numbers of people contracted asbestos disease at these sites. In both the Tyler and Port Allegany cases 1 reviewed reports of practicing hygienists prior to undertaking my own surveys and dust control systems design. [A dust control system was installed in Port Allegany. Pennsy lvania but not in the Tyler. Texas plant. These cases can now be discussed because the litiga tion has been completed.1*'] The hygienists had misinter preted the 5 mppcf guideline* and had counted fibers, instead of particles and fibers, w hile determining adherence to the mppcf standard. Because it was a mixed material environment, the fiber counts were low when compared to the standard, as one would expect. Therefore, startling con ditions ol dustiness were encountered in Tyler, conditions addressed in prev ious hygienist reports and concluded to be in compliance with the 5 mppcf TLV for asbestos-in-air. The lesson suggested is that adoption ofa surrogate meas ure for extent of exposure to a toxic agent, although appropriate in an isolated or particular situation, may not be appropriate to many other situations. There tnust be an extraordinarily high level of care andforesight when a sur rogate in assessment is adopted. I ndccd. w e must as a profes sion take every precaution to make sure our members under stand the compromise inherent in the surrogate measure. Such a measure was adopted in the OSHA Coke Oven Standard. 1 he benzene soluble organic portion of the res pirable dust was invoked as the surrogate measure lor the risk ol exposure to coke ov en lumes. a v ery complex mixture of potentially toxic materials. In this case. OSHA proce dures. including public hearing and wide discussion ol the strengths and weaknesses ol the surrogate measure resulted in the compromise being widely understood. The current phase contrast microscopic method for examination ol filter samples containing asbestos fibers does not measure asbes tos libers exclusively, a result ol technical imitations ol the microscope illumination. In mixed material environments a very prudent measure of exposure is obtained. Unfortu nately. this is not well understood by many hygienists and the 2 I ccOSHA standard istilten thoughtlessly invoked in all environments. I will later return to the problems of a Because the plant was producing pipe insulationtor the U.S Navy, it was covered by the Walsh-Healey Public Contracts Act. the mppet TLV was an enforceable Federal Standard under this Act 10003307 Am Inn H>e Assoc 1 [// September 1986 mii logate measure lor asbestos in regard to nonoccupational exposure 10 asbestos. I will not further dwell on the safety laetor or lack ol safety factor the use of surrogate measures may inelude: my point is that those who use such surrogates nuist vers clearly understand what they are doing. I.inks to the Past l nder present regulatory procedures in this country. OSH A permanent health standards lor airborne contaminants icquire that an initial determination be made ol the concen tration of the agent in air. If the concentration is above a triggering permissible exposure limit, periodic surveillance is undertaken. When the measurement lechniqueand approach to asbestos evaluation in the environment was altered and the membrane filter method introduced in the late I960's. ell orts were not made to link this assessment methodology to past measurement techniques using the midget impingerand the ntppcf method. Today we are struggling with so called `retrospective industrial hygiene."1"" In order to project the reduced impact of lowering standards lor potentially toxic materials, it is necessary to havelairlyreliable dose-response curves based on past exposures and health effects unfortu nately already experienced. There must be a period ol simul taneous env ironmcntal evaluation using new and old method ologies for assessment, with subsequent correlation of results. When we changed from the midget impinger mppcf technique to the membrane filter phase contrast microscopy technique, there should have been a required period ol dual measurement to permit conversion of old measurements to the new framework. Such a required period could be part of the regulatory requirements or could be voluntarily under taken by the industrial hygiene profession. We are now guessing at the conversion factors. I have personally simu lated phased-out past production processes to perform simul taneous exposure measurements by these two measurements. Surely the lesson of this experience, so vividly illustrated a ith asbestos where the projection offuture disease is so important."u is that as a profession ice must take steps to insure simultaneous measurement by new and old techniques when an assessment methodology is changed. Non-Occupational Exposure to Asbestos Asbestos concerns spanned the years from the 1930's until the present time. They overlapped the creation of the Occu pational Safety and Health Administration in 1970. One ol the first issues addressed by OSH A was asbestos: in 1972 a permanent federal standard for asbestos was promulgated. I able I indicates the consistent lowering of the federal per missible exposure limits.'*-'1 We are currently awaiting a lurther reduction in the federal standard. OSHA made it very clear to me and to other hygienists that the procedure up to that time of reporting our results to employers or clients exclusiv ely, would not fulfill duties and responsibili ties assigned to us by law. We are in an entirely dtflerent phase of discharging our responsibilities by sharing informa tion. The implications ol the Act for industrial hygienists was a subject that I addressed in 1976.11,11 It remains a dilli- Ina Hyg Assoc J (47) September 1986 cult subject area to sort out. Current hazard communication standards at the federal level and right to know standards at the stale levels are articulating the types of concerns that we attempted to resolve as individuals or as groups ol profes sionals during the I970's and early l9X0's. Needless to sav. the awareness ol these responsibilities suggested there was justifiable concern and that there should be scrutiny ol other areas ol asbestos exposure, areas not covered by the Occupa tional Safety and Health Administration because they do not occur in places ol employment involving exposures to employees. This category ol concerns has been called non occupational exposure. The asbestos story provided evi dence that exposed workers could carry asbestos from the workplace to the home, thus causing exposure of those not employed. Awareness ol this potential for contamination and the use ol asbestos in other environments haslocused on asbestos in schools and buildings, an area addressed by the Environmental Protection Agency (EPA) under the loxic Substances Control Act. It is an area engaged in complex property damage and third party personal injury litigation. The non-occupational asbestos exposure area also suggests certain lessons lor the industrial hygienist: I'll now address several ol these. Air Sampling for Asbestos in Nonoccupational Environments The EPA in a series of guidance documents often referred to as the Orange Book." the Blue Book."" and the Purple Book1"" indicated early on that theagency had a very cry stal lized view of the role olair sampling inevaluatingthe risk ol exposure of building occupants to airborne asbestos. In the 1979 orange document the following statement is made in Chapter 7 on Exposure Assessment: "Air sampling is inappropriate to estimate asbestos contamination and exposure. In the school environ ment. it is virtually impossible to establish exposure potential using standard air sampling techniques.""" Instead of relying on the well-established science and art ol air sampling. EPA adopted an algorithm, a device that could be viewed as a tool for qualitative risk assessment. The EPA ollered a series of relevant environmental factors, listed in Table II. Numerical weighting lactors were then assigned to each environmental laetor and a formula was used to derive a numerical score for the given situation. Based on the algorithm score, the responsibile party was directed to take immediate action (removal) or id postpone action. The environmental factors weighting was biased towards a resulting score which dictated immediate action, in most cases. What was not known by the professional community and the public in 1979 when EPA issued the first guidance document was that the algorithm had never been tested for its correlation with airborne asbestos concentra tions in different env ironmenis. Subsequently, two contrac tors to EPA indicated the poor correlation of the algorithm scores with airborne fiber measurements."'"!' The only highly consistent env ironmental factor was water damage to the material Other investigations ol algorithm validitv 10003306 sis reached similar conclusions about the EPA algorithm usefulness.'11" The need to correlate an algorithm with airborne fiber concentrations is essential if risk is to be estimated by a method other than measuring airborne concentrations. Fig ure I is a bedrock conceptual framework for exposure to emironmcntal agents.120' The mere presence of a source or agent is a potential hazard; the transmission of the agent to the Teccptor is necessary for a potential hazard to become a real hazard. Asbestos in a building is a potential hazard; asbestos-in-air concentration is the measure of that hazard being realized. The issuance of the 1979 guidance document by EPA in the absence of algorithm validation and in the presence of initial air sampling results discrediting the algo rithm. can only be viewed as agency arrogance bordering on "chutzpah. In 1983 the "blue book" by EPA again discussed air sampling and the algorithm. It indicated that two of the eight factors assumed to correlate with measured levels of asbestosin-air did. indeed, do so. These were water damage and the proximity of the material to an airstream created by a venti lation system. A report to the EPA by Battelle Memorial Institute was the basis lor the conclusions.1'2' In spite of these findings regarding the lack of validation of the algorithm in terms of fiber-in-air concentrations. EPA in the blue book recommended use of six of the factors to predict "fiber release potential." Once again, the agency recommended use of factors not validated by correlation with the property to be predicted, i.e.. liber release potential, a term not well defined by the EPA to this day. What about measuring airborne asbestos in nonoccupalional environments? In the blue book of 1983.'1 " EPA states the following in Section 3.2.3.; "Another proposed approach to assessing the need for corrective action is to measure asbestos fibers in the air. At best, this approach provides information only on current asbestos contamination and no information about the potential for liber release and future air levels. Moreover, the use of air monitoring as an assessment tool involves substantial technical and economic problems which limit its use even for deter mining current levels of contamination." After devoting two additional paragraphs to the limita tions of air sampling, the following sentence concludes the air sampling discussion: "Given the limitations. EPA docs not recommend the use of air monitoring for assessment purposes at this time." In the latest "purple book,"'"'1 EPA states that it does not recommend air monitoring "as a primary assessment tool at this time." Algorithm factors are still endorsed, but with qualitative scores only. Air sampling /.v recommended for post abatement evaluation. 520 Why have I dwelled on this EPA asbestos story? The lesson to the industrial hygiene profession is that u p must alwa.s be alert and respond to obviously incorrect evaluations of some of the principal scientific tools of our profession. Our associations did not challenge the EPA in its denigration of air sampling. Much to my dismay, some hygienists have appeared in court on behalf of plaintiffs to reiterate EPA's downgrading of air sampling as a scientific tool. It eludes me as to how these indiv iduals can. on the one hand, repeat the EPA position and then on the other hand, proceed in their daily utilization of air sampling methods for assessment of airborne hazards in a large variety of other environments. What is unique about asbestos in indoor environments? Risk Assessment in Nonoccupational Environments Another lesson stemmingfrom shift ofconcernfor asbestos in the w orkplace to asbestos in the nonoccupational setting is that this transition will occur with other potentially toxic agents. We must be prepared to place nonoccupational risks to potentials toxic agents in perspective with regard toother risks to lifeand health in the nonoccupational setting, utiliz ing the best techniques available. Risk assessment is cer tainly not an exact science, but in its present state of devel opment it is a valuable input to the assessment of health hazards, as stated by the National Academy of Sciences.122' Risk assessment highlights relevant factors related to the risk under scrutiny and it often permits scientific assump tions. or "inference guidelines"122' to be made in order to estimate the risk quantitatively. If hygienists abandon these matters of risk assessment, others may lose sight of the health component of the dialogue. The current situation w ith regard to asbestos risk in non-occupational settings is a mess becau>e EPA has never addressed the magnitude of the risks involved. Table III displays the ranges of airborne con centrations of asbestos in non-occupational settings in build ings and schools. The lifetime risks associated with nonoccupational exposure to occupants of buildings and schools have been estimated by the National Academy of Sciences.'2'" by a Royal Commission of the Province of Ontario. Canada.12" and most recently by Hughes and Weill.'2'" Table IV indi cates lifetime deaths per million exposed attributable to six years of asbestos exposure in schools. The exposure concen trations assumed are reasonable based on Table III data. In my opinion, the model used for Table IV is a defensible one. but you must refer to the original article to follow its devel opment. Hughes and Weill compared these risks to other commonplace risks in life. The upper estimate of approxi mately fifteen lifetime excess deaths (mixed fibers at 0.003 I cc) would constitute an average annual rate of approxi mately 0.25 deaths per million exposed. The latter rate com pares with approximately 1200 deaths for long-term smokjn^. 15 for bicycling. 15 lor ingestion inhalation of lorcign objects and 10 from playing hjgh_school foot ball. The upper estimate ol an avcrageannual rate of0.25 deaths per million exposed weald be equivalent to 0.75 annual U.S. deaths, based on EPA's estimate of 3 million students currently exposed.'2'' 10003309 Am !nd Hyg Assoc j (t?) September 1986 Postclearance Standard After Removal I he least defensible and perhaps strangest aspect of the current U.S. approach to non-occupational asbestos, is the standard for a clearance concentration for asbestos-in-air lolloping a major abatement activity. Three states, i.e. Massachusetts. New Jersey and Rhode Island, have adopted standards of 0.01 f. cc after "aggressive sampling." Air sam ples are evaluated by the PCM. or NIOSH method. A brief review of Table III will reveal that before removal of asbestos in the building air concentrations were, on the average, at least an order ol magnitude less than the clearance concentra tion in the majority of buildings. The justification for the standard is apparently that, because samples arc collected after "agressivc" sampling and because evaluation by the PCM method results in all fibers of a certain size being counted, th'c 0.01 f cc standard actually represents an asbestos-in-airconcentration far below 0.01 f cc. Thiscould or could not be a valid rationale: data have not been col lected to accept or reject it. Of course, the clearance standard could W'cll be a license to permit building contamination to increase, resulting in more airborne asbestos fibers after removal than before. I am already aware of such cases, but data have not been systematically collected. The clearance standard is a so-called concession to "prac ticality." Post removal air evaluation by electron micros copy has not been deemed feasible. PCM is rapid and would permit efficient conclusion of the removal contract and release of contractors. However, the risk to building occu pants from inhalation of asbestos could well be greater after removal than before removal, w hen the original risk was pre sumably judged sufficiently compelling to trigger removal! The illogic of this aspect of non-occupational exposure to asbestos is sobering if one considers the large expenditures of effort and money w hich may increase, rather than decrease occupant risk to asbestos disease. I question the conclusion that electron microscopy is not feasible for postclcarance evaluation ol air samples. Indeed, in my opinion it is the only way to certify an abatement effort as satisfactory. The standard should be that post clearance air concentrations arc. on a statistically valid basis, lower than preabatement concentrations. If they arc not. contractors should clean the premises until they are. What can we conclude from the juxtaposition oil he above estimates of risk from nonoccupational exposure to asbes tos. the manner in which EPA has proceeded to regulate this risk and the current level of public concern lor this potential hazard? Obviously, those responsible for national regula tory policy have lost sight not only of some well established principles of environmental assessment, but of comparative or relative risks and the setting of priorities. Today, members ol the public need only learn of the presence of asbestos in a building and they want it removed. This attitude can be traced to the manner in which EPA presented the subject: it failed to relate theasbestos risk to other env ironmental risks. It is still not too late for our professional associations to issue a scientific document, albeit abbreviated, which states our position on these matters. Such a document would not be responsive to immediately pending specific regulation: there fore. the urgency w ith w hich this must be done is not great. We can utilize a democratic form of assessing membership input to reach a position on the value of industrial hygiene tools in assessing the risk and the value of risk assessment in comparative risk delineation re: asbestos in non-occupational env ironments. ind. Hyg Assoc J (47; TABLE III Summary ol Asbestos Exposure Samples in Different EnvironmentsJ< * Sample Set No. of Samples Measured Concentration ng/m Median 90th Percentile Equivalent Concentration (fibers/cc)** Median 90th Percentile Air of 48 U S cities Air in U.S Schoolrooms without asbestos Air in Paris Buildings with asbestos surfaces Air in U.S Buildings with cementitous asbestos Air in U.S. buildings with friable asbestos 187 31 135 28 54 1.6 163 18 7.9 19.2 6.8 0 00005 000023 72.7 0 00054 0 00242 32 2 0 00006 0 00107 19.1 000026 0 00064 96.2 0.00064 0 00321 'Table III does not include all references and associated results, as contained in the more extensive NAS table ' 'Based on conversion factor of 30 *jg/m - 1 liber, cc September. 1986 10003310 521 TABLE IV Estimated Number of Lifetime Death* Attributable to 6 Yr of Asbesto* Exposure in Schools (Per 10" Exposed) By Fiber Type and Average Concentration''""* Lung Cancer*. Mesotheliomat Total 0.001 f/cc Mixed fibers Chrysotile only 0 003 f/cc Mixed fibers Chrysolite only 06 (0.3 to 1.2) 0.6 (0.3 lo 1.2) 1.9 <0.9 to 3.7) 19 (0 9 to 3 7) 44 (2.2 to 8.8) 09 (0 4 to 1.8) 50 (2.5 to 10.0) 15 (0.7 to 3.0) 13.2 (6 6to26.4) 2.6 (1.3 to 5.3) 15 1 (7.5 to 30.1) 45 (2.2 to 9.0) 'Refer to original article for model assumptions re: calculation of table entries The tripartite descriptor of industrial hygiene has been recognition, evaluation and control. The movement of asbestos concerns from the workplace into the non-occupational environment suggests that we should add "anticipa tion" lo these valuable descriptors of our activities. Antici pation. recognition, evaluation and control should be the future guiding lights of the field. Recently. EPA issued a proposal to sequentially ban asbestos usage in the United States.`',l Asbestos is a unique and valuable material. Can it be used in certain unique applications at an acceptable level of risk? That is an issue on which vveasa profession should sort out our views and make them known. Safety is a relative term: it is acceptable risk.1"'" Vhe tools ol engineering controls, combined w ith work prac tices and personal protective equipment usage can reduce the risk ol using potentially toxic materials to a level com parable to other commonplace risks in life. Should we ban a material from usage if it is not a trivial material with numer ous substitutes? Asbestos is not in the latter category. The setting ol a sequential asbestos ban leading to a total ban will establish a precedent that we. as industrial hygienists, should address publicly as a profession after crystallizing our viewpoint. Summary I have traced a personal thirty year journey ol involvement with asbestos in the workplace and the nonoccupational environment, one still in progress, in an attempt to extract selected lessons lor the industrial hygienist. Lessons for other professions, namely medicine, law and management have been studiously avoided in the interests of the scope of this presentation and permissible time. There arc certainly numerous other lessons to contemplate. The movement of asbestos from the occupational to the nonoccupational environment is a ease study that will undoubtedly be fol lowed in the luture by other potentially toxic materials. We must determine our position as a profession with regard to the tools we utilize, the procedures we follow, and our understanding ol our moral and legal obligations to prepare 522 lor the often scientifically and technically unsupportablc positions assumed by others, including governmental agen cies. in their zeal to bring about change. We must discourage the opportunistic distortion of professional practices in these matters, and must issue-well considered statements as a profession, statements relevant to the way these matters are addressed by society. We have a responsibility to lend per spective to these issues, to not permit understandably emo tional responses to documented past severe health effects in other areas, such as the case of asbestos in the w orkplace. to carry over into conditions of very low exposures in the public domain. We must remind people of the relevance of dose-response and toxicological principles to assessment of risk. These principles are very much in the professional tradition of Donald Cummings. Perhaps that is what this address is really about, namely a reiteration of principles and an appeal, that as a profession we reassert these principles in order to discourage and thwart their distortion in the marketplace. References V Brodeur, P.: Outrageous Misconduct. New York: Pantheon Books. 19B5. 2. Dreesen, W.C., J.W. DallaValle, T.l. Edwards, J.W. Miller and R.R. Sayers: A Study of Asbestos in the Asbestos Tex tile Industry. Pub. Htth. Bull. No. 241. Washington, D.C.: U S Pub. Hlth. Service. 1938. 3. American Conference of Governmental Industrial Hygien ists: Documentation of Threshold Limit Values. Cincinnati. Ohio ACGIH. 1962. pp. 11-12. 4. Drinker, P. and T. Hatch: Industrial Dust, 3rd Ed. New York: McGraw-Hill Book Co.. 1959. pp. 45-46. 5. Hygiene Standards for Chrysolite Asbestos Dust. Comm on Hygiene Standards. British Occupational Hygiene Soci ety. Ann. Occup. Hyg. f?:47-69 (1968). 6. American Conference of Governmental Industrial Hygien ists: Documentation ol Threshold Limit Values. 3rd Ed. Cincinnati. Ohio: ACGIH, 1971. pp. 17-19. 7. Whipple, H.E. (Ed.): Biological Effects of Asbestos. Ann. N Y Acad. Set. 132:1-766 (1965). 8 General Industry. OSHA Safety and Health Standards 29CFR1910.1000, Table 2-1. OSHA U.S. DOL. Washington. DC 9 Com. M.: Depositions in H. Yandle. ef at. v. PPG Industries Inc . ef a/. Civ. No. TY-74-3-CA. U.S. District Court for Eastern District of Texas. Tyler Div., taken in Washington. D C . Sept. 21. 1976; and A. Barber ef at. v. 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D.C.: National Academy Press. 1984. p. 220. 25. Royal Commission on Matters ol Health and Safety, Canada: Report on matters of health and safety arising from the use of asbestos in Ontario. Toronto. Ontario. Canada: Ontario Ministry of Government Services. 1984 26. Hughes, J.M. and Weill, H.: Asbestos Exposure-Quantitative Assessment of Risk. Am. Rev. flesp. Dis 133.5-13 (1986) 27. Asbestos; Proposed Mining and Import Restrictions and Proposed Manufacturing, Importation and Processing Pro hibitions. Environmental Protection Agency. 40CFR Part 763 FR Vol. 51. No 19, 3738-3759. Jan 29. 1986 28. Lowrance, W.W.: Ol Acceptable Risk. Los Altos. Calif: W Kaufmann. Inc.. 1976 pp. 75-101 ln<> Hyg Assoc J f<7) Seoler:;r 1986 10003312 523