Document Y9wM11n6J56pjrxaJLDLO3kdO

ARCHIVES OF ENVIRONMENTAL HEALTH VOLUME 19 July through December, 1969 American Medical Association Publication i EXHIBIT Summary *v of the background of probl in setting occupational expo, s over the years has, hopefully > impression that a tremenof investigation, research, and udgment has been brought to development of our ideas a> vlany problems remain to tv vith our present occupational dards, the industrial hygienist if a powerful tool in the con'ational health hazards. And physician must be continually jssibility that an occupational dard may not be sufficiently xi to be completely depend he health hazards within the ?en shown to be within the dards, he can have much asiis patients, the industrial cm- the benefit of a healthful mment. : Maximum Allowable Con<'rntm \ Atmospheric Contaminants. ]n,)< H6 (Nov) 1945. M.W.: Research in Indiwtri! hemical Industry, Brit J Indunr ) 1955. Jr.: Improved Communicatino lards for Daily Inhalation, Amrt ; J 17:129-185 (June) 1956. Hygienic Standards for Chrysolite nn Occup Hyg 11:47-69 (April* and Cook. W.A.: Maximum A1 lions of Atmospheric Impurities l (1:51-54 (Jan) 1949. Evaluation of Our Concepts <f nviron Health 10:Mo*549 (April1 H.J.: Soviet and American S(*n al Health, Arch Environ Health 1965. i.J., et al: Industrial Toxirolo*\ nion--Theoretical and Applietl. g Assoc J 25:185-197 (Man-h and Cook, W.A.: Current MAC USA, Proceedings of the tSth ress on Occupational Health. V i ot 3, Hygiene, Toxicology. Vienna: Verlag der Wiener , Sept 15-20, 1966, pp 5-8. 19 Current Problems of Setting Occupational Exposure Standards Herbert E. Stokinger, PhD, Cincinnati T HIS year marks the 25th anniversary of appearance of the first list of Threshold limit Values (TLVs). It would seem ap propriate at this quarter-century mark to evaluate not only what has been accom plished, but to define those problems that -till remain, in an effort to overcome the problems and to improve the limits and roake them more generally useful and effective. Committee Activities and Related Prob* Inns.--The TLV Committee has two major activities: development of TLVs and valida tion of TLVs. Most, but not all, of the problems stem from these two activities. Other problems arise from the misnsp and Submitted fer publication Feb 3, 1969; accepted f A ,1, Fiom the Department of Health. Education, and JMtore, Consumer Protection and Environmental Hmith Service, Environmental Control Administra- Bureau of Occupational Safety and Health, Cinnneti Head before the 28tb annual AMA Congress on 'fcrupeiiotta] Health, New York, Oct 1, 1968. R*Pnt requests to Department of Health, Educaand Welfare, Consumer Protection and Environ- *wtal Health Service, Environmental Control AdBureau of Occupational Safety and 'ehn, 1014 Broadway, Cincinnati 45202 (Dr. Stckcw). mishandling of the TLVs by government agencies (military) or by the legal profes sion, by company representatives (sales men) and some industrial hygienists who have not yet got the complete message. Composition of TLV Committee.--Be cause there has been some question in the minds of some physicians on the composi tion and fitness of the TLV Committee, it is important at the outset to identify the pro fessional standing and activities of its mem bers. Of the 14-man committee: physicians --five (one representing Canada); indus trial hygienists, toxicologists--eight could be counted here; industrial hygiene engi neers--two; analytic chemists--three; pa thologists--one. Most are individuals of national repute, several have international reputations, but probably more important, many of the com mittee have a background of long experi ence in occupational health, and still more important, several are actively engaged dai ly in evaluating plant situations--and note also, membership is derived from the most highly industrial states. To my mind the accumulated background and experience of this committee provides a perspective in Arch Environ Healtk--Vol 19, Aug 1969 278 OCCUPATIONAL EXPOSURE--STOKINOER occupational health and animal toxicity data of which it is difficult to find the equal. The Problem of Data Acquisition."--Thus we have the requisite group to handle the data and recommend limits, but why, in the face of several hundred new products placed on the market annually, is the TLV Com mittee able to establish annually only two dozen or so limits for new substances? These relative figures point up the greatest problem facing the Committee: The acquisi tion of industrial hygiene data of the appro priate type to develop TLVs on new sub stances. ~------- / The TLVs are industry's valuesTBut ini dustry generally does not develop anywhere near enough of kinds and amounts of data that can be used for establishing a TLV of a new substance. But industry has the solb responsibility to develop data on its own products; government is not in a position to develop enough facilities to handle the problem in total, nor should it, when reli able toxicologic consultants are now avail able. ---- -------- _ 'Hie record clearly shows this.1 I made a review of the situation in 1965 and found that in all American chemical industry only seven companies have made significant con tributions to basic data for TLVs of new substances. Of these seven, only two made major contributions; one company made what might be considered a significant but modest contribution, and four made only minor contributions. This is a pathetic situ ation when one realizes the dire need. There is no question that inability to obtain industrial hygiene data is one of the great est problems facing the committee today. Types and Kinds of Data that Industry Can Supply.--Perhaps a glance at the pro cedures used to date to develop TLVs will be helpful in seeing what kinds of data industry can supply to help solve the prob lem of data lack. In Table 1, I have determined the distri bution of the procedures used for TLVs of 414 substances appearing in the 1968 list. It can be seen that industrial plant experi ence (medical surveillance, epidemiologic studies), led the list with 38%. Here is a place that the industrial plant physician can be of real help in supplying data through good medical records, but only if combined with simultaneously obtained er vironmental data. But note this type c plant data is most advantageous in valida ing a limit already set--rarely are the wor conditions sufficiently stable to furnish dat to initiate a limit. (A few notable excej tions are butyl alcohol, acetone, and merci ry.) Here the Industrial Hygiene Found* tion's Repository of Anonymous Data ca be of help; it is questionable whether an TLVs will result from the AMA registry. Human volunteer exposures (line 2, T; ble 1) are becoming increasingly popular < late. They are invaluable for arriving at a estimate of sensory (organoleptic) r sponses, irritants and narcoeis-produdr agents--substances for which animals ju can't supply the answer. The procedure h lesser application for long-acting cumulath substances. For the fast acting substance irritants et alia, exposures may be brief, matter of a few hours. They should 1 repeated, however, with sufficient frequem to determine whether tolerance of sensith ty is a feature of the exposure. It has be* the experience of the committee that TL' of irritants et alia, based on single hum exposures, all too commonly result in f too severe limits. The third listed procedure, chronic at mal inhalation toxicity, represents the a cial procedure about which this report mainly developed. Here is the start in a quiring the basic data from which the TL for new substances stems. This is the cat gory from which the committee most nee data, and which is in the shortest suppl The data are in short supply because indi tries either do not develop long-ter studies, or if they do, more often than n do not see fit to release the data in the op literature. Various reasons are given I this: legal protection of their products, la of staff time to put data in publishal form. Whatever the reason, the data are i forthcoming. Validation of TLVs.--Since its inceptic the TLV Committee has had the policy reviewing annually the listed values; if a information coming to the attention of 1 committee indicated the need for chan such changes were proposed in a sepan tentative listing. Here they remain for period of at least two years before be Arch Environ Health--Vol 19, Aug 1969 leously obtained ennote this type of tntageous in validat -rarely are the work table to furnish data few notable excepacetone, and mercual Hygiene Foundanonymous Data can ionable whether any he AMA registry, posures (line 2, Tareasingly popular of >le for arriving at an (organoleptic) rel narcosis-producing which animals just r. The procedure has ng-acting cumulative st acting substances, ures may be brief, a rs. They should bo `ficient frequency ance of sensitivi-...^osure. It has been :ommittee that TLVs sed on single human imonly result in far ocedure, chronic anij, represents the cruwhich this report is re is the start in acfrom which the TLV ms. This is the cateommittee most needs the shortest -apply, supply because mdus- develop long-term more often than not ? the data in the open asons are given for >f their products, lack data in publishable ason, the data are not .--Since its inception, nas had the policy of 3 listed values; if new y +*>e attention of the leed for change, jed in a separate e they remain for a o years before being OCCUPATIONAL EXPOSURE--STOKINGER placed in the recommended list. Since 1963, deeper scrutiny has been made into the suitability of the limits. The list of sub stances that have been given or are being given special and rather extensive scrutiny is shown in Table 2. Procedures used by the committee take three forms: (1) The chairman and mem bers of the appropriate subcommittee hold a meeting with industry's physicians and in dustrial hygienists and review their experi ence. This procedure is used where the data has not been assembled or published. This procedure has been used for the TLVs for the chromate industry and the nitroglycols. (2) Where the data or reports have been published, these are reviewed by the chair man and the committee and the action tak en is that mutually agreed upon by industry and American Conference of Governmental Industrial Hygienists by letter correspond ence. This procedure has been used for be ryllium, quartz, uranium, and vanadium pentoxide. (3) Active cooperative projects with industry and toxicology and pathology section of the occupational health program. (OHP) are entered into whereby industry supplies the health records or clinical data for review, or active toxicologic research investigations are made by OHP in con junction with clinical and environmental data obtained by industry. Such is being done cooperatively with a large producer of isocyanates to determine means of detecting the hypersusceptible worker, a side bonus of which will be the validation of the TLV for the isocyanates. A similar study is being cooperatively made of carbon disulfide. To give a clearer idea of how these vali dation procedures work, a most productive day's meeting was held with industrial phy sicians and hygienists of the chromate in dustry. The reason for selecting the chro mate industry was that no evidence of the suitability of the TLV for chromic acid or chromates had ever been brought forth for the prevention of either nasal perforation or bronchogenic carcinoma. All environmental levels had exceeded the recommended limit of 0.1 mg/cum when large excesses (29 fold) of lung cancer and nasal perforation were found in 1950, and the health experi ence had not been reviewed in these terms since the industry had improved its control Table 1.--Distribution of Procedures Used to Develop or Validate ACGIH TLVs Through 1968' Procedure No. % Total Industrial (human) experience Human volunteer experiments Animal, inhalation-chronic Animal, inhalation-acute Animal, oral-chronic Animal, oral-acute Analogy 157 45 83 8 18 2 101 38 11 20 2 4.5 0.5 24 For 414 substances exclusive of "Inert" particulates and vapors. Table 2.---Substances Validated for TLV or Undergoing Validation Since 1963 Validated* In Process Beryllium Carbon monoxide Chromates & chromic*acid Cristobalite Nitroglycols Quartz Uranium ? Vanadium pentoxide ? By committee action. Asbestos (all forms) Benzene Carbon disulfide Fibrous glass Isocyanates Tetraethyl lead Tetramethyl lead Petroleum distillates measures to the recommended limit. In brief, the day's discussion revealed that the limit for chromic acid mist was satisfactory in preventing nasal perforation, and in ad dition contained a safety factor of three or four; that the limit was probably satisfacto ry for the prevention of lung cancer, as no new cases have appeared since the reduc tion in exposure occurred, but that the ten years in which the closer controls were op erative are probably too short a time to be certain of its validity in this respect. In a similar meeting with representatives of the dynamite explosives manufacturing industry, a question of an improperly stated TLV for intermittent exposure to ethylene glycol dinitrate and nitroglycerin was re solved to the mutual satisfaction of each of the parties. Statements derived from the long experience of the medical directors of the companies that normally would never get to the attention of the committee were elicited in amicable discussions. In regard to substances in the process of validation, I can mention three--asbestos, carbon disulfide, and isocyanates--that rep resent extensive, cooperative efforts by both industry and the PHS Occupational Health Program, and five substances that represent purely unsolicited efforts of industry to de- Arch Environ Health--Vol 19, Aug 1969 280 OCCUPATIONAL EXPOSURE--STOKINGER velop information on a valid TLV (ben zene, fibrous glass, tetraethyl and tetramethyl lead and petroleum distillates). From these cooperative ventures and the increasing number of voluntary efforts of industry itself to validate some of the more controversial limits, we see an encouraging trend. More and more, industries are de veloping impressive industrial medical de partments. More and more, industries are either establishing their own toxicology lab oratories or purchasing toxicologic studies from a rapidly expanding number of com mercial toxicity testing laboratories. More than 50 of these are available, exclusive of university sources. Not more than a half dozen are presently sufficiently well equipped to do first rate long-term inhala tion studies. Industrial associations, the American Pe troleum Institute, Lead Industries Associa tion, American Welding Association, Auto mobile-Manufacturers' Association, among others, now have large research programs directed toward supplying data in support of safe limits of their sponsors' products. In addition, one can discern among industry's medical departments a keener interest in solving industrial hygiene and toxicology problems. These broadened activities of industry would seem to relieve considerably the problem of data lack mentioned earlier. But closer inspection of the type of data being developed indicates that present efforts are directed to the validation of limits already established; little progress has been made toward a freer access of the committee to information on newly introduced industrial chemicals. This problem the committee still has with it. The Problem of Misinterpretation of TLVs.--Another vexing committee problem arises from the misinterpretation and mis use of the TLVs. Particularly culpable are the factory inspector and the legal profes sion. Their common fault lies in misinter preting the TLVs as fine lines between safe and dangerous concentrations "either it is, or it isn't" phenomenon. Such strict inter pretation is not within the intent expressed in the preface to the TLVs, and places industry in undue jeopardy. Such misinter pretation fails to take into consideration that with few exceptions, the TLV is time-weighted average value which perm excursions above the limit provided equii lent excursions below the limit occur. Tb a single, or even several, concentratic monitored above the limit is not ipso fa< evidence of injury. The reason this is so that the TLV has an inherent safety zo between the limiting value and the con tration capable of producing injury. Despite the fact that such principles ha been clearly stated for many years in t annually issued TLV booklet, they ha been commonly ignored. Recently, howev the development of short-term limits (Per sylvania) ceiling values, and the concept "peak" concentrations (USASI, Z37 Co mittee) introduce into the picture the a cept of variable permissiveness that is compatible with the interpretation of a lir below which all values must fluctuate the prevention of injury. Misapplication and Misuse.--Misund standing on the relationship between TL and short-term exposures has on occasi come to the attention of the committee, attempting to arrive at a short-term comu nity exposure limit for beryllium, the i Force suggested a limit of 750/xg-min/ci for a single exposure. This was presumal derived from Haber's Rule, C x t- K, mg the Atomic Energy Commission-reco mended in-plant limit of 25/xg/cum periods not to exceed 30 minutes. But i permissible Ct value for community erj sures is about 43^g-min/cum. Hence t 750/ig limit is considered dangerously exo sive. In another instance, attempts by t Navy to obtain short-term exposure lim the suggestion was made to multiply i TLV by 10 "across-the-board." 11118 is i considered good practice because some a stances do not follow Haber's rule and hi concentrations for brief periods are ra toxic than equivalent exposures at low o centrations, ie, Ct is not always consta Other Misapplications.--Misuse of i TLVs as a measure of comparative toxic --frequently used by industry's salesmen prove the virtues of their products ove competitor's gives the committee freqo headaches. Use of TLVs for comperat toxicity is permissible only when meta Arch Environ Health--Vol 19, Aug 1969 ;ceptions, the TLV is a rage vaJue which permits the limit provided equivalow the limit occur. Thus, a several, concentrations the limit is not ipso facto . The reason this is so is s an inherent safety zone ng value and the concenproducing injury, that such principles have d for many years in the TLV booklet, they have nored. Recently, however, f short-term limits (Penn/alues, and the concept of tions (USASI, Z37 Cominto the picture the conpermissiveness that is inle interpretation of a limit values must fluctuate for injury. and Misuse.--Misunder?Iationship between TLVs tposures has on occasion of the committee. In .t a short-term commu... for beryllium, the Air i limit of 750/xg-min/curn ure. This was presumably ier's Rule, C x t -- K, usnergy Commission-recomlimit of 25^g/cum for ceed 30 minutes. But the .lue for community expo3/ig-min/cum. Hence the sidered dangerously exces- itance, attempts by the hort-term exposure limits, is made to multiply the ss-the-board." This is not ractice because some sub low Haber's rule and high r brief periods are more ent exposures at low cont is not always constant, ications.--Misuse of the re of comparative toxicity by industry's salesmen to of their products over a 5 the committee frequent )* TLVs for comparative only when metabo- .'9 OCCUPATIONAL EXPOSURE--STOKINGER 281 lism of the compared substances is similar. In most cases, however, either the metabo lisms differ, or they are unknown. In addi tion, the bases of TLVs for different sub stances differ; not all TLVs are based on toxicity. A striking example of the erro neousness of such a comparison is that of hydrogen cyanide (HCN), TLV 20 ppm, with sulfur dioxide (SO*-), TLV, 5 ppm. The TLVs indicate that S02 is more toxic than HCN, which is ostensibly ridiculous! The reason is of course that the TLV for SOo is based not on health effects as is HCN, but on irritation. Future Problems--TLVs vs Community Air Limits.---Perhaps one of the problems of greatest concern in the committee's fu ture is how to reconcile to the satisfaction of chemical labor union leaders, union workers, their wives and families, the often large discrepancies in the TLVs for those substances in industry that are to appear ('and are now appearing) as community air limits. How to explain, for example, that when a community has a limit for lead in air of 5/ig/cum (Pennsylvania) that it is all right for their "boys" to breathe 40 times this amount for their working lifetime in industrial plants? It is doubtful that the rational bases for the differences can be made sufficiently convincing to be generally accepted--any more that the rationale for fluoridation has met with general accept ance. Legalization of Industrial Air Standards. --Although it is particularly difficult in these days of federal reorganizations to be a prophet of "the shape of things to come," it might be worthwhile to try to foresee what problems will exist when the Occupational Health and Safety Act (or some similar act) is made into law. As the act is now written, the Department of Labor (USDL) will set standards for industrial air upon the counsel of an advisory committee. The present Occupational Health Program in the National Center for Urban and Indus trial Health will establish the criteria on which the standards will be based. Because the standards will be "consensus" stand ards, it is probable that neither the recom mendations of the TLV Committee or those of the USASI, Z37 Committee will be given "carte blanche" acceptance. Being consen sus standards, the dominant philosophy and voice of government may be less clear than in the past (the USASI Committee, domi nated by industrial representatives, and whose findings are adopted now by USDL, presently attempts to attain a consensus from the scientific community). What the future problems will be, will be determined largely by how broad a consensus will be required, which in turn will determine the breadth of the advisory committee. Whether the presently constitued TLV and Z37 Committees will continue to function in their present capacity seems to me problem atic. The old problem of data acquisition, however, could be made easier if substantial government funds are made available to the Occupational Health Program to develop industrial hygiene data on a broad basis. Reference 1. Stokinger, H.E.: Industrial Contribution to Threshold Limit Values, Arch Environ Health 10:609 (April) 1965. TEMPO HOPPING Air transportation has highlighted the relationship of circadian rhythms to the subjective and physical well-being of travelers, especially when they rapidly traverse more than four time zones. One country is currently proposing to mend its air crew flight time limitations as follows: "In the event of there being a time zone change of four or more hours between the place of departure and the place where duty ends, the subsequent rest period should be not less than twelve hours."--Mohler, S.R.; Dilie, J.R.; and Gibbons, H.L.: The Time Zone and Circadian Rhythms in Relation to Aircraft Occupants Taking Long-Distance Flights, Amer J Public Health 58:1404-1409 (Aug) 1968. Arch Environ Health--Vol 19, Aug 1969