Document Sample

          ~ M-7lolume 35, Number 12, December 1993
            .~~ . .- .
            : . .,r.
                                                                                                   and a range of 0 to 8% adenomas and 0
          'Letters to the Editor                                                                   to 6% carcinomas.
                                                                                                     In the multidose study rats (but not
          ~CUders are invited to submit letters for publication in this department . Submit them   hamsters) also were exposed to RCF l .
                                           t' tona e            POB 370 B M ,
                             ourna! f Occupa 1Md'' tcme, ox , ry n awrPA
                                    o                                                              Concentrations used were 50% of the
                  Letters should be typewritten and double spaced and should be designated         MTD (16 mg/m'), and two lower doses
                    (ieation."                                                                     that were multiples of the projected oc-
                                                                                                   cupational and environmental exposure
          Synthetic Mineral Fibers*                   total lung tumor incidence of 13 .0% .       levels (9 and 3 mg/m3) . An air control
                                                      Air controls had 1 .5, 0, and 1 .5% ade-     group was also evaluated, but the chry-
          To the Editor: We applaud the efforts of    noma, carcinoma, and total lung tumor        sotile asbestos control group was not
          Bunn et al' to avoid the errors of omis-    rates, respectively . Chrysotile asbestos    repeated in this study .
         sion that occurred with asbestos by re-      controls had 10 .1, 8 .7, and 18 .5% ade-       In presenting the results of this study,
         porting interim and final data from on-      noma, carcinoma and total lung tumor         Bunn et al listed the results of the RCF
         going studies of animals exposed to syn-     rates, respectively. Bunn et al also cited   I MTD study for comparison and con-
         thetic mineral fibers (SMF) . However,       an average historical control total lung     cluded that the MTD study results (total
         we would like to comment on what we          tumor rate of 2 .9% in Fischer 344 rats      lung tumor rate = 13%) were the only
         believe to be errors of omission and
         interpretation in this article .
             Bunn et al report the results of Ther-
         mal Insulation Manufacturers Associa-
         tion (TIMA}sponsored multidose in-
         halation studies of fiberglass, mineral
         wool, and refractory ceramic fibers
         (RCF), which used rats as the experi-
         mental model. In the fiberglass study,                  Looking for a career change with a future?
         according to the authors, no significant
                                                              EG&G Idaho, Inc., the prime operating contractor for the U .S .
         increase in pulmonary tumors or me-
                                                              Departmentof Energyatthe Idaho National Engineering Laboratory
         sotheliomas was observed . They con-
                                                              (INEL), has an immediate opening for an Occupational Physician
         clude, based on these finding and others,            on the staff of the INEL's Occupational Medical Program (OMP) . The
         that ". . . animal inhalation studies have           OMP provides occupational medical services to DOE and its contractors
         failed to find an empirical relationship             at the INEL, involving approximately 10,000 employees .
         between fiberglass exposure and dis-
         ease." We believe that the definitive an-            QUALIFICATIONS : MD P                         if meeting the licensing
         imal study on fiberglass has not been                requirements of the St % `' r,             - d certification in occupa-
         done and, therefore, that the authors'               tionaUaerospace medlca <<: ~ r i dicine, internal medicine,
         conclusion is premature .                            or family practice is des~

             The TIMA studies were designed sub-              RESPONSIBILITIES : P : 1al medical services to
         sequent to the evaluation of other                                                             -
                                                              INEL employees pre j ._?-- ~ - iodic physical examina-
         TIMA-sponsored studies on RCF in                     tions,diagnosisandtreaf , aalinjuriesandon-the-job
         which rats and hamsters were exposed                 illnesses, medical cert -sHA health surveillance
         by inhalation to the maximum tolerated                examinations, and retu ~`t : ork ev.~~ .- _~ns .
                                                                                                    .~ .
         dose (MTD) only . In the earlier studies,             BENEFITS : Forty hourw' week, u„i ; ,titive salary and excellent
         the authors selected these two species as             benefit package . A Masters of Public He?!th Program leading to
         appropriate for evaluating the carcino-               board cerfificatir`r l+ , :>c. upational Medick, I ,,_~Iable . Idaho Falls
         genicity of these fibers. In the hamster              areaisunst~ :- • ~ , -adoorrecreationa . :- - . 7 t" Ps,locatedin
         study, 42% of those exposed to the                    thevicirn*, c f rf y, Jackson Holeand ti,                     - p &Teton
         MTD of "RCF I" (kaolin) developed
         mesothelioma, whereas no mesothe-                                                        Employment Scrvicy`5
         liomas were observed in the air control               (GLA-002), EGAG Idahq Inc, R0 . Ro . 1625 . Iciaho Falls, ID
         nor in the positive control animals ex-
                                                               8341 ~ 5-:3127 .
         posed to chrysotile asbestos . Pulmonary
                                                                              ~; ,iortunlty employer. U .S. ciN a
         tumors were not observed in any group
         of hamsters.
             On the other hand, in the MTD rat
         study, the incidence of inesothelioma
         (1 .6%) was not significantly elevated.
         For this RCF 1-exposed group, there                             n EGz G ldaho, Inc.
         was a 6 .5% incidence of both pulmo-
         nary adenomas and carcinomas for a                             G•

                 1174                                                                                                       Letters to the Editor

                 statistically significant findings . This   rates were individually within or near       (n = 4) of the 22 workers with greater
                 comparison of the MTD and multidose         historical control values), if fiberglass    than 20 years since first RCF exposure
                 study results is improper. The multidose    was slightly less carcinogenic than RCF,     in a production job .
                 study was not well designed . A well-       it might not produce a significantly ele-       Bunn et al give the impression that
                 designed study would have repeated the      vated total tumor rate at the MTD .          definitive studies on fiberglass indicate
                 MTD concentration as well as the posi-      Given the dramatic response to RCF           no hazard . This is clearly not the case.
                 tive control .                              observed in the hamster (42% developed       The animal studies have not used the
                    To summarize the above findings on       mesotheliomas), the inclusion of the rat     appropriate methodology and species to
                 rats exposed by inhalation to RCF : the     only in the fiberglass (and mineral wool)    evaluate cancer risk . Epidemiological
                 study of rats exposed to the MTD of         study is inappropriate and suggests se-      evidence indicates an increased lung
                 RCF found that the total lung tumor         lection of a relatively nonresponsive spe-   cancer risk among workers employed in
                 rate (but not adenoma, carcinoma, or        cies for study .                             fiberglass and mineral wool production .
                 mesothelioma rates) was significantly el-      Bunn et al also state that "No sub-       For some of these studies, the role of
                 evated compared with air controls . The     stantive evidence of long-term adverse       potential confounding factors associated
                 multidose rat study of RCF found no         effects has been published in workers        with the elevated lung cancer risk could
                 significant increase in tumor rate at any   exposed to man-made vitreous fibers ."       not be determined . In our opinion, a
                 exposure level .                            However, there have actually been sev-       more cautious view of the carcinogen-
                    Given these findings, it is not unex-    eral studies published that have dem-        icity of these fibers should be expressed,
                 pected that the multidose rat study of      onstrated increased rates of respiratory     lest we repeat the mistakes that occurred
                 fiberglass (with exposure concentrations    tract cancer in SMF manufacturing            with asbestos.
                 of 30, 16, and 3 mg/m') would produce       workers. Shannon et alz observed a sig-
                 no statistically significant findings of    nificantly increased risk of lung cancer                  Loretta D . Schuman, PhD
                 pulmonary tumors or mesotheliomas . If      in 2,557 production workers in a Cana-                 Peter F. Infante, DDS, DrPH
                 fiberglass had the same carcinogenic po-    dian glass wool plant . For plant workers            Occupational Safety and Health
                 tential as RCF, one would not expect to     overall, the standardized mortality ratio                            Administration
                 observe tumor rates at half the MTD         (SMR) for lung cancer was 199 (P <                                  Washington, DC
                 that would be significantly above con-      .05). The authors believed that such an
                 trol levels, because this was true of the   increase was probably too large to be        * These views do not necessarily reflect
                 rat response to RCF . Because the rat       attributable solely to smoking. For those    those of the Occupational Safety and
                 response to RCF was only significant at     workers with more than 30 years since        Health Administration.
                 the MTD (and adenoma and carcinoma          first exposure, the SMR was 270 . Signif-
                                                             icantly increased death rates from res-      References
                                                             piratory tract cancer in fiberglass and
                                                             mineral wool production workers were          t . Bunn III WB, Bender JR, Hesterberg
                                                                                                             TW, Chase GR, Koozen JL Recent
                               RET V nN1®                    shown in large studies in the United
                                                                                                             studies of man-made vitreous fibers . J
                                                             States (16,661 SMF workers) and Eu-
                                                                                                              Occup Med. 1993;35 :101-113.
                                                             rope (24,609 SMF workers) .3-5 For ex-       2. Shannon HS, Jamieson E, Julian JA,
                                                             ample, for fiberglass production workers        Muir DCF, Walsh C. Mortality experi-
                           RETURIV® Plus                     whose first exposure had occurred 20            ence of Ontario glass fibre workers-
                        Occupational Health Manager          (United States) or 30 (Europe) years ago,       extended follow-up . Ann Occup Hyg.
                            PC and LAN Software
                                                             the SMR values were 129.5 (P < .01)              1987 ;31 :657-662 .
                                  Ginic Visits               and 173 (P < .05) for US and European        3. Enterline PE, Marsh GM, Henderson V,
                          All Medical Surveillance           workers, respectively.l7te authors of the       Callahan C. Mortality update of a cohort
                      (Audio, DOT, Drug Saeen, Blood         US study suggested that some other              of US man-made mineral fibre workers.
                           Bome Pathogens, and                                                               Ann Occup Hyg. 1987;31 :625-656.
                                                             contaminant in the workplace
                            all other - User Defined)                                                     4. Marsh GM, Enterline PE, Stone RA,
                                                             may have caused the excess respiratory           Henderson VL. Mortality among a co-
                              Treatment, Referrals
                        Scheduling, Random Sampling          tract cancer .                                   hort of US man-made mineral fiber
                           Managed Workers' Comp                RCF production workers are the sub-           workers: 1985 follow-up. J Occup Med.
                                                      w      ject of an ongoing epidemiological study         1990 ;32 :594-604 .
                             Strong, Flexible Billing        being conducted by Lockey et al .b In-       5 . Simonato L, Fletcher AC, Cherrie J, et
                          Consolidated and Discounts         terim results of this longitudinal mor-          al . The International Agency for Re-
                                                             bidity study showed an increased prev-           search on Cancer historical cohort study
                            Technical Support for                                                             of MMMF production workers in seven
                                                             alence of pleuritic chest pain and de-
                          Electronic Data Exchange                                                            European countries: extension of the fol-
                                Customization                creased pulmonary function, both
                                                                                                              low-up . Ann Occup Hyg. 1987;31 :603-
                                                             associated with duration of exposure .
                                                             Chest radiographs revealed that the          6 . I-ockey J, LeMaste :s G, Rice C, et al . An
                            H M T                            prevalence of pleural plaques overall in         industry-wide pulmonary morbidity
                                                             the 602 RCF production workers was              study of workers manufacturing refrao
                     Health Management Technologies, Ine .
                                                             2.4% (n = 12), whereas the prevalence           tory ceramic fibers and RCF products.
                        1042 Country Club Dr., Suite C
                                                             in the 139 nonproduction workers was            OSHA Docket No. H-020A, Exhibit 1-
                              Moraga, CA 94556
                                1-800-647-7007               0% . Pleural plaques were seen in 18 .2%         52 (TIMA Inc 1990a).

                                                                                                                                  50983 3194

       JOM • Volume 35, Number 12, December 1993                                                                                                                                                     1175

        The Authors Reply                             that male Fischer 344/N rats can de-            sumed to not possess significant carcin-
                                                      velop fibrosis and pulmonary neo-               ogenic potential by that route of expo-
                                                      plasms with a known carcinogenic fiber          sure. This is a fundamental principle in
         To the Editor: In response to the letter     under the conditions of the experiment.         carcinogenesis bioassays .
        from Drs Schuman and Infante, the au-         This was adequately demonstrated with              Drs Schuman and Infante stated,
        thors would like to comment on several        chrysotile asbestos in the original RCF         "Given the dramatic response to RCF
        factual and scientific issues. While we       MTD study and subsequently with cro-            observed in the hamster (42% developed
        recognize that the scientific process can     cidolite asbestos, using almost identical       mesotheliomas), the inclusion of the rat
        and does allow for honest disagreement        protocols.                                      only in the fiberglass (and mineral wool)
        in procedure, presentation, and inter-           Drs Schuman and Infante also                 study is inappropriate and suggests se-
        pretation, we take exception to the opin-     seemed to imply that the proper way to          lection of a relatively non-responsive
        ions expressed by Drs Schuman and             evaluate lung tumor data is to analyze          species for study ." For the following rea-
        Infante and sincerely believe that the        benign and malignant neoplasms sepa-            sons (detailed below) we disagree with
        research under discussion withstands          rately. Not only do most researchers feel       this opinion as well : scientific judgment
        the highest levels of scientific scrutiny .   that pulmonary adenomas and carcino-            then and now supports the protocol ; the
        The scientific process and the resulting      mas should be combined for statistical          ultimate outcome ofthe RCF inhalation
        chronic studies discussed not only in-        purpose,' it is well known that the Na-         studies show the rat as the better model ;
        volved seeking advice from some of the        tional Toxicology Program (NTP) rou-            and interim data from the RCF study
        leading scientists in the field, but also     tinely combines benign and malignant            available at the time the fiberglass study
        advanced the understanding of fiber           neoplasms for analysis. The reason for          was initiated gave no indication of final
        toxicology .                                  this approach is that the progression           study results .
            After repeating a number of facts         from pulmonary adenoma to carcinoma                First and foremost, the protocol de-
        about which there is no disagreement,         is a continuum and differential diagnos-        sign, including the animal model, was
        Drs Schuman and Infante expressed             tic criteria used in making these diag-         developed using scientific judgment that
        their opinion on several issues that we       noses are somewhat arbitrary and have           has subsequently been reaffirmed . In
        would like to address specifically . Those    little bearing on the eventual biological       conducting a chronic bioassay the ani-
        issues are: 1) the design of the refractory   potential of these lesions.                     mal model selected should be sensitive
        ceramic fiber (RCF) multidose study, 2)          Another statement of Drs Schuman
       the analysis of tumor data, 3) their spec-     and Infants deserves comment . They
        ulation that a concentration of fiber         state " . . . if fiberglass was slightly less
       glass higher than the maximum toler-           carcinogenic than RCF, it might not
       ated dose (MTD) might be carcinogenic          produce a significantly elevated total tu-       PHYSICAL MEDICINE RESEARCH FOUNDATION
       in the rat, 4) their opinion that the rat      mor rate at MTD." First, one fiberglass
                                                                                                        7TH INTERNATIONAL SYMPOSIUM
       model was an inappropriate choice and          composition (MMVF 11) was tested at                  Vancower, Onada • June 10 -12,199f
       is a relatively nonresponsive species, and     an exposure level higher than the RCF              Repetitive Strain Injuries, Fihromyalgia &
       5) their comments regarding epidemiol-         in the RCF MTD study (246 . WHO f/cc             Chronic Fatigue Syndrome; Current Concepts
       ogy studies.                                                                                     in Diagnosis, Management & Cost Containment
                                                      vs 187 WHO f/cc for RCF 1) and the
                                                                                                                                   Symposium Chairs
           Drs Schuman and Infante asserted           resulting lung fiber burdens were ao-            •Dc Mdrsw Chalmers, Associate Professor, Head,
       that the RCF multidose study was not           tually twice as high as in the RCF ani-          Division of R6eumatology, University of British
                                                                                                       Columbia, Canada;
       well designed because the MTD dose of          mals at the end of exposure .' Despite           •Dn Frederlck Wolfe, Cfinkal ProfessorofMedicinq
       RCF and the positive control were not          this high lung burden of glass fibers, no        Univrsiry of Kansas, USA;
                                                                                                       •Dr.Irv5alil, ProlessorandHead, DivisionoFlnfectious Diseases, University ofToronto, Canada
       repeated. These exposure groups were           fibrosis or significant increase in lung                                             ;
       included in the RCF MTD study and              tumors was observed . If fiberglass was          •nr . Geoffrey Littlejohn, Associate Professor of
                                                                                                       Medicine, Monash University, Australia
       were not repeated in the multidose study       only "slightly less carcinogenic than
       because the two studies overlapped in          RCF" one would have expected to have                CALL FOR PAPERS & POSTERS
       time by one and a half years and were          at least observed some lung fibrosis at          The Physical Medicine Research
       conducted in the same laboratory, with         the MTD concentration, but in fact no            Foundation in association with the
       the same exposure system, using the            fibrosis was seen in fiberglass exposed          Divisions of Rheumatology and Infectious
       same source, species, and strain of rat .      animals. Fibrosis has been observed in           Diseases, University of British Columbia
                                                                                                       is inviting clinicians and researchers to
       Further, the lung burden studies docu-         every fiber inhalation study that has re-        submit abstracts for review . Issues include :
       ment the excellent and consistent con-         sulted in lung tumors.3 In fact, lung            causality, functional capacity
       trol of dose by RCC. We see no scientific      fibrosis was observed at noncarcino-             determination, prognosis, treatment and
       justification whatever (and none was of-       genic levels of RCF as low as 75 f/oc,           compensation adjudication.The deadline
       fered by Drs Schuman and Infante) for          less than one-third the fiber concentra-         for submission is February 1, 1994 .
       repeating the high dose because the                                                                For abstract guidelines, exhibit and
                                                      tion of the MTD dose of fiberglass. Thus
                                                                                                            registration information contact :
       overwhelming fibrosis and tumor re-            not only is there no scientific basis for
                                                                                                                     Marc 1. White
       sponse rates clearly indicate what should      Schuman and Infante to speculate that
       happen .                                       fiberglass is only slightly less carcino-               Physical Medicine Research Foundation
           Similarly, we find little reason to re-    genic than RCF in rats, the data clearly                     N510- 207 LVest Hastings St .,
                                                                                                                 Vancouver, BC V661H7 Canada
       peat the positive control . The reason one     refute such a premise.
                                                                                                               Tel : (604) 684-1148 or (604) 684-5345
       uses a positive control is to verify the          In addition, if a material does not                             Fax: (604) 684-6247
       model, ie, in this case to demonstrate         cause tumors at the MTD, it is pre-

                   1176                                                                                                        Letters to the Editor

                   to the endpoints of interest . Two recent    later) . Drs Schuman and Infante clearly    RCC inhalation studies were orders of
                   international conferences"•' have both       misunderstood this fact. Even if the ad-    magnitude higher than typical occupa-
                  concluded that the rat is the preferred      ditional information on the RCC ham-         tional exposures . These data further add
                   model for evaluating the potential fibro-   ster study had been available at that        to the weight of the evidence that respi-
                  genic and pulmonary carcinogenic              time, based on the previous discussion,     rable fiberglass represents no significant
                  properties of airborne fibers . Rats pro-    the rat clearly would have been the          hazard for disease in humans .
                  vide a better indication of the spectrum      model for choice .                             A substantial effort was made by in-
                  of potential diseases which could be             Regarding their comment on human         dustry to brief scientists from the federal
                  caused by inhaled particles . In addition,   studies, we are sure Drs Schuman and         regulatory community during all phases
                  more testing has been conducted in rats       Infante recognized that the transitional    of the RCC study-EPA, CPSC,
                  than hamsters, which allows more com-        statement referring to the epidemiology      MOSH, MEHS, and OSHA (including
                  plete comparisons between studies, pro-      was simply additional information for        Drs Schuman and Infante). The authors
                  viding analysis of the strength and          the readers as to why the animal studies     continue to welcome informed dia-
                  weight of the scientific evidence. Ham-      were undertaken in the first place . As      logue on the results of these and all
                  sters have not shown the same breadth        stated in the article, the purpose was to    previous studies of glass fibers . We are
                  of response and appear to be refractory      provide an update on chronic animal          confident, however, that the study de-
                  to the induction of lung neoplasms with      inhalation studies of MMVF, not epi-         sign and quality withstand sound scien-
                  known carcinogenic fibers, eg, various       demiologic studies. For a full and bal-      tific scrutiny .
                  forms of asbestos.b                          anced discussion, we naturally prefer
                     Furthermore, the RCF rat studies          that readers rely on research and reviews                 W. B . Bunn, MD, JD, MPH
                  showed not only significant numbers of       that specifically address the epidemiol-                      J . R . Bender, PhD, MD
                  lung cancer, but also (biologically) sig-    ogy and suggest that readers refer to                          T . W . Hesterberg, PhD
                  nificant numbers of mesothelioma were        assessments by the principal research                                G. R. Chase, PhD
                  observed (no spontaneous pleural meso-       investigators of the major epidemiologic                      J. L Konzen, MD, MPH
                  thelioma tumors were reported in either      studies (eg, see Marsha) . We emphati-                           Princeton, New Jersey
                  rats or hamsters in the many studies         cally disagree with their selective cita-
                  cited in our article) . Epidemiologicstud-   tions that do not present a balanced         References
                  ies of fiberglass workers do not indicate    overview of the weight of the evidence
                                                                                                              1 . McConnell EE, Solleveld HA, Boomian
                  a risk of mesothelioma, even though the      and can be misleading . Epidemiological            GA . Guidelines for combining neo-
                  studies date back over 50 years-impor-       studies do not support a causative rela-           plasms as evidence of carcinogenicity in
                  tant because of the long latency period      tionship between glasswool fiber expo-             long term toxicity and carcinogenesi ;
                  normally associated with the develop-        sure and cancer. Both IARC9 and the                studies . JNCI. 1986;76:283-289.
                  ment of inesothelioma . Because the rat      EPAs Office of Toxic Substances10 have        2. Hesterberg TW, Miller WC, McConnell
                  is clearly the preferred animal model for     concluded, based on extensive epide-              EE, et aL Chronic inhalation toxicity ol
                  evaluating lung cancer potential of air-      miological studies, that the evidence is          size-separated glass fibers in fischer 344
                                                                                                                  rats . Fundam Appl Toxicol. 1993 ;20 :
                  bome fibers and also showed biolog-           inadequate for carcinogenicity in hu-
                                                                                                                  464-476 .
                  ically significant mesothelioma, the rat      mans. This is further supported by an
                                                                                                             3 . Hesterberg TW, Vu V, Chase GR,
                  was the appropriate selection for the        article in this journal by Marsh et al."           McConnell EE, Bunn WB, Anderson R.
                  current study. Notwithstanding, a better         Fibrous glass has been tested by in-           Use of animal models to study man-
                  understanding of the differences in          halation in guinea pigs, hamsters, and             made fiber carcinogenesis. In Brinkly B,
                  mechanisms between rats and hamsters         in eight separate inhalation studies in            Lechner L, Harris C, eds. Cellular and
                  in their responses to inhaled fibers is of   rats . None of these studies identified a          Molecular Aspects of Fiber Carcinogen-
                  obvious interest.                            significant increase in either fibrosis or         esis. Cold Spring Harbor, NY: Cold
                     It is also informative to look at the     neoplasms following fiberglass inhala-             Spring Harbor Laboratory, 1991 ;183-
                  protocol from the perspective of what        tion in spite of lung burdens in excess            205 .
                                                                                                             4 . WHO . Validity of methods for assess-
                  information was, in fact, available in       of several hundred thousand fibers per
                                                                                                                  ment of carcinogenicity of fibres. Copen-
                  1989 when the fiberglass inhalation          milligram of dry lung tissue. It is note-
                                                                                                                  hagen, Denmark: WHO Regional Office,
                  study was initiated. A previously re-        worthy that lung burdens in the exposed            1992 .
                  ported fiberglass inhalatioa study in        animals in the RCC fiber glass inhala-        5 . McClellan RO, Miller FJ, Hesterberg
                  hamsters' achieved high lung burdens         tion study are orders of magnitude                 TW, et al . Approaches to evaluating the
                  and reported no fibrosis, lung tumors,       higher than those reported recently for            toxicity and carcinogenicity of man-
                  or mesotheliomas. Furthermore, at the        former glass fiber production workers .12          made fibers. Regul Toxicol Pharmacol.
                  time of the initiation of the fiberglass     Lung samples of only 26% of workers                1992 ;16:321-364 .
                  inhalation study, only a single meso-        contained any man-made vitreous fiber,        6 . Hesterberg TW, Mast R, McConnell EE,
                                                                                                                  et al. Chronic inhalation toxicity of re-
                  thelioma (not the 42% eventually ob-         almost all siliceous in nature and in low
                                                                                                                  fractory ceramic fibers in Syrian ham-
                  served and mentioned by Drs Schuman          concentration . Those that did contain
                                                                                                                 sters. In : Brown RC, Hoslcins JA, John-
                  and Infante) had been observed in the        fibers averaged only 200 fibers per mil-
                                                                                                                 son NF, eds. Mechanisms in Fibre Car-
                  RCF MTD hamster inhalation study             ligram of dry lung tissue, compared with          cinogenesis. Plenum Press, 1991 ;531-
                  and the RCF rat inhalation study             more than 600,000 in the highest fiber-            538 .
                  showed fibrosis (with the longer life span   glass exposure group in the RCC study .       7. Smith DM, Ortiz LW, Archuleta RF,
                  for the mt, tumors would appear months       Furthermore, the exposure levels in the           Johnson NF. Long-term health effects in

                                                                                                                    50983 3196

      " JOM • Volume 35, Number 12, December 1993                                                                                          1177

             hamsters and rats exposed chronically to    be happy to answer any questions any         Public Health (CEPH) was obtained in
             man-made vitreous fibres . Ann Occup        reader may have .                             1991 .
             Hyg. 1987;31 :731-754.                                                                      Although a description of the pro-
         8 . Marsh GM . The University of Pittsbu`gh                                                  gram has appeared in the context of
             epidemiology studies of man-made min-             William W . Greaves, MD, MSPH          a proposed program in insurance
             erzl fiber workers . The Toxicology                    Acting Chair, Department of       medicine' and through international
             Forum proceeding of the Annual Winter
                                                                                                      meeting presentations abroad,°'b we be-
             Meetingsin Washington, DC . 1992 :311-
             335 .                                                                                    lieved that a brief summary of the man-
         9 . IARC (International Agency for Re-                                                       ner in which the program is conducted
                                                         The Off-Campus Approach to Training
             search on Cancer). IARC Monograph on                                                     would be of interest to the JOM read-
                                                         Occupational Health Professionals            ership here in the United States.
             the Evaluation of Carcinogenic Risks to
             Human Man-Made Mineral Fibers and                                                           The necessary ingredients for such a
             Radon, Lyon, France, Vol. 43 ; 1988 .        To the Editor: Efforts to meet the need
                                                                                                      training program to succeed include spe-
        10. US Environmental Protection Agency.           to train physicians in occupational med-
                                                                                                      cially designed course study guides with
             Health Hazard Assessment of Nonasbes-        icine throughout the world have resulted
                                                                                                      clear-cut learning objectives, access to
             tos Fibers. Health and Environmental         in several approaches as alternatives to
                                                                                                      and involvement in an actual work-site,
             Review Division, Office of Toxic Sub-        full-time attendance during a standard
             stances. F'inal Draft . 1988.                                                            a faculty of limited size who are respon-
                                                          academic year.                              sive to the students' needs, and a highly
        11 . Marsh GM, Enterline PE, Stone RA,               Weekend programs and summer ses-
             Henderson VL . Mortality among a co-                                                     motivated mature group of students ca-
                                                          sions have been in place at various
             hort of US man-made mineral fiber                                                        pable of assuming responsibility for the
                                                          schools for some time. One of these, the
             workers: 1985 follow-up . ! Occup Med.                                                   attainment of the study objectives .
             1990 ;32394-604.                             program at the University of Michigan,         Entering students attend a one-day
        12 . McDonald SC, Case BW, Enterline PE,          was recently described in this Journal in   introductory session at the Medical Col-
             et al . Lung dust analysis in the assess-    a Letter to the Editor.'
                                                                                                      lege of Wisconsin . This orientation ses-
             ment of past exposure of man-made              The off-campus program of the Med-        sion introduces each component of the
             mineral fibre workers. Ann Occup Hyg.        ical College of Wisconsin, which to date    program and the practical aspects of the
             1990 ;34 :427-441 .                          has enrolled 637 physicians, is unique
                                                                                                      Activity Assignments and the computer-
                                                          in that it does not require any on-cam-
                                                                                                      based testing.
                                                          pus activity other than one day of ori-
                                                                                                         The curriculum is designed to encom-
       The computer administered quizzes are             entation at the beginning of the pro-
                                                                                                      pass the major disciplines in the spe-
       teaching devices to enable the students           gram. The program currently is limited       cialty of occupational medicine. Stu-
       to assess their progress and guide them-          to physicians engaged in activities re-      dents must complete 30 trimester credit
       selves in finding the basis for the appro-        lated to occupational medicine, al-          hours that include the five required core
       priate answer when the one selected is            though 10 nonphysician occupational
                                                                                                      courses for CEPH accreditation and the
       incorrect . All courses are concluded             health professionals have been admitted
                                                                                                      two-semester project course . Students
       with a proctored final exam, which may            as special students and are eturently pur-   choose from the elective courses to fulfill
       be administered at a college or univer-           suing their course work
                                                                                                      the remaining credit requirements . Each
       sity accessible to the student .                     Enrollees have come from 48 of the
                                                                                                      3-credit course is normally completed
          The final project course incorporates          50 states (all but Mississippi and Mon-
                                                                                                      every trimester, ie, every four months .
       the knowledge and skills learned in the           tana) and from 6 foreign countries : Can-
       basic courses and requires the student            ada, Panama, Puerto Rico, Saudi Ara-
                                                                                                                 Required Courses
       to apply the principles and practices of          bia, Trinidad, and the Virgin Islands .
       occupational medicine to a real problem              Agreements have been developed
       in his or her setting .                           with two foreign countries, Thailand
                                                                                                              Environmental Health
          Enrollment occurs three times a year           and the Republic of Georgia, making
                                                                                                          Health Services Administration
       and all courses are offered at all times .        available all educational materials in re-
                                                                                                       Behavioral Science and Occupational
       It is expected that if a student takes one        turn for reimbursement for a portion of
       course per trimester, he or she can com-          our developmental costs over time as
                                                                                                        Project in Occupational Medicine
       plete the requirements for the MPH de-            these programs enroll students. Thus
       gree in 3 93 years . Two students of the 89       far, Thailand has enrolled 152 students .
       graduates of the program have com-                   Development of the program began
                                                                                                        Practice of Occupational Medicine
       pleted the program in 14 months . Also,           in 1983 with a modest grant from the
                                                                                                               Clinical Prevention
       students enrolled in residency programs           National Fund for Medical Education .
       in which the academic and practicum               Individual courses were accepted by the
                                                                                                                Industrial Hygiene                  i
       years are completed concomitantly nor-            American Board of Preventive Medicine
                                                                                                        Occupational Health Surveillance
       mally take two calendar years to com-             beginning in 1985 under its Alternative
                                                                                                          Introduction to Public Health
       plete the degree requirements. Students           Pathway program for pre-1984 gradu-
                                                                                                            Occupational Health Law
       may enroll for specific courses regardless        ates,z and authorization for Medical
       of whether they intend to complete the            College of Wisconsin's Department of            For each course, there is a specially
       requirements for the MPH degree.                  Preventive Medicine to award an MPH          developed "Course Study Guide,"which
          The authors or other faculty members           degree was granted in 1988 . Accredita-      includes the following:
       or staff involved in the program would            tion by the Council on Education for                 Course goals and objectives


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