Document MGq6zKE4MJBzwqkw4QVYkzdJa

FILE NAME Threshold Limit Values TLV DATE 1989 DOC TLV001 DOCUMENT DESCRIPTION Threshold Limit Values - Historical Perspectives and Current Practice Threshold Limit Values Historical Perspectives and Current Practice Grace E. Ziem MD Dr PH and Barry I. Castleman ScD A 1989 Occupational Safety and Health Administration standard mandates that workplace air concentrations be held below new permissible exposure limits for 376 substances As more than 350 of these limits came from the 1987 list of Threshold Limit Values TLVs the medical basis of the TLVS is of direct importance to the health of millions of workers However the TLV development process has been gravely flawed by lack of scientific rigor inadequate medical input and lack of attention to financial conflicts of interest The adoption by the Occupational Safety and Health Administration of many poorly supported values as permissible ex- posure limits reflects also the underutilization of industrial medicine in identifying health effects of exposures below the TLVs It is thus the responsibility of the medical profession to act on the presumption that the TLV permissible exposure limits are unsafe limits until a sound underlying body of medical and scientific literature exists for the substances on the list If is industry s responsibility to commit itself seriously to medical and exposure monitoring and to begin to remedy the knowledge deficit that exists about the less immediate health effects of most industrial materials efore reviewing the subject of occupational exposure Before certain basic issues bear mention First the medical profession has a fundamental importance in the investigation and evaluation of the harmful effects of industrial materials Second the necessary medical resources need to be provided by industry to make possible the medical surveillance and care of workers exposed Third there is a need to develop and train the profes- From 3511 Moultree Place Raltimore MD 21236 Dr Ziem Occupational Health Physician and 1722 Linden Ave Baltimore MD 21217 Dr Gastleman Environmental Consultant Address corre- Apondence to Dr Ziem This work was presented at the American Conference Boston Mass May 5. 1989 Occupational Health 00916-1736 00916-1736 89.3111-0910 02.00 02.00 Copyright by American College of Occupational Medicine 910 sional resources to meet the needs of the millions of places of employment The adoption of standards with specified numerical exposure limits accomplishes nothing unless the necessary professional resources are provided to gather and evaluate information on exposures and health effects The Occupational Safety and Health Administration OSHA Standard for Air Contaminants In the closing days of the Reagan Administration OSHA adopted new permissible exposure limits for 376 substances Virtually all of these limits came from the 1987 list of Threshold Limit Values TLVs published by the American Conference of Governmental Industrial Hygienists Industry is required to be in compliance by September 1989 In developing this standard OSHA disregarded rec- ommendations by the National Institute for Occupational Safety and Health NIOSH for stricter limits for 68 specific substances The idea of adopting the TLVs had been suggested in 1983 by the Synthetic Organic Chemical Manufacturers Association and the chemical industry's response to this OSHA rulemaking was unusually favorable C.B. Mackerron Chemical Week Jan- uary 25 1989. and comment from the Dow Chemical Company on OSHA's proposed air contaminants rule July 1988 The AFL and at least 16 industrial parties have gone to court over the standard OSHA has recently announced that it is considering additionally requiring medical monitoring and air monitoring in industries where regulated substances are used Physicians in industry have good cause therefore to wonder how protective the new limits are In fact the scientific quality of the process for developing the TLVs has been critically examined and evidence of corporate influence in developing the TLVs has figured in the Threshold Limit Values & Castleman debate over the new OSHA rule A paper on these issues published in May 1988. has engendered a lively discussion including more than 20 commentaries by the end 2 of 1988 in the American Journal of Industrial Medicine The purpose of this paper is to summarize the critique of the TLVs referring to data already published as well as presenting information gathered since OSHA proposed its new rule in 1988 The material here will be addressed primarily to physicians in industry The story begins by recounting how the medical responsibility of relating working conditions and health was in large part assumed by a group of industrial hygienists the American Conference of Government Industrial Hygienists ACGIH Origins of the TLVS ACGIH traces its history as a professional organiza- tion back to 1938 An ACGIH committee compiled a listing of state government exposure limits for various chemicals in 1942 In 1946 ACGIH published its first annual list of recommended Maximum Allowable Con- centrations MACS for 144 substances The primary sources for this were ACGIH s 1942 compilation and a 1945 paper by industrial hygienist Warren Cook It is interesting to recall what was said of the safety of these limits at the time in view of later developments ACGIH said in 1942. The table is not to be construed as recommended safe concentrations As to underline that point the text went on to say The material is presented without comment Cook whose paper sup- plied 118 of the exposure limits adopted emphasized that his intent was to provide a handy yardstick to be used as guidance for the routine control of these health hazards that compliance with the figures listed would guarantee protection against ill health Cook went on to advise that maintenance of the limits he suggested should not be considered a substitute for * medical monitoring By 1946. most state governments had industrial health units and so did some cities and counties The MAC values reported by 27 of these agencies were quite variable for some chemicals For butanol the limits varied from 25 to 300 ppm in air depending on where the workplace was located For turpentine the range was 100 to 700 ppm for methanol from 100 to 300 ppm for nitrobenzene 1 to 5 ppm On the other hand there was substantial agreement f for many other chemicals among the health agencies Up to this time MACs in use had on the whole caused no serious handicap to industry according to JJ Bloomfield one of the leading industrial hygienists ' of the US Public Health Service However there was desire among the government people to harmonize their MACS and thus avoid the health and economic impacts of having divergent conditions for industry ACGIH acknowledged in 1946 that no uniform defi- nition of MACs existed citing three concepts then in use no safety margin against known health effects some safety margin against health effects and protection from objectionable but not harmful concentrations AC- GIH initially declined to define what its MACs were or to state whether they were limits not to be exceeded for 30 minutes 1 the MAC for hour 8 hours or longer For example chlorine was 5 ppm which compared unfavorably with 4 ppm recommended by Henderson and Haggard for minute to hour exposure periods the 100 ppm MAC for carbon monoxide had been rec- ommended by Henderson and Haggard for 1 hours several The 1947 list included 155 MACs The chairman of the Committee on Threshold Limits chemist LT Fair- hall expressed great confidence that the industrial hygienist was well placed to set health standards He is in contact with the individuals exposed and therefore soon learns whether the concentrations measured are causing any injury or complaint ? Up to this point the man TLV committee still did not include one phy- sician member In 1948 the MACS were renamed Threshold Limit Values Despite the very different emphasis of this new nomenclature the term TLV was not defined at the time of its introduction The TLV committee noted that People vary greatly in their response to drugs toxic substances To this irremovable obstacle and was added the acknowledged difficulty of trying to protect the worker while not imposing an a on the manufacturer impossible burden In 1953 a preface was added wherein the TLVs were described as maximum average concentrations of con- taminants to which workers may be exposed for an 8 hour working day day after day +10 health Both the term used and without injury to its definit.on now promoted the TLVs as hazard thresholds for exposure to chemical and mineral substances many of which were known to have serious irreversible effects The TLV committee now sought to offer a guarantee where Cook had explicitly said no guarantee was war- ranted Most of the exposure limits on the list were the 5 same values recommended in 1945 by Cook Despite the accompanying preface assertion that the TLVs were based on the best available information there is no evidence that any review was done or new rationale offered to justify this sweeping disregard for the uncer tainties underlying the TLVs The TLV committee chairman industrial hygienist Alan Coleman used more qualified language at the ACGIH meeting of 1954 He described the TLV as the concentration of a substance that should cause / significant injury to the health of the large majority of 1 persons exposed daily The committee ifself tempered its description in 1958 TLVs represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect5-12 Precisely because the TLV committee had taken a very difficult technical political and economic problem off the shoulders of state and local agencies the TLVs were uncritically welcomed as uniform limits across the country State and local agencies reduced their propor- tional employment of medical personnel and stopped issuing MACs on their own in the early all but , 1950s Journal of Occupational Medicine 31 No. November 1989 911 As it became clear that the state and local officials on the TLV committee were not issuing terribly burdensome limits for their local plants to meet industry adjusted to this state of affairs without protest Meanwhile the commercialization of new chemicals by industry far outstripped the capabilities of a volunteer committee to keep up As new chemicals were widely introduced by the hundreds the TLV committee struggled to add to its list less than 10 per year Revisions of the TLVs once listed were fewer still and is evident that after the first few years the primary focus of the TLV committee was on expanding the list Until 1962 this responsibility was handled by a committee of only four to eight people Many pitfalls of reliance on the TLVs had been anticipated from the time they were launched W.P. Yant first President of the American Industrial Hygiene Association told members of the Industrial Hygiene Foun- dation that monitored average concentrations of air contaminants would not take account of several factors peak exposures that could be very harmful synergistic effects of multiple exposures and the great increases in respiration rates arising from high levels of physical 14 activity and work in hot environments Yant also observed that lists of limits gain prestige ~ and authority through mere copying and repetition He warned that mandatory requirements which the TLVs were clearly destined to become were usually minimum requirements . permissible conditions representative of the worst Such requirements he said could stifle progress and freeze endeavor at the estab- 4 ushed minimum Yant's apprehensions proved well founded as the TLV committee fell further behind in its efforts to keep pace with innovation As the list of TLVs grew longer more of the limits would tend to be based on reviews and information not updated for years British authorities criticized American practice for its heavy emphasis on measurement and reliance on reference limits Noting that TLVs were almost always amended in the downward direction reducing the con- centration formerly accepted as safe United Kingdom factory inspector Bryan Harvey preferred to call them " theoretically allowable maximum concentrations Medical Inspector of Factories AIG McLaughlin derided the very idea of threshold limits as reflecting " an assumption that man is a standardised machine The indoctrination of American industry and profession- als with a preoccupation with taking samples and de- signing controls to meet reference exposure limits was in turn seen as the basis of another serious shortcoming a peculiarly American tendency to consider substitution of dangerous materials as the last line of approach to 15 health hazard control instead of the first Industrial physicians in the United States were also dismayed al the growing acceptance of the TLVs issued by a committee dominated by industrial hygiene engineers chemists and toxicologists Initially not a single physician was on the TLV committee at most physicians comprised only a small minority of the committee members Never had the chairman of the TLV committee been a physician this would not happen until 1985 At a 1952 meeting of leaders of the Industrial Medical 912 Association clinician Frank Princ said ost of the TLVs are picked out of a hat 95 percent are on the basis of animal experiments only incorporated into state codes and we are faced with ridiculous standards Is there a doctor among the group that puts out these standards17 After all what industrial hygienist sees the workers health status the way the plant doctor does What toxicologist is intimate enough with his rats to learn whether they feel pain or are suffering from reduced mental acuity What did these government engineers chemists and toxicologists read or know of the medical literature even just what is imparted in JAMA or the Lancet It would have been malpractice if a council of doctors had prescribed such a list of exposures as approved for consumption by all the workers in the coun- try ACGIH nonetheless went on to make the essentially medical evaluations on which new TLVs were based The industrial physicians group did not undertake the task of either publicly criticizing the TLVs or proposing its own workplace exposure limits Only occasionally did individual industrial physicians pass on information to the TLV committee through the 1950s and 1960s Led by toxicologist Herbert Stokinger of the Public Health Service the TLV committee expanded its membership and output in the early 1960s ACGIH also published for the first time a volume entitled Documen tation of Threshold Limit Values where the basis for about 250 TLVs was stated with references in the space of 112 pages Stokinger approached the Manufacturing Chemists Association now Chemical Manufacturers Association for increased input from member firms starting in 1964 This met with limited response The companies had no statutory duty to disclose new knowledge about chemicals used in general industry before the passage of the Toxic Substances Control Act in 1976 In the years before the Occupational Safety and Health Act 1970 regulation of workplace health hazards by the states was minimal and manufacturers were about the on's parties capable of knowing what the exposures were in their plants and whether there were adverse medica consequences ACGIH'ACGsIH's annually republished claim that the TLVs > were based on the best available information thus sidestepped the reality that the TLV committee was left begging for data A committee of the Industrial Medical Association acknowledged that unpublished data was in the possession of companies that could ** contribute to the establishment of realistic TLVs Corporate Influence on the TLVS The recommendations of corporate officials and con- sultants were given great weight by TLV Chairman Stokinger Massachusetts health official and longume TLV committee member Hervey Elkins complained in a letter to fellow committee member William Frederick in 1966 It annoys me no end that any action that could possibly adversely affect a certain chemical company is Threshold Limit Values & Castleman immediately objected to by a consultant to said company " and the objection is always accepted by the Chairman The companies themselves individually and under the auspices of such groups as the Industrial Hygiene Foun- dation also had periodic meetings with members of the TLV committee and communicated their concerns both orally and in writing Just as some corporate communications to the TLV committee delayed or prevented action other unpub lished information was accepted as the basis for setting TLVS The growing reliance on unpublished corporate communications some of which were phone calls and most of which do not survive in written form today is 2 20 reflected in the Documentation By 1986 unpublished corporate communications were important in supporting TLVs for 104 substances out of less than 600 listed in the Documentation 5th ed For twenty of these key communications from corporate employees out of 104 the corporate affiliations of the correspondents were not stated in the Documentation Of the 104. the 37 cases of unpublished industrial experience reflect a pattern of uncritical acceptance of assertions from financially interested parties based on scant data of poor quality These assertions absent explanations of materials and methods used would never be accepted for publication in medical or other scientific literature Moreover they include many eval- uations of a medical nature that were reported by 2.20 2.20 industrial hygienists and other nonphysicians Some had expected that the story of the TLVs would have ended with the adoption by OSHA of most of the 1968 TLVs as its first set of exposure limits Congress established and funded NIOSH for purposes of conduct- ing research and making recommendations to OSHA for health standards But the TLV committee not only re- mained as active as ever after 1970. it even permitted time employees of chemical companies to become centrally involved in the development of the TLVS The participation of industry representatives on the TLV committee began with the addition of Dow toxicologists VK Rowe and Theodore Torkelson as liason members in 1970 These men were assigned responsibility for developing documentations on which new or revised TLVs would be based The chemicals assigned to them initially were all Dow products 2,4,5 vinyl chloride ethylene glycol methyl bromide and propylene glycol methyl ether No objection was evidently made over the fact that many of the chemicals assigned to these employees of Dow and industrial hygienist James Morgan of DuPont starting in 1972 were products marketed by the firms that employed them The chemical assignments of these individuals were regularly re- corded in the minutes of the TLV committee although publicly it was stated that these consultants actually vote on adoption of TLVs did not Perhaps because the corporate representatives were paid for their work on the TLV committee and provided with the ample resources and support of their employ- ers the they were among the most active contributors to TLVs TLV committee minutes and other records show that Torkelson individually and as chairman of key subcommittees was assigned at least 30 of Dow's halogenated solvents pesticides and other industrial chemical products between 1970 and 1988 since 1977 including perchloroethylene trichloroethylene 1 3dichloropropene divinylbenzenes carbon tetrachloride chlorine propylene dichloride ethylene diamine meth- ylene chloride and acrylamide Similarly Morgan and his successor Gerald Kennedy of DuPont obtained the task of documenting many DuPont pesticides chloro- fluorocarbons and other products since 1977 including hydrogen cyanide acrylonitrile hexafluoroacetone p nitrochlorobenzene trichlorotrifluoroethane 2 methyformamide Dr Georg Kimmerle has been listed in TLV and di booklets since 1981 simply as German MAK Commission liason He is a physician employed by the German chemical producer Bayer whose US subsidiary Mobay makes pesticides isocyanates and other chemicals Shortly after joining the TLV committee Kimmerle was pri marily responsible for the decision to double the TLV for one Mobay pesticide fenthion He then drafted documentations for new TLVs for three other pesticides made in the US solely by Mobay fenamiphos metribu- z~-nand sulprofos The other five chemicals recorded as assigned to Kimmerle amitrole thiram xylidine perchloromethyl mercaptan and phenylene diamine are produced by Bayer in West Germany Kimmerle's handling of TLV committee work unlike his duties with the German MAK Maximum Workplace Concentration Commission were not required to be handled as a con- fidential separate matter from his job at Bayer In all corporate representatives were given primary responsibility for developing TLVs on more than 100 substances between 1970 and 1988. including at least 36 classified as carcinogens by official bodies Complete information on the chemical assignments is not even available from ACGIH) There is no question that the economic impact of the TLVs on the chemical industry generally and on Dow DuPont and Bayer in particular has been enormous There seems no reason to doubt that chemical industry employees working on the TLV committee were implementing corporate policies of their firms This view is consistent with Dow's recommenda- tions to OSHA to adopt the TLVs instead of stricter NIOSH recommendations for seven Dow products at least six of which had been handled by Torkelson on the 5 TLV committee Industry employees aside practically nothing has been disclosed about the documentations assigned to committee members who had time consulting relationships with chemical producers ACGIH has never required members of the TLV committee who do corporate consulting to either disclose these business connections or excuse themselves from development of TLVs on chemicals of importance to their clients The TLV booklets have listed such persons only by affiliations they had with universities TLV committee minutes flectingly mention meetings of the committee and its subcommittees with dozens of representatives of companies and trade associations Nothing in writing relating to most if not all of these meetings is in the chemical files at ACGIH Robert Spirtas a member of the committee since 1981 wrote Journal of Occupational Medicine 31 No. November 1989 913 of his impression of these encounters in a 1987 letter to TLV Chairman E Mastromatteo Presentations by outside groups have in my experience always been allied with the management point of view The majority of the presentations have been personal interpretations of the published literature In my opinion these presentations have been attempts to lobby the committee with very little new data This state of affairs led ACGIH Treasurer Philip Bierbaum to urge in 1988 memorandum to the ACGIH Board that no presentations by outside groups to committee members be allowed unless they are publicly announced and open to the public As of late 1988 the TLV committee would not even permit interested scientists to attend its meetings as observers Only after OSHA had proposed to adopt hundreds of the TLVs in 1988 did ACGIH allow re- searchers to examine relevant ACGIH files eg recent TLV committee minutes The TLV committee has stoutly refused to publicly disclose members paid sources of corporate consulting work This might be extensive as the present member committee includes only six time government employees The TLV committee has also resisted recommendations by its only labor representative and members of the ACGIH Board that industry employee memhers of the committee be precluded from drafting TLV documentations Although some reforms may finally be instituted in 1989 the many TLVs just adopted as OSHA standards are a legacy of an earlier era Former NIOSH director John Finklea has remarked that the TLVs were the result of a process that would currently be viewed as seriously flawed Medical Inadequacy of the TLVS The information base upon which the TLVs were developed was severely limited For standards intended for a potential lifetime of exposure chronic data are critical However for at least 90 of the TLV chemicals sufficient data on term effects are unavailable either from animal studies or studies of industrial work- ers with term exposure to known concentrations of the substances The very concept of a daily average exposure limit has been attacked as being inconsistent with what is known about toxicity and evidently originating more 24 from economic than scientific considerations Ath- erley's analysis concluded that the weighted aver- age index cannot be viewed as a scientific idea under- pinned by either empirical evidence or plausible scientific hypothesis 24 In view of this the TLV committee's deletion in 1984 to 1986 of most of the short exposure limits was particularly harmful STELs for nearly 200 substances were dropped prior to OSHA'S adoption of the TLVS ) The TLV committee's heavy reliance on animal data mostly acute and subacute toxicity studies raises a number of unavoidable problems One cannot elicit a medical history from an animal and symptom data can be missed that could be severe enough in a human to 914 interfere with productive function at work In addition the animal data gathered were very limited in scope as well as duration Typically no study was done of neurologic and neurobehavioral function beyond meager observations of animal behavior such as lethargy fight- ing etc Thus animal studies are unable to evaluate cognitive changes such as we now know can occur from exposure to many solvents and other chemicals Animal studies also have not included an evaluation for pulmonary function despite the fact that many chemicals are irritants and chemical allergens and repeated exposure to such agents could well reduce pulmonary function nor was immunologic function evaluated for the vast majority of chemicals Endocrine function was at best evaluated by an occasional blood glucose test typically ignoring the potential for endo- crine alterations in other organs Animal studies often did include information on the appearance of many but not all organs at death by gross and light microscopic analysis However useful structural information 19 though it is not a substitute for evaluating the function of organs Another shortcoming of the TLVs was the frequent failure to use information that was available For ex ample no systematic literature search was done in preparing documentations on hundreds of chemicals References used are often very dated and more recent information is often missing Information in the international medical literature does not appear to have been reviewed for the vast majority of chemicals In fact little reference is made to the basic US medical literature in the TLV documentation Thus contrary to the TLV booklet's persistent claim the TLVs are not based on the best available information The medical inadequacy of the TLVS is evident from a review of four occupational medicine journals since the start of 1987 Table From this limited sampling it would appear that further evidence of harm at and below the TLVs appears in the literature almost monthly This review did not include industrial hygiene toxicology and general medical journals Other scientists are encouraged to review these for TLV effects The development of TLVs and evaluation of relevant scientific literature have mainly been done by industrial hygienists and other nonphysicians Although industrial hygienists are vital to developing control strategies for chemicals most lack training in the biomedical sciences to interpret health effects data reliably and independently Yet this is exactly what they had to do as volunteers on the TLV committee Copies of reviewed articles were generally not provided to the entire committee the sole responsibility for accurate interpretation of the articles typically fell to the committee member assigned each chemical The result was a list of exposure limits produced almost entirely by hygienists chemists and toxicologists most of whom lacked the necessary train- ing let alone clinical experience with humans Toxic Torts and the TLVS It is ironic that doctors may now be asked to confer legitimacy on the TLVs Threshold Limit Values & Castleman TABLE Health Effects at and below the TLVS Substance Effects Exposure TLV Aet Acetone Benzene Beryllium Cadmium Ethoxyethanol and Methoxyethanol Ethylene diamine Ethylene oxide Formaldehyde Glutaraldehyde Lead inaphthenate Manganese dust inorganic Mercury vapor Methyl chloroform 1 1 trichloroethane Oil mist Silica minerai Styrene Sulfur dioxide Sulfuric acid mist Toluene Toluene diisocyanate Triethylamine Zinc oxide fume Neurobehavioral performance effects after h at 250 ppm Bone marrow changes leukemia at or below 1 ppm Respiratory sensitization below 2 m Changes in renal function at 0007-0 0007-0 039 mg Changes in renal function at 0 003 mg Changes in renal function at cumulative exposures equal to 20-22 yr at 005 mg Lowered sperm counts and reduced red and white granulocytes blood cell counts at combined expo- sure to 99 99 mg EE and 26 26 mg ME Respiratory sensitization at 1-10 ppm Increase in sister chromatid exchanges in lympho- cytes at 0 35 ppm Respiratory cancer allowing for 10 yr latency 0 1-1 ppm Pathologic changes in nasal mucosa at 0 1-1 1 m Increased respiratory symptoms and headache below 0.04 0.04 mg Blood lead concentrations over 60 dL mean ZPPT of 265 g at 96 m Fatigue trembling tinnitus irritability at 1 mg EEG changes at 25 m Behavioral performance deficits with h at 175 ppm and 350 ppm Decreased DNA concentrations in the brains of ger- bits after continuous exposure to 70 ppm for 3 mos Cross decline in sec FEV at 0 2 mg Lung scarring in bricklayers exposed to dust 21 % free silica 0 5-20 5-20 mg Occupational asthma at 62 7 mg Bronchoconstriction among asthmatics after 3-5 min at 5 ppm Laryngeal cancer at 0 2 mg Neurobehavioral effects in rats exposed 20 min to 125 ppm Impairment in human performance after 6-65 6-65 h at 100 ppm Increased fatigue short memory changes re- duced concentration at 11 5 ppm and 41 8 ppm Neurobehavioral changes visual vigilance after h at 100 ppm Asthma developed within 1 yr in 9 workers at 0 002 ppm Blue haze foggy vision corneal edema eye irritation at 18 mg Lung function changes in guinea pigs exposed 3 h on 6 consecutive days to 5 mg 750 ppm 10 ppm 2...g 2...g 0.05 0.05 mg 19 mg EE 16 mg ME 10 ppm 1 ppm 1 ppm 1.5 1.5 mg 0 7 mg 150 m 5 mg 50 m 350 ppm 5 mg mg 215 mg 5 ppm 1 mg 100 ppm ppm 150 0.005 0.005 ppm 40 mg 5 mg 25 26 27 28 29 30 31 32 33 33 35 36 85 % 8 972 972 972 43 39 45 97 47 48 49 50 51 52 53 54 55 * This table was compiled from review of the contents of 33 months January 1987 to September 1989 of 4 journals Journal of Occupational Medicine American Journal of Industrial Medicine Scandinavian Journal of Work Environment and Health and British Journal of Industrial Medicine ZPP Zinc protoporphyrin * Short exposure limit An increasing number of persons are appearing before the courts with conditions medically attributed to chemical exposures The courts are interested in knowing the state of medical knowledge when these people's exposures to chemical products and wastes occurred A rationale often used to parry charges of negligence and assessment of liability is known as the TLV defense This amounts to We thought that the exposures here would be below the TLVs and we also thought the TLVS were safe so what happened is not our fault But although those in other professions may say we thought the TLVs were safe and sound it is the opinion of the medical profession ie not the medical opinion of the industrial hygiene profession that is most often sought to test such claims today Consequently doctors may be asked to appraise the TLV for one or more chemicals the TLVs in general and possibly even the TLV committee too is hard enough to look back on the withholding of medical expertise and medical knowledge that left so much to the TLV committee for so long But it is professionally humiliating when doctors are asked to Journal of Occupational Medicine 31 No. November 1989 915 dignily the medical stature and safety of guidelines that Alte never really a product of industrial medicme vers detending chemical liability cases may find that the TLV defense is easier for them to raise in an opening argument than is to support with credible medical testimony Alternatives to the TLVS There is an urgent need to compile the information that is available but has been ignored in the TLV development process For example the New Jersey Department of Health recently utilized chronic health effects data from the Environmental Protection Agency known as the Integrated Risk Information System IRIS data base Workday air concentrations were calculated for noncarcinogens and carcinogens report- edly corresponding to no risk of chronic health effects or for carcinogens a million lifetime risk of cancer The resulting exposure limits even for noncarcinogens were markedly lower than the TLVs not infrequently by 3 or more orders of magnitude R Zagraniski 1988 testimony of the NJ Department of Health at informal hearings on OSHA's proposal to update permissible exposure limits for toxic substances IRIS data exist on many more chemicals and could be used to supplement our understanding Further use needs to be made of the international iterature particularly the industrialized countries Much information on chemical effects is available in English from the Scandanavian countries In addition the Soviet Union has exposure limits on more than 1400 chemicals These limits were reportedly developed to prevent physiologic alteration not just clinical disease Critics of the Soviet exposure limits have sometimes raised a separate presumption that the Soviets in prac- tice follow less stringent limits But the medical issue is not the state of Soviet engineering practice Physicians need to have as many data as possible on term effects of chemicals to understand what levels could cause harm Philosophic and political differences have not prevented scientific cooperation in other healthrelated areas and international relations now offer hope tor expanded USSR contact on matters of impor tance in industrial medicine Exposed workers themselves are a potentially vast source of data The US experience in occupational health is that medical and environmental monitoring that is nut legally required is often not conducted We are thus missing an enormous amount of potentially useful effects data on early functional changes in work- ers OSHA's expected medical and air monitoring stand- ards may soon help stimulate industry to generate this response data However doctors should not wait tor legally mandated monitoring medical evaluations for potential to begin to conduct health effects below the TLVS Industry needs to provide adequate resources to allow physicians to visit workplace areas regularly regularly to monitor all exposed workers medically and to update their knowledge about toxicologic effects regularly Doctors 916 need adequate computer and other literature access for all substances used released and produced in the work- place Doctors also need to be provided with sufficient time " to do a thorough review of systems Experience has shown that a great deal of knowledge on chemical health hazards is not in the books and clusters of adverse effects can be clinically identified sometimes before one of our busy medical colleagues has gotten the problem into print Clinical cases are frequently the first evi dence of occupational disease phenomena and the patients themselves are an indispensable source of information With the deficiency of published literature on the chronic effects of most chemicals in use the need for doctors to take the time to listen to patients is underscored Occupational medicine is a demanding field and a full evaluation ofa single person with illness potentially related to chemical exposure can take sev- eral hours Much better use can be made of industrial nurses especially in the first to small plants where it is nurses who are see problems and hear workers health complaints Industrial nurses and physician assistants working with physicians are capable of playing a more sophisticated role in occupational disease assessment than they have been offered in the past To be most effective however these professionals will need to de- velop additional skills in occupational disease recognition For example they will require further training regarding the toxic effects of chemicals taking medical and occupational exposure histories and conducting physical examinations Their preliminary assessments can then be useful in a team approach working with the physician Industrial hygienists can expand their reconnaisance capability far beyond the generation of numbers on exposure levels Industrial hygienists as well as nurses and worker health and safety representatives need specific training on the toxic effects of chemicals on the body and on how to interview workers for health effects in the intervals between medical monitoring These health effects interviews although not a substitute f^r medical evaluation can nonetheless assist in the early detection of effects from irritants sensitizers and nerv ous system toxins The New Jersey Department of Health is developing a Guide to Workplace Inspection that could facilitate this process That agency's Hazardous Substance Fact Sheets now available for about 1000 chemicals includi target toxicity information that can help to focus workplace health effects interviews Because the TLVs lack scientific validity the role ul air monitoring should be a concentration should never different be relied one A specific air upon as indicating safety Rather air monitoring should be used to assess the effectiveness of controls In addition because at this time there are no known safe exposure levels physicians as part of the management team should insist on controls that reduce all exposures to the maximum extent techmically feasible To advocate a lesser degree of protection would violate the dictum to do no harmn Threshold Limit Values & Castleman Similarly workplace inspectors may be better off not using the TLV booklet as now written because of the misleading assertions stated in its preface These inaccurate claims based on the best available informaLion nearly all workers may be repeatedly exposed day after day without adverse effect provide a false sense of security to nonmedical personnel Unless such claims are deleted from TLV booklets industrial phys~-cians would be prudent to instead obtain or encourage development of other sources of information Despite laws and regulations giving workers the right to know most hazard communication training programs are general and prepackaged and do not address the specific toxic effects of the substances used in the workplace If workers are not properly informed about such dangers they will not be prepared to alert the medical department when early symptoms develop Industrial physicians should ensure that all hazard communication training fulfills the legal requirement to include hazards of the specific chemicals used The New Jersey Hazardous Substance Factsheets are particularly useful in this regard as they discuss early symptoms and effects in lay English that the worker and supervisor can understand Of course it is primarily industry's responsibility to provide and encourage adequate coordinated occupational health programs Just as management provides engineers with flow charts to monitor the industrial process doctors need to be informed about the materials used and created in every department It is management's responsibility to encourage cooperation between health professionals to provide the resources and a framework for monitoring exposures and health of workers and to grant industrial physicians the authority to fulfill their professional obligations to the people at work Industrial physicians will not be able to do their job well unless and until industry respects the impor- tance of industrial medicine and makes the commitment to prevent not ignore occupational diseases The judgment of how much exposure can cause disease in humans is ultimately a medical decision Industrial physicians as a profession and through the American College of Occupational Medicine have the obligation to step forward and assert their responsibilities in assessing health hazards in industry In fact to not do so could be viewed as malpractice by some Workers have been ill served by having critical decisions about their health delegated to engineers carrying TLV booklets References 1 Air conturunants final rule Federal Register January 19 1989 54 2332-2983 @ Castleman BI Ziem GE Corporate influence on threshold limit ales Am Ind Med 1988 13 531 559 3 Report of the Subcommittee on Threshold Limits Transactions the 5th Annual Meeting of the National Conference of Governmental Industrial Hygienists 1942 163-170 4 Report of the Subcommittee on Threshold Limits Proceedings of the 8th Annual Meeting of the American Conference of Governmen- tal Industrial Hygienists 1946 54 55 5 Cook WA Maximum allowable concentrations of industrial atmospheric contaminants Ind Med 1945 936 946 6 Bloomfield JJ Codes for the prevention and control of occupa tional diseases Industrial Hygiene Foundation Transactions Bulletin No 6. Eleventh Annual Meeting 1946 71-79 71-79 7 Henderson Y. 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