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FILE NAME: Talc (TALC) DATE: 1980 DOC#: TALC106 DOCUMENT DESCRIPTION: NIOSH Report - Occupational Exposu to Talc Containing Asbestos -^%' -a - OCCUPATIONAL EXPOSURE to TALC CONTAINING ASBESTOS ' ' - ; . ' h- u. S. DEPARTMENT OF HEALTH, Public Health Service Center for Disease Control National Institute for Occupational ' EDUCATION, AND Safety and Health WELFARE CONTENTS ABSTRACT .................................................. ACKNOWLEDGMENTS .............................................. ' * DEFINITIONS .................................................. INTRODUCTION .............................................. * DESCRIPTION OF FACILITIES STUDIED.................... *. INDUSTRIAL HYGIENE STUDY .................................... Methods ........................................................ Results ........................................................ Comparison of Present and Past Exposures . . Comparison o f Exposure Character!'sites with Other Talc Mines and M ills in the Gouverneur, New York Area .............................................. REVIEW OF HEALTH EFFECTS FROM EXPOSURE TO TALCS CONTAINING ASBESTIFORM AND ASSOCIATION MINERALS . Respiratory M orbidity Studies .................... M o rta lity Studies ..................................... CROSS SECTIONAL MORBIDITY STUDY ........................... D escription o f Work Force ........................... M aterials and Methods ................................. R e s u l t s ..................................................] * D is c u s s io n .............................................. ] [ RETROSPECTIVE COHORT STUDY OF MORTALITY ! .* .* Methods ........................................................ Results . *........................................... .*.*.* D is c u s s io n ........................................... *. ! *. CONCLUSIONS AND RECOMMENDATIONS............. T A B L E S .................................... FIGURES .......................... . . . . . R E F E R E N C E S ................................. ............. * * * * A P P E N D IX ........................................... Summary S t a tis tic s fo r NIOSH 1975 Industrial* Hygiene Study ii i xi xi i i 10 11 11 16 19 19 19 20 24 29 29 29 31 33 35 82 89 97 Ol i-- I C O L O LT) v TABLES 1. Results of X-ray d if fr a c t io n and petro graphic microscopic analysis of bulk t a lc samples co lle c te d duringstudy ............................ 35 2. Results o f trace metal analyses o f bulk t a lc samples co lle c te d duringstudy ............................ 36 3. Results o f major components analyses o f product t a lc sa m p le s.........................................................37 4. Summary o f TWA exposures by job, mining o p e r a tio n s ......................................................................... 38 5. Summary o f TWA exposures by job t i t l e ....................... 39 6. Summary of TWA amphibole fib e r exposures (a ll fib e r lengths) determined by electron microscopy . . . 40 7. Summary of airborne fib e r types determined by a n a ly tic a l electron microscopy .................................... 41 8. Summary of airborne fib e r diameters fo r p o sitiv e amphiboles ..................................................... 42 9. Summary of airborne fib e r lengths fo r p o sitiv e amphiboles ..................................................... 42 10. Aspect ra tio s fo r p o sitiv e amphiboles determined by electron microscopy .............................. 43 11. Summary of h is t o r ic impinger dust measurements in mine and m ill o p e r a t i o n s ............................................44 12. Sunmary of h is to r ic fib e r exposure measurements in mine and m ill o p e r a t i o n s ........................................... 45 13. Comparison of airborne fib e r character is t ic s in study o f mine and m ill operations with New York t a lc operations acknowledged as containing asbestiform minerals .............................. 46 14. Summary of m orbidity studies of workers exposed to trem olite and/or an th op h yllite fib e rs 47 Si *j: 15. Age-smoking composition o f m orbidity study population who had no previous occupational exposure to t a l c .............................................................. 55 15A. Age-smoking composition of to ta l m orbidity study population regardless of previous employment......................................................................... 56 16. Age-exposure composition o f m orbidity study population who had no previous occupational exposure to t a l c .............................................................. 57 16A. Age-exposure composition of to ta l m orbidity study population regardless o f previous employment . . 57 17. Prevalence ( a ) of symptoms and radiographic fin d in g s by smoking habits among m orbidity study population who had no previous occupational exposure to t a l c ........................................................... 58 17A. 18. Prevalence ( a ) of symptoms and radiographic fin d in g s by smoking habits among the to ta l m orbidity study population regardless of previous employment . . 59 Prevalence ( a ) o f symptoms and radiographic fin d in g s by age among m orbidity study popula tio n who had no previous occupational exposure to t a l c .........................................................................60 18A. Prevalence ( a ) of symptoms and radiographic fin d in g s by age among the to ta l m orbidity study population regardless of previous employment......................................................................... 61 19. Prevalence ( a ) o f symptoms and radiographic fin d in g s among t a lc workers included in m orbidity study with no previous occupational exposure to t a lc compared to coal and potash workers adjusted fo r age, height and smoking h a b i t s ............................................................................... 62 19A. Prevalence ( a ) o f symptoms and radiographic fin d in g s among a ll t a lc workers included in m orbidity study compared to coal and potash workers adjusted fo r age, height and smoking h a b i t s ................................................................................63 vn 20. Dose-response re la tio n s among t a lc workers observed pulmonary function as compared to pulmonary function o f coal and potash miners, adjusted fo r age, height, smoking habits and years worked (Standard error in parentheses.) . . . . 64 21. Comparison of t a lc workers included in m orbidity study and having no previous t a lc exposure, with Si and without pleural thickening (PT)* by age, exposure and smoking h abits. (Standard error in parentheses.) N=93................................................. 67 21A. Comparison o f a ll t a lc workers in m orbidity study with and without pleural thickening (PT)* by age, exposure and smoking habits (Standard error in parentheses.) N=121 ..................................................... 68 22. Average number o f years worked fo r each in d ivid u a l in m orbidity study having no previous t a lc exposure with and without pleural thickening and the number of these in d iv id u a ls working in selected jobs over the to ta l work h isto ry of those with greater than 15 years work when 0, 5 and 10 of the most recent years are omitted .......................... . 69 23. Symptom prevalence, radiographic fin d in g s , and pulmonary function o f t a lc workers in m orbidity study by pleural thickening (PT) and years employment .................................................................. . 70 24. Symptom prevalence (a) of t a lc workers in m orbidity study compared to asbestos-^ and synthetic t e x t ile workers^ by age and smoking habits ............. 71 25. Prevalence of radiographic fin d in g s of t a lc workers in m orbidity study compared to asbestos workers^ over 35 years o f age and a fte r age adjustment ................................................. . 72 26. Summary o f the prevalence of pleural th ic k ening (PT) in workers exposed to asbestos ............. . 73 27. V ita l status o f 398 t a lc workers included in m o rta lity study who began employment between 1947-1960 ..................................................... . 75 VI 11 28. Study cohort o f t a lc workers included in m orta lity study according to length of employment......................................................................... 75 29. Study cohort of t a lc workers included in m ortality study according to date of i n i t i a l employment ........................................................ 76 30. Observed and expected deaths according to major cause among t a lc miners and m ille rs included in m o rta lity study ........................................ 77 30A. Observed and expected deaths according to s p e c ific cause among t a lc miners and m ille r s included in m o rta lity s t u d y ............................................................ 78 31. Bronchogenic cancer among t a lc miners and m ille rs included in m ortality study according to in te rv a l since onset o f employment (latency) . . . 79 32. Case review of deaths among t a lc miners and m ille rs included in m ortality study according to cause of death and se le c t demographic facto rs . . . 80 FIGURES 1. Electron d iffr a c t io n patterns and x-ray spectra o f trem olite fib e rs in bulk samples ............. 82 2. Electron d iffr a c t io n patterns and x-ray spectra o f a n th op h yllite fib e rs in bulk samples .................... 83 3. Electron photomicrograph of airborne par t ic u la t e s in mine and m i l l ............................................... 84 4. Electron photomicrograph of airborne par tic u la t e s in mine and m i l l ............................................... 85 5. Electron photomicrograph of airborne par t ic u la t e s in mine and m i l l ............................................... 86 6 . Mean yearly impinger dust concentrations fo r mine o p e r a t i o n s .........................................................87 7. Mean yealy impinger dust concentrations fo r m ill o p e r a t i o n s .........................................................88 IX ACKNOWLEDGMENTS The assistance of the fo llo w in g is acknowledged: Mike Grannan and E ric Kus o f NIOSH and Jim S alois o f MESA in c o lle c tio n o f the in d u s tria l hygiene samples; Mike Grannan, Robert P h illip s and Kenneth M. W allingford in the o p tic a l asbestos fib e r ' analyses; Terry Boyle and Dennis Roberts in reduction of the f i e l d and laboratory data; Dr. D.R. Bowes o f the U n iversity of Glasgow in analysis of major elements of t a lc bulk samples; W.C. McCrone Associates and the Mt. Sinai School o f Medicine o f the C ity U niversity o f New York in an alysis of t a lc bulk sample We wish to thank the s t a ff o f the Biometry Section fo r th e ir help in assembling the necessary data fo r the m o rta lity study and in preparing the manuscript. The guidance o f Richard Lemen was e s p e c ia lly h e lp fu l. The time and e ffo r t o f the f ie ld teams that p a rticip a te d in the c o lle c tio n of data fo r the m orbidity study was greatly appreciated. DEFINITIONS COUGH YES to the question, "Do you cough lik e t h is on most days fo r as much as three months each year?" DYSPNEA YES to the question, "Do you short of breath walking with people your own age on level ground?" get other FEF25, FEF50s FEF75 Forced Expiratory Flow (lite rs/seco n d ) at 25 percent, 50 percent and 75 percent of expired FVC. FEV -j Forced Expiratory Volume in one second ( lit e r s ) . FEV percent FEVt/FVC x 100. FVC Forced V ita l Capacity ( lit e r s ) . HEMOPTYSIS YES to the question, "Have you ever coughed up blood?" ; PHLEGM YES to the question, "Do you bring up phlegm lik e th is on most days fo r as much as three months each year?" ! SMR Observed deaths/Expected deaths x 100. TWA Eight-hour time weighted average. x in INTRODUCTION The term "ta lc" in the m ineralogical sense denotes a s p e c ific rockforming mineral of the sheet s ilic a t e category; however, when "ta lc" is referenced in the in d u s tria l or commercial s e ttin g , i t may represent a varied mixture of minerals with physical properties s im ila r to the mineral t a lc (1). Minerals commonly found associated with ta lc include c a lc it e , quartz, diopside, magnesite, serpentines (ch ry so tile , a n tig o rite , and liz a r d it e ) , and fib ro u s and nonfibrous amphiboles (trem olite, anthophyl1it e , a c tin o lite ) (1, 2). The United States produces about 30 percent of the w orld's ta lc with New York, C a lifo rn ia , Vermont, Texas, and Montana accounting fo r three-fourths of the U.S. production. The work fo rce fo r both ta lc mining and m illin g has been estimated to be about 1,200 in over s ix ty - fiv e f a c ilit ie s (3). Largely due to the great v a rie ty of minerals commonly associated with t a lc , few studies have been undertaken which adequately characterize the various minerals to which ta lc workers are exposed and simultaneously delineate the la ten t disease m anifestations associated with those work environments. Recognizing the need fo r addition al research with regard to health hazards from in d u s tria l ta lc exposure, the National In s titu te fo r Occupational Safety and Health ( NIOSH) undertook an industrywide program to study t a lc mining and m illin g in two geographic areas, New York and Vermont. This program includes d etaile d in d u s tria l hygiene studies to characterize the various agents to which workers have been exposed, cross-sectional medical surveys to evaluate re sp ira to ry impairment, and retrospective cohort studies to evaluate latent disease patterns among workers who have been exposed to ta lc in the work environment. The present report r e s t r ic t s i t s e l f to that part of the industrywide study concerning an in v estig a tio n of ta lc s containing fib ro u s amphibole minerals as mined and m illed in the Gouverneur Talc D is t r ic t in upper New York. This t a lc mining d is t r i c t located in St. Lawrence County represents a complex association of amphiboles (anthophyl1it e , trem olite, e tc .) , t a lc , quartz, and serpentines (2, 4). Previous studies by K le in fe ld et a l. (5, 6 ) of asbestiform t a lc miners and m ille rs in th is d is t r i c t have demonstrated s ig n ific a n t ly increased proportional m o rta lity due to both malignant and nonmalignant re sp ira to ry diseases. M orbidity studies also have indicated increased symptoms and X-ray and lung function changes consistent with pneumoconiosis (7, 8 , 9, 10, 11, 12). More 1 recently a ta lc mining company in th is d is t r ic t maintained that these studies were not applicable to a ll ta lc s in the Gouverneur Talc D is t r ic t . The company stated that ta lc s extracted from it s o rig in a l mine in the Gouverneur Talc D is t r ic t do not contain asbestiform minerals and that the ta lc s have been so c e r t ifie d (13). One study, however, at the same operations concluded that asbestiform minerals were contained in the ta lcs (11). To address th is co n tra d ictio n , the present study r e s t r ic t s i t s e l f to that one mine and m ill reported by the company to be producing nonasbestiform ta lc . DESCRIPTION OF FACILITIES STUDIED The company under study began t a lc mining and m illin g operations in the Gouverneur Talc D is t r ic t of upper New York in 1947. Talcs extracted from th is mine are used fo r a variety of applications including ceramics, pottery, artware, e le c tric a l in s u la to rs , ceramic t i l e glaze and flu x , paint f i l l e r s , in p u ttie s, and in spackling compounds. MINING In the study mine, underground hard rock mining methods are employed using jackleg d r i l l s to make holes fo r b la stin g the ore in open stopes. The mine consists of one main shaft 1,250 feet in depth with three main working le v e ls . In 1975, ore was being mined from approximately 6 o f the 26 active stopes. Mining fo llo w s a ty p ica l cycle including: (1 ) b la stin g , which is done with g e la tin dynamite and ammonium n itra te ; (2 ) d is sip a tio n of dusts and gases; (3) removal of ore with some secondary bla sting ; and (4) d r illin g of b la sting holes fo r the next s h ift . Ore (muck) from the stoping areas is loaded into 2-ton r a il cars using e ith e r g ravity drawpoint or scraper (slusher) loading. Ore from these cars is discnarged into a central jaw crusher located at the 700-ft. level although some crushing is also done on the 1,110-ft. le v e l. The crushed ore is loaded into a skip and carried to the mine headframe where a gyratory crusher reduces the ore to approximately 3/4-in. screen siz e . The ore is then transported by conveyor b e lt to one of the four wet ore storage bins in the m ill. Approximately 40,000 cubic fe e t per minute (cfm) o f mining v e n tila tio n is provided. The ore may be inh erently moist, and wet d r illin g is employed. Water sprays are also used fo r dust suppression at the 700-ft. level crusher. According to company personnel, wet d r illin g has been practiced since the beginning of these operations. MILLING M ill operations include cone crushing f i r s t , followed by moisture removal in rotary dryers. The dry ore is further reduced in p a r tic le size using a gyratory disc crusher followed by vibratory screening and transportation to one of six dry ore s ilo s . F in e ly ground products are made from these ores, using e ith e r Hardinge pebble m ills in closed c ir c u it with Raymond separators or impact crushers in closed c ir c u it with flu id energy m ills . The f in e ly ground products are stored in one of several concrete s ilo s and are withdrawn by a ir s lid e s and pumped to the packaging and shipping areas. Talcs are eith e r 3 sold in bulk or packaged in 50-lb. valve-type K raft paper bags. Bag f i l l i n g is done using pneumatic packing machines. In the m ill, most m aterial tran sfer points are provided with loca l exhaust v e n tila tio n , and bucket elevators and conveyors are maintained under negative pressure. At the bagging machines, loca l exhaust v e n tila tio n is provided at the f i l l i n g spout and downdraft v e n tila tio n at the bag hopper. For bulk car loading, the te le sco p ic loading spout is provided with a local exhaust v e n tila tio n c o lla r . 4 INDUSTRIAL HYGIENE STUDY METHODS In order to evaluate occupational exposure c h a ra c te ris tic s and le v e ls among workers in th is mine and m ill and to compare th^m with those pf previous studies o f New York ta lc operations, a d e ta ile d environmental study was undertaken. This study included determinations o f time-weighted average (TWA) exposures to resp ira b le dust, free s i l i c a , and asbestiform minerals in addition to d e ta ile d 'm in e ra lo g ica l assays o f ta lc s produced at the mine and m ill under study. Talc product samples were co lle c te d during the study (samples A -F),a n d ad dition al product samples from the mine and m ill being studied were submitted by the company (samples 1-7). Analyses o f co lle cte d bulk t a lc samples were performed by both NIOSH and independent research la b o ra to rie s. These analyses included X-ray d iffr a c t io n , o p tica l petrographic microscopy, and electron microscopy. For X-ray d iffr a c t io n studies, step scanning o f diagnostic re fle c tio n s fo r the asbestiform minerals and quartz was used (1). Electron d iffr a c t io n and microchemical analyses o f in d ivid u al fib e rs were performed by electron microscopy (14, 15). Bulk t a lc samples were also analyzed fo r major oxide composition and trace metal contamination. These analyses were performed using spectrophotometry, atomic absorption, and flame photometry (1 ). Personal a ir samples were co lle c te d from the breathing zone of miners and m ille rs to determine TWA exposures to re sp irab le dust, free s i l i c a , and mineral fib e r s . Personal samples fo r re sp ira b le dust and free s i l i c a were co lle cte d at a flow rate of 1.7 l i t e r s per minute (1pm) using 37-mm diameter polyvinyl ch lo rid e f i l t e r s (preweighed) preceded by 10-mm nylon cyclone separators. Samples fo r fib e r an alysis were co lle c te d on open-faced 37-mm diameter M illip o r e Type AA f i l t e r s (0.8-vim pore size ) at a flow rate of 1.7 1pm. Respirable dust samples were co lle c te d fo r the f u l l work s h if t periods while fib e r samples were changed p e rio d ic a lly during the work s h if t as needed to prevent overloading o f f ilt e r s . Free s i l i c a concentrations were determined using X-ray d if fr a c t io n as sp e cifie d in the NIOSH C r it e r ia Document (15). A ll fib e r samples were analyzed using the NIOSH phase contrast counting technique (17). In a d d ition , a representative number of the in d iv id u a l fib e r samples was randomly chosen and the samples were analyzed by electron microscopy using selected area electron d iffr a c t io n and energy d ispersive X-ray an alysis fo r 5 fib e r id e n t ific a t io n . Electron microscopy was also used to determine airborne fib e r concentrations and size (diameter and length) d is trib u tio n s (14). Samples fo r electron m icroscopic an alysis were prepared using methods previous described (15). In order to compare re s u lts o f the present in d u s tria l hygiene study with h is to r ic data fo r the f a c i l i t y studied, midget impinger samples were also co lle c te d fo r selected jobs in a manner s im ila r to past sampling techniques. Breathing zone impinger samples were co lle c te d in ethyl alcohol at a flow rate o f 0.1 cubic fe e t per minute with sampling periods ranging from 15 to 30 minutes. These samples were counted at the end of each work s h if t using Dunn counting c e lls and b rig h t f ie ld optical microscopy (lOOx). Two preparations were made fo r each sample and allowed to stand fo r 30 minutes p rio r to counting. P a rtic le counts were made by two experienced counters, and new preparations were made and samples recounted, i f counts d iffe re d by more than 10 percent. RESULTS Product Samples Results o f the X-ray d iffr a c t io n and petrochemical microscopic analyses of bulk t a lc product samples co lle c te d during the study are shown in Table 1. Talc product samples were found to contain 14 to 48 percent mineral t a lc , 37 to 59 percent trem olite and 4.5 to 15 percent an th op h yllite. A ll samples were found to contain 10-15 percent serpentines ( liz a r d it e and a n tig o rite ) and less than 2.6 percent free s i l i c a . C a lc ite and dolomite were also present in trace q u a n titie s. Trace metal analyses o f t a lc product samples are shown in Table 2 and major components analyses are shown in Table 3. A ll trace metals except iron and manganese were e s s e n tia lly absent. Iron and manganese le v e ls were also very low (<0.02 percent). As seen in Table 3, a ll ta lc s were found to have a high CaO content which co rre la te s with the observed high trem olite content. Except fo r traces o f c a lc it e , other carbonates were absent or n e g lig ib le in these ta lc s as demonstrated by low CO2 values (18). The Fe and Mn analyses in Table 3 are consistent with the resu lts shown in Table 2, and a ll major element analyses are in basic agreement with re su lts obtained by Ross et a l. (19) and by Dreessen (20) fo r ta lc s in the Gouverneur, New York area. Ross et a l. (19) also suggested that an ad dition al manganese-rich amphibole, t ir o d it e , may be found in trace q u a n tities in these deposits. While the major element analyses shown in Tables 1, 2, and 3 show 0.12 to 0.22 percent MnO, no manganese-rich amphiboles were detected by the electron microscopy analyses 6 using selected area electron d iffr a c t io n and microchemical a n a ly sis. Typical electron micrographs of fib e rs observed in the bulk samples are shown in Figures 1 and 2. Examples of ty p ic a l electron d iffr a c t io n patterns and X-ray spectra fo r the trem olite and an th op h yllite fib e rs observed in these products . are also shown in these fig u re s . These analyses have shown that most o f the long, th in fib e rs in these ta lc s are low iron a n th op h yllite w hile trem olite fib e rs tend to be shorter and have smaller aspect ra tio s (length/width). A ir Samples Tabular summaries o f TWA exposures by job category fo r the mine and m ill under study are given in Tables 4 and 5, resp ectiv ely, and more d etailed summary s t a t is t ic s concerning these data are given in Appendix I. As shown in Tables 4 and 5, free s i l i c a exposures were found to be very low. The highest TWA free s i l i c a exposure observed was 0.040-mg/m3, which is below the 8-hour TWA exposure value o f 0.05-mg/m3 recommended by NIOSH fo r th is material (16). Respirable dust exposures ranged from 0.25 to 2.96-mg/m3. No re sp ira b le dust standard has been determined fo r the mineral t a lc or t a lc containing fib ro u s trem o lite or anthophyllite; however, these concentrations are w ell below the OSHA lim its fo r nuisance dusts (21). TWA breathing zone impinger concentrations ranged from 0.5 to 15.8 m illio n p a rtic le s per cubic fo ot of a ir (mppcf) with highest concentrations being observed in the mine. The present OSHA and MSHA standard fo r "ta lc" containing less than 1 percent free s i l i c a and no asbestos fib e rs is 20 mppcf (21). Only one o f the 32 impinger samples exceeded 20 mppcf. However, since t h is t a lc contains asbestiform m aterial th is standard is not relevant to these exposures. TWA exposures to asbestos fib e rs greater than 5-pm in length exceeded 5 fib e r s per cc fo r three of s ix job categories sampled in the mine and fo r 6 o f 18 job categories sampled in the m ill. In ad dition , 17 of the 24 job categories sampled had TWA exposures exceeding the current OSHA standard o f 2.0 fib e rs less than 5-ym in length/cc. Exposures in excess of the MSHA and OSHA allowable c e ilin g value o f 10 fib e rs less than 5-ym in length/cc were observed in 9 of 24 job categories sampled. A summary o f TWA airborne fib e r concentrations as determined by a n a ly tic a l electron microscopy is given in Table 6 . In the mine, concentrations o f p o s itiv e ly id e n tifie d fib ro u s amphiboles ( a ll lengths) ranged from 9.5 to 17.5 fib e rs / c c whereas concentrations in the m ill were somewhat higher ranging from 9.9 7 to 70.6 fib e rs / c c . These concentrations represent minimum estimates of true amphibole fib e r exposures since many true amphibole fib e rs may not give id e n t ifia b le electron d iffr a c t io n patterns. The concentrations found using electron microscopy are fa r in excess o f those obtained by the o p tica l microscopy as fib e rs less than 5-ym in length are included in the electron microscopy re s u lts , but not in those from o p tica l microscopy. A summary of airborne fib e r types as determined by electron microscopy is shown in Table 7. In the mine, 38 percent o f a ll airborne fib e r s were a n th o p h y llite , 19 percent were trem olite, and 39 percent were u n id e n tifie d . In the m ill, 45 percent of a ll fib e r s were anthophyl1it e , 12 percent were trem olite, and 38 percent were u n id e n tifie d . Three percent of the fib e rs in the mine and 2 percent in the m ill gave c h ry s o tile electron d iffr a c t io n patterns. Approximately 65 percent o f the airborne fib e rs longer than 5-ym in length were id e n tifie d as an th op h yllite w hile only 7 percent were trem olite. The presence of c h ry s o tile in the a ir samples is consistent with the resu lts o f the NIOSH bulk sample analyses where trace q u an tities of c h ry s o tile were noted in some samples. A ll of the c h ry s o tile fib e rs observed in the a ir samples were less than l - ym in length. Nearly a l l of the serpentine minerals id e n tifie d in the bulk samples are liz a r d it e . Results o f airborne fib e r size determinations (diameter and length) fo r trem olite and an th op h yllite fib e rs are shown in Tables 8 and 9 with appropriate summary s t a t is t ic s . As expected, trem olite fib e rs tended to be larg er in diameter and shorter in length than an th op h yllite fib e rs . The size d is trib u tio n s fo r these minerals were s im ila r fo r the mine and m ill. Median fib e r diameters o f 0.19 and 0.13-ym were observed fo r trem olite and a n th o p h yllite , resp ectiv ely. In the mine, median fib e r lengths o f 1 .6-ym fo r trem olite and 1.5-ym fo r an th op h yllite were observed. S im ilar lengths were seen in the m ill. In the mine and m ill, only 3 percent of the trem olite fib e rs were longer than 5-ym whereas 8-10 percent of the anthophyllite. fib e rs were longer than th is length. Median aspect ra tio s (length to width) of 9.5 and 7.5 were observed for an th op h yllite and trem olite, re sp e ctiv e ly , as shown in Table 10. Only 30 percent of the trem olite fib e rs had aspect ra tio s greater than 10 to 1 whereas 48 percent o f the an th op h yllite fib e rs had aspect ra tio s greater than th is value. These fib e r size c h a ra c te ris tic s are sim ila r to those observed in other in d u s tria l operations processing asbestos fib e rs (22). Typical electron photomicrographs o f airborne p a rticu la te s from the mine and m ill are shown in Figures 3, 4, and 5 . The 8 asbestiform nature o f these fib e rs may be fu rth er demonstrated by observations of th e ir f i b r i l structures. COMPARISON OF PAST AND PRESENT EXPOSURES The present studies demonstrate elevated exposures to asbestiform minerals in nearly a ll mine and m ill process operations. Comparisons between present dust (mppcf) and fib e r ( fib e rs > 5-ym in length/cc) exposures and h is t o r ic exposure measurements are shown in Tables 11 and 12, re sp e ctiv e ly . These data are gathered from a number o f sources (11, 23-33). Trends in dust concentrations as a function of calendar time are d i f f i c u l t to in te rp re t fo r several reasons. Of primary importance is the re la tiv e paucity of data on some operations p rio r to 1970. Secondly, very few samples were taken in any given year, therefore the representative of these samples is unknown. To illu s t r a t e trends in dust concentrations, average yearly values fo r mine and m ill operations were calcu lated and are shown in Figures 6 and 7, re sp e ctiv e ly . Figure 6 shows no consisten t trends in dust concentrations when a l l mine operations are considered. On the other hand, the mine exposures fo r such operations as d r i l l in g , dragline loading, tramming, and mucking show r e la t iv e ly consistent exposure leve ls over time with only s lig h t d eviation s. This might be expected since wet d r illin g has been a routine p ra ctice . In ad dition, ores being mined are r e la t iv e ly wet. Primary crushing and hoist loading operations show a s lig h t ly decreasing trend. Controls such as water sprays fo r dust suppresion at the primary crusher are the most probable explanation fo r th is trend. A greater trend of decreasing dust concentrations in m ill operations is demonstrated in Figure 7 fo r a ll m ill operations combined. Figure 7 also shows a more pronounced decreasing trend in exposure when the uncontrolled operation o f loading bagged t a lc in to box cars is excluded form the calcu lated yearly averages. Engineering co n tro ls fo r t a lc m illin g operations have improved with time. As shown in Table 12, fib e r exposure measurements have only been made since 1970. Results of the 1975 NIOSH survey tend to show a recent reduction in fib e r exposure when contrasted with e a r lie r data fo r most operations. Radon daughter measurements have been made in the mine under study by the Mining Enforcement and Safety Adm inistration 9 (MESA). Measurements taken in 1973 and 1976 showed only n il to trace le v e ls (34, 35). COMPARISON OF EXPOSURE CHARACTERISTICS WITH OTHER TALC MINES AND MILLS IN THE GOUVERNEUR, N.Y. AREA Throughout the years, a number o f d iffe re n t companies have operated t a lc mining and m illin g operations in the Gouverneur Talc D is t r ic t . In ad dition , past health e ffe c ts studies of workers in these m ills have generally considered exposure c h a ra c te ris tic s between the various operations in th is area to be s u b s ta n tia lly the same. The company under study, however, maintains that ores from various mines in the area are not the same, with some containing asbestos w hile others do not. The company fu rth er maintains that ores from another nearby operation do contain an th op h yllite asbestos w hile ores from the mine and m ill which is the subject of the present study do not contain asbestos fib e rs. In order to compare airborne exposure ch a ra c te ris tic s between these two operations, 10 airborne dust samples co lle c te d by MESA in the mine and m ill acknowledged as containing asbestos were obtained. These samples were analyzed fo r airborne fib e r c h a ra c te ris tic s using a n a ly tica l electron microscopy (a n a lytica l methods previously described). Results of these studies and comparisons with data from the mine and m ill studied by NIOSH and maintained, to be asbestos free by the company, are shown in Table 13. The data shown in Table 13 demonstrate that exposure c h a ra c te ris tic s between the two operations are su b s ta n tia lly the same. In fa c t, the airborne dust samples from the mine and m ill studied by NIOSH and maintained by the company to be asbestos free were found to contain a higher proportion o f p o s itiv e ly id e n tifie d asbestiform amphiboles la rg e ly due to a higher trem o lite content. A ll other fib e r c h a ra c te ris tic s , such a median length, diameter, aspect r a t io , and proportion < 5-um in length, were not s t a t is t ic a lly d iffe r e n t at the 0.05 level (36). 10 REVIEW OF HEALTH EFFECTS FROM EXPOSURE TO TALCS CONTAINING ASBESTIFORM AND ASSOCIATED MINERALS What are the known health e ffe c ts o f ta lc ? Inhalation by children o f large doses of t a lc have resulted in an inflammatory pulmonary response leading to death in some cases (37, 38). The acute symptoms are i n i t i a l s lig h t re sp ira to ry d is tre ss increasing a fte r four to s ix hours and accompanied by cough, tachycardia, and cyanosis. Autopsy revealed b ro n ch itis and acute b r o n c h io lit is with pulmonary edema, fo cal a te le c ta s is , and emphysema. A liv is a t o r reported the rapid development of t a lc o s is in eight workers between 16 and 60 months a fte r f i r s t exposure in an in d u s tria l s e ttin g (39). The rapid development and progression was attrib u ted to the high concentration of ta lc p a rtic le s less than 50-um in size as w ell as the high s ilic a t e content. Most o f these anecdotal reports have included l i t t l e ch aracterization of the ta lc s involved. RESPIRATORY MORBIDITY STUDIES Three patterns o f in f ilt r a t io n on chest X-ray among those exposed to t a lc have been described: (1 ) nodular -- d iscrete o p a citie s 3-5 mm, sim ila r to s i l i c o s i s and favoring the mid-lung f ie ld s ; (2 ) d iffu s e -- in t e r s t it ia l fib r o s is s im ila r to asbestosis and favoring the lower lung zone; (3 ) mixed -- both types present (40). This varied type of X-ray pattern has been a ttrib u ted to the heterog en icity o f t a lc (40). Although changes suggestive of s i l i c o s i s were observed in some instances, in general X-ray changes were s im ila r to those seen in asbestosis (9, 10, 41). More than four decades have elapsed since the f i r s t epidem iological data were published demonstrating adverse health e ffe c ts o f trem olite ta lc exposure. In 1933, Dreessen (20) published the resu lts o f a chest X-ray study of 57 workers engaged in the mining and m illin g o f ta lc s containing up to 45 percent trem olite and l i t t l e free s i l i c a . This study showed that a ll workers with greater than 10 years exposure had increased lung markings ranging from increased fib r o s is to what was termed "second stage" pneumoconiosis. Among these 17 workers, no cases of active tu b ercu lo sis were observed. Dreessen stated that the observed pneumoconiosis had not led to d isa b ility . The re sp ira to ry e ffe c ts o f exposure to t a lc containing 10 percent "bladed" trem olite in two Georgia t a lc mines and m ills were reported by Dreessen and D alla V a lle in 1935 (42). A to ta l 11 of 66 workers were given physical examinations and chest X-rays o f which 19 were exposed fo r more than 10 years with only 2 having 20 or more years o f exposure. Twenty-two o f these workers demonstrated pneumoconiosis with varying sev e rity . Approximately h a lf o f the m ill workers exposed to an average dust concentration of 300 mppcf were diagnosed as having pneumoconiosis with eight having frank symptoms such as dyspnea, cough, chest pain, ra le s , and fin g e r clubbing. Examination of nine former t a lc workers who had been separated from exposure more than 3 years demonstrated pneumoconiosis in a l l cases with four cases in advanced stages causing these authors to conclude that the lung changes were permanent. Many o f the health e ffe c ts studies on in d iv id u a ls exposed to t a lc have been done in New York in the same areas as th is study (Table 14). The exposures were generally quite high. These studies in d ica te that exposed t a lc workers report increased subjective complaints o f dyspnea and cough. Physical fin d in g s include diminished breath sounds, ra le s , rhonchi, wheezing, c re p ita tio n s , and clubbing. Pulmonary function measures suggest a r e s t r ic t iv e disease with reduced tran sfer capacity (DIqq). In addition to these fin d in g s , radiographic changes in the chest have also been noted, although the fin d in g s have not been reported in ILO/UC nomenclature. These include f ib r o s is and pneumoconiosis, p rim a rily reported as pulmonary in f ilt r a t e s o f grade 0, 1, 2, and 3. The grading of pulmonary in f ilt r a t e s involves a re tic u la te d appearance in the lower lung f ie ld s (grade 1), reticu lon od ular i n f i l t r a t io n involving approximately 50 percent o f the to ta l lung area (grade 2), and a more d iffu s e reticu lon od u lar in f ilt r a t io n involvin g more than 50 percent of the to ta l lung (grade 3) (10). Case studies o f New York trem olite t a lc workers were f i r s t reported by Porro et a l. (43). F ifte e n pneumoconiosis deaths in t a lc workers were studied in addition to fiv e autopsy studies. Thirteen o f these deaths were considered to be d ir e c t ly a ttrib u ta b le to the pneumoconiosis thus confirming the d isa b lin g character o f th is exposure. These authors concluded that the d is a b lin g tissu e changes were due to trem olite t a lc exposure. Some c la s s ific a t io n s were noted. Siegal e t a l. (44, 45) reported a study of roentgenological fin d in g s among New York t a lc workers in addition to an assessment of th e ir exposures. These ta lc s were described as containing fib ro u s trem olite and an th op h yllite and less than 1 percent free S i02- A to ta l o f 221 t a lc workers in three mines and f iv e m ills were given chest X-ray examinations. Of the 221 12 men examined, 32 showed marked fib r o s is . Those workers with 10 or more years employment demonstrated an incidence of f ib r o s is o f 29.9 percent whereas those employed fo r more than 30 years had a fib r o s is incidence of 74 percent. This fib r o s is was described as d isab lin g and often accompanied by dyspnea, cough, and fa tig u e . "Talc plaques" were id e n tifie d in 6.3 percent of the workers examined. These authors described the fib r o s is observed as resembling that seen among asbestos workers. The 32 cases o f pneumoconiosis id e n tifie d by Siegal et a l. (44, 45) were follow ed prospectively by K le in fe ld et a l. (46). In the 14 year period a fte r the Siegal study, 19 o f the 32 workers died with the ages of death ranging from 48 to 84 years. Four o f these 19 deaths were believed to be d ir e c t ly a ttrib u ta b le to t a lc pneumoconiosis. One death due to pleural mesothelioma was reported. Medical examinations o f the 13 liv in g workers were performed includ ing a physical examination, chest X-ray, EMG, and peripheral blood studies (Hgb, RBC, WBC, d if f f e r e n t ia l count). Dyspnea of such se v e rity as to lim it ordinary physical a c t iv it y was found in a ll workers. Moderate to severe progression of lung X-ray fin d in g s were seen in 10 of these workers and " ta lc plaques" were seen in a ll but one worker. Six out of 11 demonstrated an abnormal electrocardiogram . Peripheral blood fin d in g s were not considered to be of s ig n ific a n c e . These authors also reported the presence of "asbestos bodies-" h is t o lo g ic a lly . Sim ilar fin d in g s were reported in a la t t e r study of s ix pneumoconiosis cases with autopsy studies (41). A comparative c lin ic a l and environmental study o f workers exposed to fib ro u s and nonfibrous ta lc s in New York was reported by Messite et a l. (7). Three t a lc operations in St. Lawrence County (fibrous ore formations) and one operation in Lewis County (nonfibrous ore formations) were selected fo r study and a to ta l of 229 workers were given physical examinations and chest X-rays. Among miners, the incidence o f pulmonary fib r o s is was low fo r both the St. Lawrence and Lewis County cohorts; however, the mean duration o f exposure was only 12.7 and 10.3 years, re sp e ctiv e ly . Anong m ille r s , the incidence o f f ib r o s is was 12.2 percent and 4.3 percent, re s p e c tiv e ly , fo r the St. Lawrence and Lewis cohorts. Exposure le v e ls in the plant were described as being s im ila r with a l l ta lc s having a low free s i l i c a content. These authors concluded that both types of t a lc were capable of producing pulmonary f ib r o s is although the trem olite ( fib ro s is ) v a rie ty was more pathogenic. In ad dition , these in v estiga to rs stated that no cases o f fib r o s is were found in m ille rs o f e ith e r t a lc v a rie ty whose average exposure was less than 20 mppcf or whose duration o f exposure was less than 10 years. 13 In a follow -up study, K le in fe ld et a l. (8 ) made addition al comparisons, includ ing lung fu nction, between the St. Lawrence and Lewis County, New York, cohorts described above. T h irty workers exposed to fib ro u s ta lc s and 13 exposed to nonfibrous ta lc s were given chest X-ray and pulmonary function tests. Dyspnea was present in 16 of 30 workers in the fib ro u s t a lc exposed group and in 6 o f 13 in the nonfibrous ta lc exposed group. Abnormal auscultatory fin d in g s (ra les, rhonchi, wheezing) were found in 8 o f the 30 workers and 6 o f the 13 workers exposed to fib ro u s and nonfibrous t a lc , resp ectiv ely. The incidence o f pulmonary in f ilt r a t io n as seen in chest film s was 13 of 30 fo r the fib ro u s group and 3 of 13 fo r the nonfibrous group. Both groups showed pulmonary function changes with 4 of 13 workers in the group exposed to nonfibrous t a lc and 14 o f 30 workers in the group exposed to fib ro u s t a lc showing s ig n ific a n t ly reduced v it a l capacity. Exposures to both groups were reported to be considerably in excess o f 20 mppcf. K le in fe ld et a l. (12) studied the lung function of 16 trem olite t a lc workers who ranged from 39 to 69 years o f age (mean age 54.8 years). A ll had been exposed to t a lc dust in m illin g operations fo r 10 or more years and had no previous occupational dust exposures. C lin ic a l examinations of the 16 workers showed 14 had dyspnea on exertion; 10 ra le s or wheezing; and 6 clubbing of the fin g e rs . Increased pulmonary i n f ilt r a t io n was noted in 5 o f the 16 workers. The lung function studies showed 7 o f the 16 to have reduced v it a l cap a citie s and one worker was found to have a lung function consistent with r e s t r ic t iv e lung disease. The mean duration of exposure fo r the 16 workers was 20.4 years and the mean weighted average exposure was reported to be 68.9 mppcf. Thirteen of the 16 workers studied gave a p ositive smoking h isto ry (30 cig arettes per day fo r a minimum o f 5 years). In a subsequent study, K le in fe ld (10) performed sim ila r studies as those described above among a group o f 43 trem olite ta lc workers and 41 unexposed co n tro ls of s im ila r age and smoking h is to ry . In the t a lc cohort, 29 had dyspnea versus only 2 in the control population. Eleven t a lc workers gave a h isto ry of chronic cough and 8 t a lc workers showed fin g e r clubbing whereas no clubbing or cough was noted among co n tro ls. Sixteen of 43 t a lc workers had p o sitiv e X-ray fin d in g s of pulmonary i n f ilt r a t io n versus none in c o n tro ls, and reduced v it a l capacity was also found in 13 t a lc workers and one co n tro l. These ta lc workers were reported to have a mean exposure duration of 19 years and weighted average exposure of 62.3 mppcf. A study of chest X-ray fin d in g s and c lin ic a l symptoms among miners and m ille rs at the t a lc mine and m ill under study was 14 reported by K le in fe ld et a l. (11). Th irty-n in e workers with a mean exposure of 16.2 years (range 11-22 years) were examined in addition to 41 co n tro ls who liv e d in the same geographic area and who were of the same sex and mean age but had no occupational dust exposure. Dyspnea was present in 23.1 percent of the t a lc workers versus 7.3 percent of the c o n tro ls, a fin d in g s im ila r to that seen in an th op h yllite asbestos workers (47). One worker studied was said to have ra d io lo g ic fin d in g s compatible with pneumoconiosis, whereas no cases were found among c o n tro ls. The authors suggested that t a lc containing trem o lite and an th op h yllite may be less fib ro g e n ic than ch ry s o tile and amosite asbestos at s im ila r exposure le v e ls and exposure duration; however, these authors did not preclude the possible existence of pneumoconiosis among these workers since no lung function studies were conducted. The importance of su blig ht m icroscopic asbestos fib e rs in asbestosis has re ce n tly been reported (48, 49, 50) and brings in to question the concept that only fib e rs greater than 5 microns in length are pathogenic in t a lc o s is (51). In a patient with t a lc pneumoconiosis, M ille r et a l . , (48) were unable to detect t a lc by h is to lo g ic a l techniques using lig h t microscopy. The presence of t a lc was established by X-ray d iffr a c t io n and electron microscopy. Most p a rtic le s were less than 0.5 micron in length, and therefore, below the lim it o f resolu tion of the lig h t microscope. The question o f the s it e o f e a rly changes in the human lung a fte r exposure to t a lc has not been very well investigated. Seeler et a l. (52), claimed that the e a rlie s t change involving the lung parenchyma in two cases of t a lc pneumoconiosis was a fib ro u s thickening of the alveolar w alls. K le in fe ld et a l. (41), noted deposition of ferruginous bodies in the re sp ira to ry bronchioles. The e a r lie r studies o f t a lc workers in the New York area v a ria b ly reported the presence of pleural plaques and pleural d e n sitie s (41, 44, 45, 46). The pleura o f men exposed to ta lc are often found on autopsy to have dense f ib r o s is thickening (41, 48, 52, 53). P e rica rd ia l c a lc if ic a t io n has also been observed (54). Pleural thickening is associated with symptoms and a decreased pulmonary function; pleural plaques are not (55). Pleural thickening may also have a poorer prognosis (56). Pleural thickening and c a lc if ic a t io n s are a very common radiographic fin d in g in asbestosis and in d iv id u a ls exposed to asbestos, and may be more common than fib r o s is (56, 57, 58, 59, 60, 61). The prevalence of pleural changes is higher where there is exposure to an th op h yllite (55, 62). Not a ll pleural changes, however, are n ecessa rily related to asbestos exposure (63). 15 MORTALITY STUDIES Although a number o f the studies described above have 11 demonstrated the presence of pneumoconiosis among trem olite t a lc miners in New York, these study designs were in s e n s itiv e to detection of carcinogenic r is k s . However, two retrospective proportional m orta lity studies have demonstrated an increased ris k of m o rta lity due to cancer of the lung and pleura among these workers (5, 6 ). An i n i t i a l study by K le in fe ld et a l. (6 ) included 220 t a lc miners and m ille r s employed in 1940 who had 15 or more years exposure between 1940 and 1965. Among t h is cohort there were 91 deaths of which 10 (11 percent) were due to malignancies o f the lung or pleura, whereas only 2.9 (3.2 percent) were expected. In a d d itio n , 28 deaths were due to pneumoconiosis or it s com plications. One o f the resp irato ry cancers was a fibrosarcoma of the pleura. In a subsequent follow -up study, K le in fe ld et a l. (5) extended the period of observation of the previously studied cohort from 1965 to 1969. This updated cohort consisted of 260 workers among which there were 108 deaths. Thirteen of these deaths (12 percent) were due to re sp ira to ry cancer, whereas only 4 (3.7 percent) were expected. Twenty-nine deaths were due to pneumoconiosis or it s com plications. These authors analyzed m o rta lity patterns by 5 year in te rv a ls between 1940 and 1969 and concluded that the re sp ira to ry cancer ris k approached expected values a fte r the period 1960-1964. The v a lid it y of th is conclusion must be questioned since an analysis o f m orta lity in re la tio n to cancer latency was not undertaken. Indeed, during the ad dition al 9 years of observation, 17 deaths were observed o f which 2 (12 percent) were re sp ira to ry cancers, observations sim ila r to previous fin d in g s. In ad dition , the lim ita tio n s of proportional m o rta lity studies in the presence of an elevated pneumoconiosis ris k are now w ell known. An excess cancer ris k has been demonstrated among workers exposed to an th op h yllite asbestos (47, 64, 65). Nurminen (65) reported on the m o rta lity experience of an th op h yllite asbestos workers in Finland. This study included 1,030 workers who had been employed fo r 3 months or more from 1936 to 1966 and follow ed u n t il 1968. Expected cause s p e c ific deaths were calcu lated using Finland national rates fo r 1951-1964. There were 224 deaths in t h is cohort whereas 204 were expected. The mean age at death fo r the cohort was 53.4 years. Twenty-five deaths (12 percent) had asbestosis as an underlying cause, and there was also a highly s ig n ific a n t excess ris k of resp irato ry cancer (13 obs. versus 6 exp.; p<0.01). No mesotheliomas were 16 detected. The mean latency between f i r s t exposure and death due to asbestosis was 19 years. One o f the most comprehensive studies o f m o rta lity and m orbidity among an th op h yllite asbestos workers was reported by Meurman et a l. (47) and K aviluto et a l. (64). A cohort of 1,092 workers who had worked at least 3 months between January 1936 and June 1967 was obtained from two mining operations; one of which produced mainly trem olite t a lc . For ca lcu la tio n of expected age and cause s p e c ific deaths, proportional rates fo r Finland were used fo r 1958 which was the median year of death fo r these workers. In ad dition , a control group matched fo r date o f b irth and sex was chosen from a lo ca l population re g is try . Of the 1,092 employees, 248 deaths were observed. Thirteen deaths due to asbestosis were observed fo r the cohort and none in the co n tro ls. Twenty-one lung cancers were observed in the worker cohort versus 13 in the control group. The most s ig n ific a n t cancer r is k was observed in those with 10 or more years of exposure. These authors adjusted lung cancer rates fo r smoking habits and concluded that a nonsmoking asbestos worker has a re la tiv e risk of 1.4 whereas the smoking asbestos worker had a re la tiv e r is k o f 17.0. No cases of mesothelioma were reported. A ll of the above studies of workers exposed to t a lc containing fibrous trem olite, fibrous anthophyllite or anthophyllite _ asbestos have demonstrated an excess ris k of both pneumoconiosis and re sp ira to ry cancer. L i t t l e evidence of an excessive ris k of mesothelioma among such exposed workers has yet been demonstrated; however, an excessive incidence o f pleural changes includ ing pleural thickening and c a lc if ic a t io n s has been observed in chest film s . 17 CROSS-SECTIONAL MORBIDITY STUDY A cross-sectional m orbidity study was in it ia t e d to examine a ll presently employed workers in th is t a lc mine and m ill. The study was designed to answer the fo llo w in g questions regarding chronic e ffe c ts o f exposure: 1) Is there an increased prevalence o f abnormal health e ffe cts (e.g., symptoms, decreased pulmonary function) in workers exposed to t a lc when compared to other in d u s tria l populations? 2) I f there are detrimental e ffe c ts o f exposure, what are the dose-response relations? DESCRIPTION OF WORK FORCE The present work fo rce consists of approximately 156 male m ille r s and miners, 35 of whom had worked at other t a lc mines. One hundred and twenty-one (78 percent) p articip a te d in the study. The average fo r years of t a lc exposure is 10.2 years fo r the study population, and 10.5 years fo r the nonparticipants. The p a rtic ip a tio n rate among the d iffe r e n t work areas is s im ila r. MATERIALS AND METHODS A modified Medical Research Council re sp ira to ry questionnaire containing questions on to ta l work and smoking h isto ry was administered by trained interview ers. Standard PA and la te ra l chest X-rays were taken and read by three readers using ILO/UC scheme. Flow volume curves from a minimum o f fiv e forced re sp ira to ry maneuvers were obtained and recorded on magnetic tape using an Ohio 800 r o llin g seal spirometer. The maximum values from the curves were used fo r an alysis. Lung fu n ctio n , the prevalence o f symptoms and radiographic fin d in g s in th is population were compared with those from 9,347 coal miners from the second round o f the National Coal Study, and 1,095 potash miners examined by NI0SH in the Study of the E ffe cts o f Diesel Exhaust in Non-Coal Miners. Individuals in each control population were grouped in to s im ila r age (10 year in te rv a ls ), height (10 cm in te rv a ls ), smoking (nonsmoker, ex-smoker, and smoker), and years in mining (<15 years, 15 years) categories. The expected prevalence of symptoms and radiographic fin d in g s in coal and potash workers were calculated by using the rates in each category of the comparison populations and m u ltip ly in g them by the number of in d iv id u a ls in the same categories o f the t a lc population. P re d ictiv e 19 equations re fle c t in g the e ffe c ts o f age and height were ca lcu la te d fo r each smoking/years worked category of coal and potash miners. Each t a lc worker's lung function was then compared to predicted values obtained from the appropriate category in the comparison population. A ll comparison o f ta lc worker's lung function with expected lung function was summated and m u ltip lie d by 100 to give the mean percent predicted lung fu nctio n. For FEVi percent, the d iffe re n ce between observed and expected +100 was used. Dose was calcu lated in three ways: (1) Years o f exposure is simply the number of years worked at the plant under study; (2 ) Cumulative exposure was calcu lated by m ultiplying (a) present exposure in each job as determined by personal sampling ( fib e rs / c c , mg/m3) times (b) the time spent in that job (years), and then by summing a l l the exposure scores. The re s u lts fo r each in d iv id u a l are expressed as fib e r-y e a rs/cc fo r cumulative fib e r exposure and mg-years/m3 fo r re sp irab le p a rtic u la te exposures. As past environmental exposures are not w ell defined, and in some jobs exposures were greater in the past than at present (e sp e cia lly in the m ill) these estimates of cumulative exposure are lower than actual exposures; (3) The re la tio n of average time spent in each job was examined in workers with and without p leural thickening over the to ta l work h isto ry om itting the most recent 10 years. RESULTS The age-smoking d is trib u tio n o f the 93 t a lc workers whose t a lc exposure was only at the mine and m ill being studied is shown in Table 15. Almost h a lf are cig a re tte smokers with s lig h t ly more ex-smokers than nonsmokers. Almost 2/3 of the nonsmokers are less than 30, and over 3/4 o f the ex-smokers are 40 years o f age or more. Smokers are more evenly d is trib u te d in a l l age groups, although the percentage o f smokers is highest in the 30-39 year age group. The d is trib u tio n is very s im ila r fo r a ll 121 workers (Table 15A). Table 16 shows the d is trib u tio n o f years worked in t a lc , and cumulative p a rtic u la te and fib e r exposures by age. Except fo r the group over 60 years old where there are only two in d iv id u a ls , there is a consistent and approximately equal increase in a ll three exposure parameters with increasing age. A s im ila r re la tio n sh ip of exposure with age is observed fo r a ll 121 workers (Table 16). Tables 17 and 17A summarize the d is trib u tio n o f symptoms and radiographic fin d in g s by smoking h ab its. Smokers have a higher 20 prevalence o f cough, phlegm, hemoptysis and shortness o f breath, with symptoms markedly lower among nonsmokers. The d ifferen ces are also s t a t is t ic a lly s ig n ific a n t fo r cough and phlegm. Cigarette smoking shows no apparent association with pleural thickening. There are two cases of c a lc if ic a t io n and four of irre g u la r o p a citie s, but the numbers are too small to analyze fo r dose-response re la tio n s. Tables 18 and 18A summarize the association o f age with symptoms and radiographic fin d in g s . Age (and therefore, long-term exposure) shows no d is c e rn ib le association with symptoms. The higher prevalence of cough and phlegm in the 30-39 year age group is probably a re fle c tio n o f the high proportion o f smokers in the category. Likewise, the s lig h t ly higher prevalence of dyspnea in the 30-39 and 50+ year age group is also probably due to the re la tiv e proportion of smokers and ex-smokers in those ages. P leural thickening, on the other hand, is not found in the age groups less than 40 (mean of 14 years exposure), and is highest in the 50-59 (mean o f 20 years exposure) and greater than 60 year (mean of 28 years exposure) age groups. In Tables 19 and 19A the prevalence o f symptoms and radiographic fin d in g s are compared with coal and potash workers c o n tro llin g fo r age, height, smoking h abits, and years worked. Among the t a lc workers employed only at the mine and m ill under study fo r less than 15 years, the reported symptom prevalences o f cough and phlegm are not s ig n ific a n t ly higher than those of coal and potash workers. In the group of workers with more than 15 years experience, there is no s t a t is t ic a lly s ig n ific a n t d iffe re n ce in the prevalence o f (a) hemoptysis in t a lc workers compared to coal and potash workers; (b) cough in t a lc workers compared to coal workers; and (c) phlegm in t a lc workers compared to potash workers. Coal miners with more than 15 years experience have higher prevalence of phlegm and dyspnea than do t a lc workers, while cough and dyspnea is higher in these ta lc workers than in the potash workers. These d ifferen ces are not s t a t is t ic a lly d iffe re n t. The prevalence o f radiographic abnorm alities is less than two percent in a l l groups with less than 15 years worked. The rates are higher in the greater than 15 year groups, but there are no s ig n ific a n t d ifferen ces in the prevalence of regular op acities between the t a lc and comparison groups. In the t a lc workers with no previous t a lc exposure, pleural c a lc if ic a t io n is 0 21 nercent in those with less than 15 years worked and 3.4 percent in those w ith more than 15 years worked (one case), w h ile rvisiiv>ai t h i rkpni na is 1.6 percent and 31.0 percent . ie s S e c t iv e li This compares to a rate fo r pleural t h i c k e n in g of 0 3 percent to 1.6 percent in coal miners and 0.5 percent to 4.4 percent fn potash miners. There is no pleural c a lc if ic a t io n in the potash population, while in coal miners the prevalence is 0 percent fo r those working less than 15 years and 0.1 percent fo r those working more than 15 years. In those with more than 15 years experience, the prevalence of irre g u la r o p a citie s is 3.4 percent, 5^3 percent and 0.7 percent in t a lc , coal, and potash workers resp e ctiv e ly (Table 19). Rpnnrted svmptom rates increase s lig h t ly when a ll 121 ta lc workers are^considered (Table 19A). In the 82 t a lc workers with less than 15 years worked, cough and phlegm are higher than potash and coal workers. There i s l i t t l e d iffe re n ce in the Drevalence o f dyspnea. In the 39 t a lc workers with more than 15 years experience, reported cough is s t i l l higher than in potash workers, but is e s s e n tia lly the same as in coal miners. g is about the same in t a lc and potash workers, however,the 26 Percent phlegm reported by these t a lc workers is s ig n ific a n t ly less than the 46 percent prevalence among coal workers. Dyspnea in these t a lc workers is 23 percent which is s ig n ific a n t ly less than the 39 percent in coal workers and greater than the 13 percent in potash'workers. Among these t a lc workers, there i no unusual prevalence of hemoptysis in e ith e r category of years worked There are no d ifferences in the prevalence of radiographic abnorm alities in the group who have worked less than 15 years. In those with more than 15 years experience, pleural thickening and pleural c a lc if ic a t io n are higher in the t a lc workers than in coal and potash workers; the increased prevalence of pleural thickening is highly s t a t is t ic a lly s ig n ific a n t . Irregular o p a citie s among t a lc workers are higher than those in coal and potash workers, but *he ij c j e ^ e is s t a t i s t i c a l l y s ig n ific a n t only when compared w th that " ^ e n t workers. The prevalence of rounded o p a citie s is 3 and 2 percent ' in t a lc and potash workers re sp e ctiv e ly , but 15 percent in coal workers. Table 20 summarizes the re la tio n s h ip between cumulative exposure and pulmonary function among both groups of t a lc workers employed only at the mine and m ill under study. Using predicted values based on coal and potash workers, mean percent-of-predicted FEVi and FVC ranged from 92-95 percent. Predicted FEV percent is near 100, and peak flow is J bo^e predicted compared to coal workers, but th is is not true when 22 compared to potash workers. Mean flow rates are s ig n ific a n t ly reduced compared to both coal and potash workers. Exposure among these ta lc workers to p a rticu la te s and to fib e rs shows a s ig n ific a n t association with reduced FEVi and FVC. For example, a t a lc worker in a job with 2 mg/rrH exposure to resp ira b le p a rticu la te w i l l , on the average, experience about a 1 - 1.4 percentage point reduction/year in observed to predicted r a t io fo r FEVi and Fvc- For an avera9e exposure of 5 fib e r s / c c , the reduction is about 0.5 - 0.7 percentage points per year. FEV percent and flow rates are not s ig n ific a n t ly related to exposure, although the percentage point reduction is large fo r flows at lower lung volumes. The reductions are larg er when the comparison group is potash miners. Sim ilar reductions occur i f age or years o f employment are substituted fo r fib e r or p a rticu la te exposure because of th e ir high co rre la tio n s. These t a lc workers e m p iric a lly "age" fa ste r (experience a fa s te r reduction in the FEVi and FVC) compared to coal and potash miners. Table 21 and 21A compare age, smoking habits, and exposure h isto ry of t a lc workers with and without pleural thickening. As previously noted, smoking is not related to pleural thickening. For example, the 50-59 year group with pleural thickening has the lowest mean pack years, and the 40-49 year old group with pleural thickening has fewer average pack years than the 40-49 year old group without pleural thickening. P a rtic u la te exposure is s lig h t ly lower in the groups with pleural thickening, the average fib e r exposure on a yearly basis is the same in the groups with and without pleural thickening. In the 50-59 year age group, those with pleural thickening started working at an e a r lie r age than those without pleural thickening. In the 40-60 year age group, those with pleural thickening have reduced lung function. Past environmental exposures in each job are not n ecessa rily re fle cte d by present exposure estim ates. Exposure information is not av a ila b le fo r a ll jobs and past environmental data were la rg e ly co lle c te d using impingers rather than f i l t e r s . For these reasons time worked in d iffe r e n t jobs by workers with and without pleural thickening were compared. These data on the 93 t a lc workers employed only at the mine and m ill in th is study are summarized in Table 22. There are 9 in d iv id u a ls with p leural thickening and 20 without pleural thickening among those with greater than 15 years employment. Among those with pleural thickening, about 71 percent o f th e ir years worked were spent in seven p a rtic u la r jobs, compared to about 17 percent of these same jobs fo r those without pleural thickening. 23 To assess the s ig n ific a n c e o f pleural thickening on the health of the in d iv id u a l, symptoms and pulmonary function of a l l those with pleural thickening in th is study are summarized in Table 23. C o n trollin g fo r years employment, those with pleural thickening are s lig h t ly older than those without pleural thickening. Those with Grade 2 pleural thickening have s ig n ific a n t ly elevated rates o f cough and phlegm, but those with Grade 1 pleural thickening have rates lower than the comparable age group without p leural thickening. The prevalence o f hemoptysis and dyspnea increases with increasing grade of pleural thickening, but the increases are not large. Mean ra tio s o f observed to predicted FEV^ and FVC in Grade 1 pleural thickening is about 10 percentage points below the group without pleural thickening; there is about a 4 percentage point d iffe re n ce between Grade 1 and Grade 2 pleural thickening. Mean FEV} percent is reduced only in Grade 2 pleural thickening. Predicted peak flow and FEF25 are not related to pleural thickening. Predicted FEF50 and FEF75 are reduced by about the same proportion as FEVi and FVC fo r those with Grade 1 pleural thickening compared to those with Grade 2. DISCUSSION Any cross-sectio nal epidem iologic study of chronic e ffe c ts is beset by the problem o f se le c tiv e su rv iv a l. This study population consists only o f workers presently employed. Nonrespondents present a s im ila r problem. For example, i f a ll 35 o f the workers who did not p a rtic ip a te had had no cough or phlegm, and had p a rticip a te d , the prevalence of cough would have been reduced from 32 percent to 24 percent. S im ila rly , i f a ll 35 had reported cough and phlegm, the rate would have increased from 32 percent to 49 percent. Several methodological issues are important in in terp retin g the data. Even i f there had been 100 percent p a rtic ip a tio n instead o f 78 percent, the size o f the population would s t i l l be r e la t iv e ly small to disentangle the e ffe cts of age, years worked, and p a rtic u la te and fib e r exposure. In order to evaluate the s ig n ific a n c e o f the health fin d in g s , and to adjust fo r confounding variables o f age, height, and smoking habits in estim ating dose-response re la tio n s , comparison groups of coal miners and potash miners were selected. Although coal mining is a known health hazard, and potash mines using equipment may also present a hazard, using these mine workers as comparison populations can be j u s t if ie d in several ways. 24 1) The measurement o f lung function is not a completely standardized procedure with respect to equipment, tra in in g and p ro ficie n c y o f tech nician s, number o f t r i a l s , and ca lcu la tio n of the lung measurement. These p otential measurement errors are reduced in t h is study as these procedures were v ir t u a lly the same in the control and study populations. Comparison with previously published p red ictiv e equations (e.g., Kory, Morris) may be m isleading. For example, the NIOSH measurement of coal worker lung function tends to be higher than Kory's measurement of healthy, nonexposed populations, and is at least equivalent to M o rris's measurements of nonsmoking exposed populations -- two commonly used p red iction equations. In ad dition , p red iction equations fo r d iffe r e n t smoking categories are e ith e r nonexistent or based on small numbers, thereby making smoking adjustments impossible or of questionable v a lid it y . Since one o f our primary in terests is the e ffe cts of exposure to t a lc on pulmonary fu nction, i t is necessary to adjust fo r age and smoking habits. This is because pulmonary function generally decreases more ra p id ly in smokers than in ex-smokers and nonsmokers. Comparing smokers with nonsmokers may produce an apparent association o f exposure with age, which in fa c t may be a smoking/age in te ra ctio n (66). By comparing observed pulmonary function of smokers (ex-smokers, nonsmokers), the analysis of exposure e ffe cts is not confounded by the e ffe cts of smoking. 2) T a lc, coal and potash workers are from mining populations and are lik e ly to be s im ila r with respect to many p o te n tia lly confounding variables (e .g ., physique, socio-economic ch a ra cte ristics, education) that could affect the conclusions, but are not related to the e ffe c t o f work exposure. Using these mining comparison groups is therefore preferable to comparisons with sa la rie d workers in the same company or even local nonmining populations, fo r in the comparisons with sa la rie d or other workers there are _ problems of major discrepancies in physique, pay, education, n u tritio n and other fa cto rs that by themselves could re s u lt in differences in health status. 3) Comparing e ffe cts o f t a lc exposure with e ffe c ts from exposure to other substances w ill not co n clu siv e ly in d icate the nature o f the e ffe c ts o f the t a lc exposure but i t w ill provide re la tiv e comparisons; fo r example, i f the health of ta lc workers is worse than coal miners the differences in d ica te the t o x ic it y of t a lc as compared to coal and pinpoint s p e c ific health hazards associated with t a lc . Conversely, e ffe cts of t a lc less to x ic than coal do not 25 n ecessa rily mean there is no ris k associated with ta lc exposure, but only that t a lc workers are "better o ff" (e.g., have fewer symptoms, fewer radiographic abnormalities., etc.) than coal workers. I f t a lc workers are healthier than coal miners, they may s t i l l be less healthy than i f they were not exposed to t a lc at a l l . Although less studied than co al, a m o rta lity study of potash miners suggest that exposure to potash does not increase re sp ira to ry disease (67). Thus, the medical fin d in g s in these t a lc workers are compared with those in two mining comparison groups -- one that is thought to have l i t t l e e ffe c ts on the resp irato ry system, and one that is known to have a detrimental e ffe c t on the re sp ira to ry system. The reported re sp ira to ry symptoms in th is study group seem high fo r any healthy population. Most of those with symptoms are e ith e r smokers or ex-smokers, and many populations in the dusty trades also report s im ila r ily high symptom rates. S p e c ific a lly , the prevalence o f symptoms (except fo r dyspnea) when contrasted with coal workers is higher in t a lc workers i f length of time worked is less than 15 years, but lower i f years worked is greater than 15 years. When compared to potash workers, however, t a lc workers have higher symptom rates in both groups (except fo r phlegm and hemoptysis in the greater than 15 years group). . Table 24 compares the prevalence o f re sp ira to ry symptoms from the t a lc workers in th is study with c h ry s o tile asbestos workers in Canada. Except fo r the nonsmoking category where asbestos workers report a higher prevalence o f symptoms, the re su lts are remarkably s im ila r. When compared to synthetic t e x t ile workers, both the asbestos and t a lc workers generally have a considerably higher prevalence o f phlegm and shortness o f breath. A nth ophyllite asbestos workers cannot be compared d ir e c t ly with t a lc workers in t h is study but are included in the table fo r completeness. The greatest d iffe re n ce between the coal and potash miners and the t a lc workers is the highly s ig n ific a n t increased prevalence o f p leural thickening in the t a lc workers with greater than 15 years o f exposure. In th is group, nearly one out of every three t a lc worker has pleural thickening. Since smoking is not associated with radiographic changes and the same c r it e r ia are used, i t is possible to compare the prevalence of irregular, small o p a citie s, pleural thickening and pleural c a lc if ic a t io n in c h ry s o tile asbestos workers and the ta lc workers (Table 25). Grade 1 pneumoconiosis and pleural c a lc if ic a t io n show no s trik in g d is s im ila r it y between the asbestos and t a lc workers. 26 Pleural thickening, on the other hand, is four times higher in the t a lc workers than in the asbestos workers. P leural thickening is a common fin d in g in workers exposed to asbestos. I t should be regarded as a s ig n ific a n t in d ica to r of exposure and may occur in the presence or absence o f fib r o s is (57, 58) (Table 26). Pleural c a lc if ic a t io n occurs la t e r , as i t probably develops from the u n c a lc ifie d pleural plaque (57, 60). In in s u la tio n workers i t ra re ly occurred in less than 20 years from onset o f exposure (68). C a lc ific a t io n , p a r t ic u la r ly i f b ila t e r a l, is very useful in the diagnosis of asbestosis (57, 68), although there are other causes o f pleural c a lc if ic a t io n (e.g., p le u ris y , in ju ry fo llo w in g hemothorax, inflammatory conditions that produce pleural e ffu sio n and empyema). Pleural thickening is accompanied by a decrease in lung function, e ith e r with or without fib r o s is . This was true measuring FEV^, FVC, or flow rates as in th is and other stu dies, and fo r d iffu s in g capacity, to ta l lung capacity, residual volume in other studies (61, 69, 70). when and Except fo r peak flow and FEV percent, mean percent predicted pulmonary function is s ig n ific a n t ly reduced in the t a lc workers when compared to both coal and potash miners. This reduction is thought to be the re s u lt of occupational exposure, since adjustments are made fo r years worked and the known e ffe cts of age, height, and smoking habits on pulmonary function. Despite the association o f reduced FEV i, FVC and flow rates with fib e r and p a rticu la te exposure and years worked, in te rp re ta tio n o f these data are d i f f i c u l t . The cumulative exposure is only an index, not an actual measure of exposure. There is a suggestion from past environmental measurements that exposures in ce rta in jobs, p a r tic u la r ly in the m ill, have declined over the years. Exposure in the mine appears to be more constant. Analysis of time spent in d iffe r e n t jobs by those with and without pleural thickening shows that fo r the jobs o f mine foreman, hoistman, crusher operator, packer, packer serviceman, q u a lity control tech nician , and shipping and inventory coordinator, those with pleural thickening spent more time in these p a rtic u la r jobs than those without pleural thickening. The time spent in these jobs by those with pleural thickening is 2-5 times greater than the average time spent in a l l other jobs, and contributes to a m ajority of the time spent in a ll jobs. There is , however, no way to adequately determine actual or re la tiv e past exposure le v e ls in these jobs. 27 RETROSPECTIVE COHORT STUDY OF MORTALITY METHODS A retrosp ective cohort study was in it ia t e d to determine whether workers who have been employed at th is mine and m ill have experienced any unusual m o rta lity patterns. This study cohort was defined as a l l white (those cohort members where ra c ia l status was unknown were considered white fo r purpose o f the study, since th m ajority of t h is work force is known to be white) males i n i t i a l l y employed sometime between January 1, 1947, and December 31, 1959. This c u to ff date was selected to allow fo r a s u ffic ie n t latent period fo r any development of chronic disease. An e ffo r t was made to determine the v it a l status o f each in d iv id u a l in the cohort as of June 30, 1975, and person-years at ris k and duration of employment fo r the cohort were accumulated u n t il t h is date. V ita l status was determined through records maintained by Federal and State agencies, including the Social Security Adm inistration, state v it a l s t a t is t ic s o ffic e s , and state motor v e h icle re g is tra tio n . For those in d iv id u a ls who could not be located through these sources, U.S. Postal Mail Correction Services and other follow -up searches were used. For a ll those who were known to be deceased, death c e r t if ic a t e s were requested and causes o f death were interpreted by a q u a lifie d nosologist according to the International C la s s ific a t io n o f Diseases (ICD Codes) in e ffe c t at the time o f death and then converted to the 7th Revision of the ICD Codes. A modified l i f e tab le technique was used to obtain person-years at ris k of dying by fiv e -ye a r calendar time periods, by five-year age groups, by duration o f employment, and by number of years since i n i t i a l employment at the t a lc company. Comparison was made between the observed number o f deaths among the study cohort and the number expected fo r th is population using age, calendar time, and cause s p e c ific m o rta lity rates of the U.S. white male population. The v it a l status of 96 percent o f the cohort was confirmed (Table 27). Those with an unknown v it a l status are assumed to be a liv e as of June 30, 1975 so that the true r is k o f m o rta lity associated with exposure to t a lc is not overestimated. RESULTS A to ta l o f 398 workers meeting the study cohort d e fin itio n generated 8,733 person-years at ris k of dying. F if t y percent of the workers were employed less than one year, while less than 25 29 percent were employed fo r 10 years or more. Tables 28 and 29 illu s t r a t e the d is trib u tio n of the study population by duration of employment and by date of i n i t i a l employment. Tables 30 and 30A summarize the deaths observed from the study cohort and those expected based on death rates fo r the U.S. white male population. Although the overall observed m o rta lity is higher than expected, th is d iffe re n ce is not s t a t is t ic a lly s ig n ific a n t (p<0.05). However, several s p e c ific causes of death e x h ib it increased m o rtality. The standardized m o rta lity r a t io (SMR) (SMR = observed deaths/expected deaths x 100) is s ig n ific a n t ly elevated fo r the cause o f death category, " a ll malignant neoplasms", which is p a rtly due to the s t a t is t ic a lly s ig n ific a n t increase in bronchogenic cancer (9 obs. vs. 3.3 exp.; p<0.05). Other s t a t is t ic a lly s ig n ific a n t increases fo r s p e c ific causes o f death occurred in the categories: "nonmalignant resp irato ry disease other than influen za, pneumonia, b ro n ch itis, and acute upper re sp ira to ry in fe c tio n " (5 obs. vs. 1.3 exp.; p<0.05) and "resp irato ry T.B." (3.0 obs. vs. 0.49 exp.; p<0.05). One death due to mesothelioma was observed. Table 31 demonstrates the association between bronchogenic cancer and the time in te rv a l between the i n i t i a l date of employment and the date of death (latency). As seen, there is an increasing r is k o f bronchogenic cancer with increasing latency, a trend consistent with an occupational e tio lo g y . In ad dition , the deaths due to bronchogenic cancer have an average latency of 20 years (Table 32); a period previously observed fo r a population occup ation ally exposed to an th op h yllite and other minerals (47, 64, 65). Three ad dition al deaths due to bronchogenic cancer are known to have occurred among study members. However, these deaths occurred s h o rtly a fte r the c u to ff date (6/30/75) fo r analysis and therefore were not included as observed deaths. One in d iv id u a l worked fo r 17 continuous years at the t a lc company under study and died at the age of 50. The latency period was 24 years. Another in d ivid u al who worked fo r 2 months at the t a lc company died at the age of 54. The latency period was 27 years. The th ird lung cancer death was that o f a worker employed fo r 12 years at the company under study and 12 years previously at another New York t a lc company. He died at the age of 59 and had a latency period of 23 years. At le a st three cases of nonmalignant resp irato ry disease among study cohort members are known to have been reported to the New York State Workmen's Compensation Board. These in d iv id u a ls f i l e d workmen's compensation claims fo r: (1) pneumoconiosis, 30 chronic b ro n ch itis; (2) t a lc o s is , pulmonary emphysema, chronic b ro n ch itis; and (3) t a lc o s is , pulmonary fib r o s is . These in d iv id u a ls worked at the t a lc company under study fo r 18 years, 18 years, and 25 years, respectiv ely. DISCUSSION The re s u lts o f the present study demonstrate an excessive ris k of 273 percent due to lung cancer m o rta lity and 385 percent due to nonmalignant re sp ira to ry disease among a cohort o f ta lc workers occup ation ally exposed to both asbestiform trem olite and an th op h yllite , but to l i t t l e free s i l i c a . However, several possible confounding factors must be taken in to consideration before one can a ttrib u te th is observed m o rta lity pattern to occupational exposures received at th is t a lc mine and m ill. One such fa c to r that has been shown to be correlated with the causation of lung cancer is cig a re tte smoking. The smoking patterns are la rg e ly unknown fo r t h is cohort as is the case with most retrospective studies. However, i t has been estimated that in heavy smoking worker population, smoking alone would increase the expected lung cancer m o rta lity risk by no more than 49 percent (71). Thus, cig a re tte smoking per se is u n lik e ly to account fo r the increased bronchogenic cancer risk of 273 percent observed among these t a lc miners and m ille rs . Another fa cto r to be considered is occupational exposure among cohort members re s u ltin g from p rio r employment. Known p rio r employment among those in the study who died from malignant and nonmalignant re sp ira to ry disease are given in Table 32. Several o f these in d iv id u a ls as w ell as other members of the study cohort worked at other New York State t a lc companies located in the Gouverneur Talc D is t r ic t . Due to th is consideration in d u s tria l hygiene analyses were carried out to compare the make-up of ta lc s in a neighboring mine acknowledged as having asbestiform t a lc . These comparisons are presented in Table 13. The an alysis of amphibole fib e r c h a ra c te ris tic s between these t a lc operations showed them to be s u b s ta n tia lly the same. Thus, w hile exposure le v e ls in other t a lc companies may have been higher, a ll operations involved exposures to asbestiform amphiboles with s im ila r airborne fib e r c h a ra c te ris tic s . A ll these operations have been shown to have fib e r exposures fa r in excess o f established OSHA asbestos standards. Thus, exposures to asbestiform trem olite and an th op h yllite stand out as the prime suspected e t io lo g ic facto rs associated with the observed increase in bronchogenic cancer and nonmalignant re sp ira to ry disease among th is study cohort. 31 I Of in te re st is the fa c t that four o f nine deaths due to bronchogenic cancer in th is cohort were workers employed less than 1 year in the operations under study and only one o f these cases is known to have previous exposures to ta lc s containing asbestiform m inerals. Although t h is cohort is r e la t iv e ly small, i t appears p la u sib le that even b r ie f periods of exposure to elevated concentrations o f asbestiform minerals may be associated with an increased bronchogenic cancer r is k . Such an observation has previously been reported (72). One death due to mesothelioma is known to have occurred in the study population. This in d iv id u a l worked fo r 16 years in the t a lc operation and had 11 years previous employment in construction work. Without f u l l knowledge o f th is in d iv id u a l's exposure as a construction worker, i t is d i f f i c u l t to arrive at any conclusions regarding the e t io lo g ic ro le o f ta lc exposure from th is mine and m ill fo r th is case. Although previous studies (5, 6, 47, 64, 65) have not shown an association between exposure to asbestiform an th op h yllite or trem olite and subsequent development of mesothelioma, a study in Turkey by Baris (73) has demonstrated an increased risk of developing mesothelioma among residents o f a p a rtic u la r community exposed to asbestiform trem olite, probably from th e ir drinking water. Therefore, the possible association between exposure to asbestiform trem olite and the risk o f developing mesothelioma should be fu rth er studied by continued follow -up of these ta lc workers. 32 CONCLUSIONS AND RECOMMENDATIONS An in d u s tria l hygiene study, a cross-sectional m orbidity study, and a retrospective m orta lity study were conducted among miners and m ille r s of in d u s tria l ta lc s in upper New York. These ta lc s were shown to contain fib ro u s trem olite and an th op h yllite as major contaminants. In a d d ition , both present and past worker exposures to these fib e rs were shown to be fa r in excess of occupational exposure standards established by the Occupational Safety and Health Adm inistration (OSHA) and the Mining Enforcement and Safety Adm inistration (MESA) (now c a lle d Mine Safety and Health Adm inistration MSHA). The most s trik in g fin d in g of the m orbidity study was an increased prevalence o f pleural thickening in t a lc workers with greater than 15 years of exposure, occurring in nearly one out o f every three t a lc workers. Reduced FEV^, FVC, and flow rates were also observed a fte r adjusting fo r smoking habits. The study o f m o rta lity among the workers who began employment between 1947 and 1960 demonstrated an increased number of deaths due to bronchogenic cancer. The average latency period fo r bronchogenic cancer was 20 years. A thorough review o f the ava ila b le lite ra tu re demonstrated that fin d in g s o f the present studies are in agreement with those of other studies o f occupational groups exposed to the same or sim ila r minerals or mineral mixtures. This is e s p e c ia lly true fo r occupational exposures to an th op h yllite asbestos. These fin d in g s make i t imperative that workers from the mine and m ill studied, herein, be ro u tin e ly observed using medical su rv e illa n ce c r it e r ia established in the OSHA and MSHA asbestos standard. Furthermore, a ll provisions o f these standards should be followed during the production and subsequent use of these ta lc s . 33 Table 1 Results of X-Ray Diffraction and Petrographic Microscopic Analyses of Bulk Talc Samples Collected During Study Mineral Component Talc Tremolite Anthophyllite Quartz Calcite Dolomite Serpentines * Product A 3 1-36 ^4 0 'vl 0 2.6 1 1 10-15 Samp le Analysis , % By W e i g h t Product B Product c Product D Product E 43-48 3 0-35 33-38 35-40 ^37 ^49 ^4 3 ^38 'M .5 ^5 ^8 <0.25 <0.25 0.7 1 0 0.8 <0.5 0 0 <0 .5 <0.5 <0.5 <0.5 <0 .5 10-15 10-15 10-15 10-15 Product F 14 ^59 1 5 1 . 1 < 1 <0 .5 1 0 * Includes lizardite and antigorite . Table 2 Results of Trace Metal Analyses of Bulk Talc Samples Collected During Study* Product A B C D E F Date Collected 1 1/4/75 11/4/75 11/4/75 11/4/75 11/3/75 11/3/75 Trace Metal, PPM** Cr Co Fe Mn Ni Zn Cd 3 1 1100 1700 7 20 < 1 3 < 1 1000 840 5 19 < 1 2 2 880 1000 6 17 < 1 3 2 970 1300 7 2 0 < 1 2 3 1000 1700 5 23 < 1 3 2 900 1400 5 22 < 1 * Trace metals determined by atomic spectroscopy. ** PPM-Parts per million by weight. absorption Ma jor Components sio2 Ti2 a i 2o 3 Fe20 3 FeO MnO MgO CaO N a 20 k 2o P25 h 2 CO 2 Total 1 54.85 0.04 0.38 0.10 0.04 0.21 28.40 9.02 0.28 0.10 0.03 5 . 37 1 .35 100. 17 Results of Major Components Analy s e s of Product Talc Samples 2 54.52 0.15 0.32 0.13 0.03 0.20 28.78 8.53 0.44 0.17 0.03 5 .07 1.15 99.52 Sample Analyses, % By Weight * 3 4 5 6 7 56.11 0.07 0.13 0.08 0.05 0.22 29.40 7.50 0.18 0.10 0.03 5.00 1.03 99.90 56.14 0.03 0.13 0.11 0.03 0.15 29.56 7.40 0.25 0.10 0.03 5.56 0.96 100.45 52.81 0.08 0.16 0.08' 0.03 0.12 30.20 8.15 0.38 0.10 0.03 6.07 1.30 99.51 52.47 0.04 0.11 0.06 0.01 0.10 30.56 8.30 0.16 0.10 0.03 6.67 0.98 99.59 55.47 0.07 0.13 0.11 0.03 0.12 29.10 8.25 0.18 0.13 0.03 5.24 0.84 99.59 Talc Stds ** 61.49 0.01 1.20 0.38 1.07 0.00 30.54 0.46 -- -5.00 5.00 * Samples submitted to NIOSH by Company Analyses p e r f o r m e d by Dr. D.R. Bowes, University of Glasgow. * * From talc s t an d ar d a n a l y s e s in r ef e r e n c e 1. Table 4 Summary of TWA Exposures By Job, Mining Operations Job Title Fibers fibers >5 urn in length/cc (Optical Microscopy) Resp.Mass. Impinger ng/m3 mppcf i Free Si02 mg/m3 Crusher Operator Trammer Scrapper Man Underground Laborer Driller Mucker Cageman Repairman Repairman's Helper Blacksmith Maintenance Mechanic 9.8 ( 4) 5.6 (25) -- -3.0 ( 5) -9.5 ( 5) --- 2.6 ( 3) 1.7 (12) -- 0.64 (3) 1.29 (3) 0.58 (1) 0.98 (3) -- 0.23 (1) 1.14 (1) 0.86 (1) -0.42 (1) 10.1 (3) 11.8 (5) -0.7 (1) 15.8 (1 ) 2.0 (1) -3.6 (1) -1.5 (1) .. -- 1 0.020 (3) 0.012 (3) ! 0.006 (2) 0.014 (2) -- -- -- 0.000 -- 0.000 ( 1 ) s (1) 'i ( ) = Number of samples used for calculation of TWA values for each job category. Samples for respirable mass and free Si02 were full shift samples. -- indicates no samples 38 Table 5 Summary of TWA Exposures By Job Title job Title Mill Foreman General Laborer Crusher Operator Hardinge Operator Wheeler Operator Packer . Packer Serviceman Packhouse Foreman Fork Lift Operator Car Liner Bulk Car Loader Millwright Instrument Repairman Machinist Millwright Helper Sheet Metal Worker Oiler l Welder Fibers fibers >5 ym in length/cc (Optical Microscopy) 5.3 (9) 5.6 (5) 5 .1 (16) 7.9 (14) 8.4 (14) 5 .1 (48) 3.6 (11) 1.5 (5) 4.0 (15) 3.4 (4) 2.0 (3) 1.9 (3) 2.8 (6) 1.8 (3) 4.0 (2) 1.7 (3) 4.0 (4) 1.9 (3) Resp. Mass mg/m^ 0.58 (2) 1.14 (1) 0.85 (2) 1.09 (2) 1.56 (2) 0.59 (9) 0.42 (2) 0.25 (2) 0.35 (3) 0.31 (1) 0.25 (1) 2.37 (2) 0.59 (2) 0.40 (1) 2.96 (1) 0.50 (1) 0.72 (1) 0.75 (1) Impinger Free Si02 mppcf mg/m3 2.9 (2) 0.5 (1) 2.6 (4) 3.4 (2) 3 .1 (2) 3.6 (6) 2 .1 (D -1.6 (1) --- ---- --- - 0.013 (2) 0.014 (D 0.020 (2) 0.012 (1) 0.012 (1) 0.010 (7) 0.007 (2) 0.014 (2) 0.000 (1) 0.000 (1) 0.016 (1) 0.040 (2) 0.000 (1) 0.016 (1) 0.000 (D 0.013 (1 ) 0.016 (1) ( ) = Number of samples used for calculation of TWA values for each job category. Samples for respirable mass and free Si02 were full shift samples. 39 Table 6 Summary of TWA Amphibole Fiber Exposures (All Fiber Lengths) in Mining and Milling Operations As Determined by Analytical Electron Microscopy Job Title Mine Trammer Driller Cageman Mechanic Asbestos Fiber Cone, fibers/cc* 17.5 (4) 9.5 (1) 17.5 (1) 16.7 (1) Mill Mill Foreman 25.0 (2) General Laborer 23.6 (2) Crusher Operator Hardinge Operator 12.0 (2) 70.6 (2) Wheeler Operator Packer 22.9 (2) 36.0 (2) Packer Serviceman Packhouse Foreman 11.1 (2) 14.6 (2) Fork Lift Operator Machinist Welder 36.0 (1) 24.9 (1) 9.9 (1) ^Concentrations shown are only for those giving identifiable electron diffraction patterns and include tremolite and anthophyllite. ( ) Number of samples analyzed by electron microscopy. 40 Table 7 Summary of Airborne Fiber Types Determined By Analytical Electron Microscopy Operation All Fibers Mine Mill Percent of Airborne Fibers (All Lengths) Positive Amphiboles ** Tremolite ** An th oph y l l it e * 7' Positive Chrysotile NonAsbestos Not Identi fied*** 19 38 12 45 3 1 39 2 2 38 Fibers > 5 pm in Length (Mine & 7 65 Mill) , 0 3 25 * Airborne fibers were identified as positive amphiboles by selected area electron diffraction. ** Amphiboles di fferentiated by energy dispersive mi cr ochemical analysis. *** Electron diffraction patterns are not suffficient for identification; however, many had X-ray spectra identical to tremolite. Table 8 Summary of Airborne Fiber Diameters for Positive Amphiboles Operation and Fiber Type Mine * Tremolite (N=83) Anthophyllite (N=164) Mill Tremolite (N=160) Anthophyllite (N=687) ^Median Diameter Um 0.19 0.13 0.19 0.13 Geo. Std. Deviation 95% Conf. Interval For Median Diameter pm 2 .3 2.4 0.16-0.23 0 .12-0 .15 2.4 0.17-0.22 2.9 0 .12-0 .14 % < 0.5 ym 8 in Diameter 1 88 ] 93 J 87 1 9 0 I * Results of all samples combined for distribution analysis. N = Number of individual fibers identified and sized using electron m i c r o scopy . Table 9 Summary of Airborne Fiber Lengths for Positive Amphiboles Operation and Fiber Type ----------- j!----------------- Median Diameter pm Geo. Std. Deviation 95% C o n f . Interval For Median Diameter pm Mine * Tremolite (N=83) 1.6 Anthophyllite (N=164) 1.5 1 .8 2.6 1 .4- 1 .8 1.3-1.7 % <0.5 pm in Length 97 90-92 Mill* Tremolite (N=160) 1.5 1.9 1.4-1 .7 97 | Anthophyllite (N=687) 1.4 2.9 . 1 .3- 1 .5 90 * Results of all samples combined for distribution analysis. N = Number of individual fibers identified and sized by electron m i c r o scopy . 42 T a b le 10 Aspect Ratios for Positive Amphiboles Determined by Electron Microscopy (All Fiber Lengths) o CM V | Aspect Ratio Measurement Median Aspect Ratio Aspect Ratio _< 5/1 < 10/1 < 50/1 Tremo lite * Mine 'Mill 7.5 7.5 23% 24% 70% 70% 96% 96% >99% 99% Anthophy H i t e * Mine Mill 9.5 9.5 17% 15% 52% 52% 85% 88% 99% >99% * Data shown are for all fiber lengths. 43 Table 11 Job or Operation Summary of Historic Xmpinger Dust Measurements in Mine and Mill Operations 1954 1958 Mean Dust Concentration (mppcf) 1963 1964 1969 (1) 1970 (2) 1972 (2) 1973 (2) 1975 NIOSH 1975 Median Y e arly Average Mine Drilling 5 5 13 7 4 5 3 1 2 5 Dragline & Mucking 7 10 8 3 5 12 8 Tramming & Mucking 29 1 1 1 0 3 5 10-15 1 0 Primary Crushing 2 26 23 18 1 3 48 1 1 5 18 18 Hoist Loading 70 140 14 18 1 0 1 5 2 1 4 Mill Secondary Crushing 12 23 8 1 0 12 1 3 3 8 3 3 ' 9 Wheeler Grinding Hardinge Grinding Bagging Palletizing Bulk Loading Loading Bags 1 5 13 18 14 25 15 40 5 3 4 7 5 9 25 109 39 3 1 1 1 19 8 4 8 10 6 1 0 62 4 1 0 3 1 0 1 0 3 8 8 9 4 8 8 1 5 2 -1 0 35 5 0 Other Millwright Maintenance (1) Values for 1954 - 1970' taken from reference 16. (2) Calculated from MESA reports, references 33-42. 4 4 1 2 2 T a b l e 12 Summary of Historic Fiber Exposure Measurements in Mine and Mill Operations Job or Operation Mean ( 1 ) 1970 Fiber (2) 1972 Concentration (fiber > 5ym/cc (2) 1973 (2) 1974 (2) 1975 NIOSH 1975 (2) 1976 Mine Drilling 8 4 1 1 1 Dragline & M u c k i n g 16 6 1 2 Tramming & M u c k i n g 22 6 1 3 Primary Crushing 260 22 5 9 20 Hoist Loading 29 5 1 0 1 3 3 3 24 6 6 8 1 0 25 1 0 1 2 Mill Secondary Crushing 13 Wheeler Grinding 30 Hardinge Grinding 33 Bagging 30 Palletizing 27 Bulk Loading 8 Loading Bags 5 1 4 6 9 14 13 17 13 1 0 1 1 1 5 6 8 15 5 18 8 1 4 8 1 4 5 14 4 2 3 Other Millwright Maintenance 9 2 1 4 2-4 38 (1) Taken from r e f e r e n c e 16 (2) C a l cu la t e d f r o m M E S A reports, r e f e re n c e s 33-43 Table 13 Comparison of Airborne Fiber Characteristics in Study of Mine and Mill Operations with New York Talc Operations Acknowledged as Containing Asbestiform Minerals Airborne Fiber Characteristic Proportion Positive Amphiboles Proportion Anthophyllite Proportion Tremolite Median Fiber Length Anthophy H i t e Tremolite Median Fiber Diameter Anthophyllite Tremolite Median Fiber Aspect Anthophyllite Tremolite Ratio % of Fiber <5 ym in length Anthophyllite Tremolite Asbestiform Mine and Mill 0.50 0.47 0.03 1.61 ym * 0.16 ym * 9.9 * 92 * Study Mine and Mill 0.58 0.45 0.13 1.45 ym 1.55 ym 0.13 ym 0.19 ym 9.5 7.5 90-92 97 Statistical Significance p < 0.05 NS p < 0.001 NS -- NS -- NS -- NS * Insufficient number of fibers observed for calculation of size distribution parameters. NS - Not significantly different at 0.05 level. 46 TABLE 14 Summary of morbidity studies of workers exposed to tremolite and/or a n t h o p h y H i t e fibers Reference Mineral Characteristics Sample Exposure Medical Findings 20 Talc containing 45% tremolite 57 talc miners & Miners=4 mppcf Bronchi tis = 5 % and no free silica millers, 93% sample Millers=52 mppcf Dyspnea= 0% St. Lawrence CO., New York of one mine & mill Normal X-ray = 5% Fibrosis=67% Early pneumoconiosis = 26% Pneumoconiosis 11=2% CN 47 Steatite talc (70% talc, 10% tremolite, no quartz) Murray County, Georgia 66 talc miners & millers, 30 work ing at time of survey. 8/11 fe males working 33 millers=300 mppcf 13 miners=135 mppcf 20 workers=17 mppcf Pneumoconiosis (Grade) 0 1 2 3 High Exposure 52% 24% 15% 9% Medium Exposure 54% 46% - - Low Exposure 100% - - - 44 Fibrous talc containing tremolite, anthophyllite , 1% free silica St. Lawrence County, N.Y. 221 men at 3 talc mines and 5 talc mills . M i l l :crushing milling=46-61 mppcf M i n e :drilling= 1350 mppcf Stoping=1290 mppc f Mucking=35 mppcf Fibrosis Total population= 14.5% 10 years exposure= 29.9% 30 years exposure1 74 .% Visceral plaques=6.3% for those 35-75 years old, 4-52 years exposure. au TABLE 14 (c o n t i n u e d ) Reference Mineral Characteristics Sample Exposure Medical Findings 4 1 ID Talc admixed with tremolite and ant h o p h y H i t e and a small amount of free silic'a. Case histories of six talc miners and millers with pneumoconiosis. 24 years (20-23) talc exposure. Exposure in early years estimated as150"470 m p p c f ; in later years as 0-5 3 mppcf . Major Findings Clinical: Chronic productive cough, dyspnea, diminished breath sounds, limited chest expansion, diffuse rales, clubbing. X ray: Interstitial infiltration, opaque plate-like densities in region of diaphram; less frequent emphysema and obser vation of left car diac border. 8 Fibrous talc, St. Lawrence 30 talc mill- Mean duration Dyspnea = 5 3 .3% . Ab County, New York ers >10 years of exposure= normal findings exposure and no 19.5 years (rales, rhonchi, previous occupa - (13-26). Aver wheezing =26 .7%. tional dust ex age exposure= Pulmonary infiltra posure; 59% 63.1 m p p c f , 15 tion (X- ray )=43.3 % smoked >20 cig exposed 20-60 (4 is grade 1; 7 arettes per day mppcf grade 2; 2 grade 3) . for >J5 years 15 exposed 6 0 100 mppcf Mean % predicted FVC= 76.6%, Mean F V C % = .71% Mean % predicted RV/TLC=120.8; Mean % predicted R V = 105.2; Mean % predicted TLV=8 2 .1; Mean DLC0 = 23.7 _____________________________________________________________ _________________ __________ cc/mm Hg/min . TABLE 14 (continued) Reference Mineral Characteristics 9 Predominantly talc admixed with tremolite, anthophyl- lite , serpentine and <5% free silica. cn o Sample Exposure Medical Findings 16 Talc millers with >10 years talc exposure and no previous occu pational dust e xpos u r e . 8 1% smoked >30 cigarettes/day > 5 years. 7 avg exp= 20-60 mppcf Cough=44%. Exertional dyspnea=88%. Dyspnea at rest = 6%. Lung find- 2 avg exp> 12 0 mppcf bing=38%. Pulmonary Infiltration (x-ray) Grade 1 = 25% Grade 2 = 63% Grade 3 = 12% No platelike densities. % predicted FVC = 72.5% (48-9 1) 44 % were <75%- FEV % 7 0% (53-84) 6 % were <60%.___________ % predicted RV = 100% (72-153) 6 % were >13 3%._________ % predicted TLV = 81 % (54- 103) 3 1% were <73%.___________ % predicted R V / T L C = 12 1 .3 % (96-143) -5-0-%--w-e-r-e--->-1-2-4-%--.--------- - DLC0 19.2 cc/mm Hg/min (10-38) 38 % were <17.7%. R eference M in e ra l C h a r a c te r is tic s Sam p1 e Exposure M e d ic a l F in d in g s 1 0 ui 47 Talc admixed with tremolite anthophyllite, serpentine, and <5% free silica. Anthophyllite asbestos, Finland 43 talc millers with >10 years exposure and no previous occu pational dust e x p o s u r e ; 26 had s m o k e d >30 cigarettes/day for >5 y e a r s . 2% avg exp=19 mppc f 49% avg exp= 20-60 mppcf 42% avg exp= 60-120 mppcf 7% avg exp= >120 mppcf Cough = 33%. Dyspnea = 65%. Lung Crepitations = 28% . Cl ubbing = 19%. Pulmonary Infiltration (x-ray) Grade 1 = 9% Grade 2 = 23% Gr ade 3 = 5% % predicted FVC = 80% (30% <75% of p r e d . ) FEV% = 70% (12% had < .60 ) % predicted RV = 101% (14% >133%) % predicted TLC = 84% (16% <73%) % predicted RV/TLC = 1 16 % (37% >124%) Q O to DL .2 cc /mm Hg/min (19% <17.7) 707 living asbestos w o r k e r s (ineluding office & forestry workers with no occupa tional exposure); 110 of these 787 had been engaged in asbestos work for m o r e than 10 years. Nonsmoker < 15 c i g s / d a y >15 cigs/day Total Adjusted for Smoking Cough (%) Mod . All Exp . Hvy Exp 17% 14% 59% 32% 27% 57% 35% 30% 57% 2 7% 23% 58% Dyspne a (%) 20% 2 3% 1 3% 20% TABLE 14 (continued) Reference Mineral Characteristics 64 Anthophyllite, asbestos Finland Sample 252 living workers who had worked be tween 1936-1967. Exposure Medical Findings Respiratory disease = 44% Normal chest X-ray = 44% Changes in lung parenchyma (X-ray) = 39% Pleural pathology only (X-ray) = 17% Pulmonary and/or pleural pathology =58% Lung pathology excluding pleural lesions (X-ray) = Slight (7%); Moderate (15%); Severe (6%) 75 ww 1 1 Anthophyllite asbestos, Finland Talc with tremolite & anthophyllite as major fibrous components. 116 employed (103 men) & 24 retired (18 men) miners & millers . 39 talc workers exposed >10 years 49% has smoked >20 cigarettes/ day for >5 y e a r s . TLV for asbestos fibers/cc, > 5ym in length: 33%= 2 yrs exp. 27%= 5-15 yrs e x p . 30%=15-25 yrs exp. 7%= 25 yrs e x p . Asbestosis (X-ray) = 27% Mild (49%); Moderate (32%); Marked (19%) A v g . y r s . exp . 16.2 (11- 22) + Mine : Drilling 6 Mucking 20 Mill : Crushing 15 Mi 1 ling 1 3 Bagging 16 ++ 8 22 1 3 3 1.5 30 Cough = 26%; Dyspnea =23% Grade 1 = 67%; Grade 2 = 11%; Grade 4 = 22%; Lung Crepitations = 5%; Clubbing = 0% . Radiographic findings compatible with pneumoconiosi s = 3%. Reference Mineral Characteristics 1 1 T A B L E 14 ( c o n t i n u e d ) Sample Exposure + mean dust counts (mppcf) ov e r 20 year period ++ fiber count 75 ym/ml in 1970 only Medical Findings U1 >> 31 caMiiillMkitMNIHMItlKfiHiiMIHMMHlittHlCHWMMMMl T a b l e 15 A ge-S m oking C o m p o s itio n o f M o r b id it y S tudy P o p u la t io n No P r e v io u s O c c u p a t io n a l E x p o s u r e t o T a lc Who Had Smoking Status Nonsmoker Ex-smoker Smoker 20 -29 30 -39 n (%) n (%) 12 (41 ) 2 (11) 3 (10) 3 (17) 14.. (48) 13 (72) Age 40 -49 50 -59 n (%) n (%) 3 (11) 2 (12) 13 (48) 8 (47) 1 1 (41) 7 (41) 60 + n (%) 0 ( 0) 1 (50) 1 (50) Total n (%) 19 (20) 28 (30) 46 (49) Total 29 (31) ' 18 (19) 27 (29) 17 (18) 2 ( 2) 93 Cells are column percentages; marginals are percentages of the total. 55 T a b le 15A A ge-S m oking C o m p o s itio n o f T o t a l M o r b id it y S tu dy P o p u la t io n R e g a r d le s s o f P r e v io u s Em ploym ent 1------------------- 20-29 30-39 Age 40-49 50-59 60 + .T o t a l Smoking Status n (%) n (%) n (%) n (%) n (%) n (%) Nonsmoker Ex-smoker Smoker 16 (46) 3 ( 9) 16 (46) 3 (13) 3 (13) 18 (75) 4 (11) 16 (46) 15 (43) 3 (13) 13 (54) 8 (33) 0(0). 2 (67) 1 (33) 26 (21) 37 (31) 58 (48) Total 35 (29) 24 (20) 35 (29) 24 (20) 3 ( 2) 121 Cells are column percentages; ma rginals are percentages of the total. 56 Table 16 Age-Exposure Composition of Morbidity Study Population Who Had No Previous Occupational Exposure to Talc 2 0-29 Expos ure n = 2 9 Employment (years) Particulate Exposure (mg-years/m^) Fiber Exposure (fiber-years/cc) 2.7 (0.3) 2.0 (0.3) 10.4 (1.6) Standard Error in Parentheses 30-39 n=18 5.9 (0.8) 4.6 (1.0) 16.7 (3.3) Age 40-49 n=27 13.9 (1.4) 8.6 (1.3) 52.7 (7.6) 50-59 n= 17 19.5 (2.0) 11.3 (2.0) 68.8 (13.1) 60 + n=2 28.0 (0) 13.7 (11.7) 47.4 (41.4) Table 16A Age-Exposure Composition of Total Morbidity Study Population Regardless of Previous Employment 20-29 Exposure n= 3 5 Employment (years) Particulate Exposure (mg-ye ars / m3 ) Fiber Exposure (fi b e r - y e a r s / c c ) 3.0 (0.3) 2.3 (0.3) 12.5 (1.6) Standard Error in Parentheses 30-39 n = 2 4 5.8 (0.7) 4. 3 (0.8) 18.3 (2.8) Age 40-49 n= 35 14.0 (1.2) 9.3 (1.3) 55.7 (7.7) 50-59 n= 24 19.5 (1.8) 12.1 (1.7) 72.2 (11.2) 60 + n= 3 28.3 (0.3) 18.0 (8.0) 47.2 (23.9) T a b l e 17 and Radiographic Findings by Smoking Habits Among P r e v a l e n c e (%) o f S y m p to m s W h o H a d No P r e v i o u s O c c u p a t i o n a l E x p o s u r e to Tal Morbidity Study Population Symptoms/ Radiographic Findings Cough phlegm Hemoptysis D y s p n e a ( > G r a d e 2) Nonsmoker n = 19 o 10 5 0 0 Ex-smoker n =. 28 2 1.4 14.3 3.6 14.3 Smoker n = 46 52.2 5 0.0 13.0 19.6 Total n = 93 32 .3 p Value ---------- ' 0.0001 3 1.2 0.0005 7 .5 0.12 14.0 0.12 pleural Thickening ( > G r a d e 1) Pleural Calcification Irregular Opacities 10.5 5.3 u 14.3 0 0 8.7 10.8 0 1 .1 2 .2 1 .1 i-- 0.76 0.14 0.60 difference in rates among the three smoking categories H 0 : There is no T a b l e 17A i /i of svmoto ms and R a d i o g r a p h i c F i n d i n gs By S m o k i n g Habits Among H i * b i 4^ s " d, population Regardless of Previous Emp l o y,,e,,t Symptoms/ Radiographic Findings Cough Phlegm Hemoptysis D y s p n e a (>_Grade 2 ) p leural Thickening ( >Grade 1) pleural Calcification Irregular Opacities ( > G r a d e 1) Nonsmoker n = 26 J -2 19.2 0 7.7 7.7 3.9 0 Ex-smoker n = 37 24.3 16.2 8. 1 18.9 18.9 2 .7 8.1 Smoker n = 58 53.5 5 1.7 13.8 19.0 8.6 0 1 .7 Total.. n = 121 33.9 33.9 9. 1 16.5 11.6 1. 7 3. 3 p Value . 000 1 . 0004 . 12 .40 .24 . 37 . 13 Hq : T h ere i s no c l i f f s t o n e s i n r a t e s among t h e t h r e e sm oking c a t e g o r i e s . T a b l e 18 Pr ev ale nc e (%) of Sym p to m s and R a d i o g r a p h i c F i n d i n g s by Age Among M o r b i d i t y Study Population Who Had No Previous Occupational Exposure to Talc Symptoms/ Radiographic Findings . 20-29 n = 29 30-39 n = 18 40-49 n = 27 Age 50-59 n = 17 60 + n = 2 n = 93 P Value Cough O' o Phlegm 17.2 20.7 55.6 44.4 2 2.2 29.6 4 1.2 29.4 100.0 100.0 32.3 3 1.2 0.009 0.11 Hemoptysis 6.9 11.1 11.1 0 0 7.5 0.66 D y s p n e a (>^ G r a d e 2) 10.3 16.7 11.1 17.7 50.0 14.0 0.56 Pleural Thickening (>^ G r a d e 1 ) 0 0 7.4 4 1.2 50.0 10.8 0.0001 Pleural Calcification 0 0 0 5.9 0 1 .1 0 .34 Irregular Opacities (> G r a d e 1) 0 0 0 5.9 0 1 .1 0 .34 among the five age groups. H o There is no d i f f e r e n c e in rates Table 18A P r e v a l e n c e (%) of Symptoms and R a d i o g r a p h i c Findings by Age Am on g the Total Morbidity Study Population Regardless of Previous Employment Symptoms/ Radiographic Findings Cough P h 1egm Hemoptysis D y s p n e a (> G r a d e 2) Pleural Thickening (j> G r a d e 1 ) Pleural Calcification Irregular Opacities (>_ G r a d e 1 ) 20-29 n = 35 17.1 22.9 5.7 11.4 0 30-39 n = 24 58.3 50.0 12.5 16.7 0 40-49 n = 35 Age 50-59 n = 24 25.7 37.5 37 . 1 25.0 11.4 4.2 11.4 29.2 5 .7 4 1.7 60 + n = 3 100.0 66.7 33.3 33.3 66.7 Total n = 12 1 P Value 33.9 .00 1 33.9 . 1 3 9.1 .42 16.5 . 32 11.6 .000 1 0 0 0 8.3 0 0 2.9 12.5 0 1 .7 . 08 0 3 .3 .08 H 0 : There is no di ffe r e n c e in rates a mo ng the 5 age groups T a b l e 19 Prevalence (%) of Symptoms and Radiographic Findings Among Talc Workers '4 Included in Morbidity Study With No Preyious Occupational Exposure to Talc Compared to Coal and Potash Workers Adjusted for Age, Height and Smoking Habi Symptoms/Radiographic Findings Cough Phlegm Hemoptysis Dyspnea Pleural Thickening (Grade 1 and 2) Pleural Calcification** Irregular Opacities (Grade >1) Regular Opacities (Grade >_1) Years Worked Talc Coal Potash < 15 years > 15 years < 15 years > 15 years < 15 years > 15 years < 15 years > 15 years < 15 years > 15 years < 15 y e a r s * * > 15 years * * < 15 years** > 15 years < 15 years** > 15 years 3 1.3 34.5 34.4 24. 1 10.9 0 .0 12.5 17.2 1.6 3 1.0 0 .0 3.4 0 .0 3.4 0 .0 3.4 20.9 36.7 26.0 44.6 6.4 9.4 13.3 37.9 0.3 1 .6* 0 .0 0 . 1 0 .5 5.3 1 .0 13.7 23.2 25.6 27.2 23.7 6.4 6.7 5.3 11.3 0 .5 4.4* 0 .0 0 .0 0 .0 0 .7 0 .0 1 . 1 * p = < 0.05 Hypothesis being tested is that there is no difference in rates between the coal and talc populations, or between the potash and talc populations. ** Expected values not large enough for chi square test 62 Table 19A Prevalence (%) of Symptoms and Radiographic Findings Among All Talc Workers Included in Morbidity Study Compared with Coal and Potash Workers Adjusted for A g e , Height, and Smoking Habits Symptoms/Radiographic Findings Years Worked Talc Coal Potash Cough Phlegm Hemoptysis Dyspnea Pleural Thickening (Grade 1 and 2) Pleural Calcification irregular Opacities (Grade >1) Regular Opacities (Grade >_1 ) <15 32.9 >15 35.9 <15 37.8 >15 25.6 <15 > 15 11.0 5.1 <15 >15 <15 >_15 <15+ + >15+ + < 15++ >1 5 13.4 23.1 1 .2 33.3 0 5 .1 0 10.3 <15+ + >15 -------- --------- 0 2.6 2 1 .1** 37.5 23.3 26.7 26.0** 45.7** 27.4 23.7 6 .5 6.2 10.4 6.4 13.7 39.2* 5.3 13.4 0 .3 0 .5 1 _5 * * * * 2 . 1 **** 0 0 .1 0.6 5.6 0 0 0 0.4**** 1 .0 0 14.5 1 .6 LoO V I! *P * * P = < . 02 ** * P = <.005 * ** * P = <.0005 HQ : There is no difference in rates between the coal and talc populations , or between the potash and talc popula tions. + N= 37 for potash comparisons. ++ Expected values not large enough for chi square test. 63 Table 20 Dose-Response Relations Among Talc Workers Observed Pulmonary Function As Compared to Pulmonary Function of Coal and Potash Miners, Adjusted For Age, Height, Smoking Habits and Years Worked. (Standrard Error in Parenthesis) A Mean Percent Predicted and Pulmonary Function of Talc Workers Compared to Coal and Potash Workers FEV FVC a . n = 93 b. n - 12 1 a . n = 93 b. n = 1 2 1 Coal * * * * 94.0 (1.3) * * ** 93.8 (1.3) * * ** 92.4 (1 .2 ) * * * * 9 1.9 (1 . 1 ) Potash ****94.5 (1 .4) * * * * 9 4 . 1 (1.3) ****9 4 . 7 ****9 4 . 0 (1.3) (1 .2 ) FEV% a . n = 93 b. n = 12 1 Peak Flow c . n = 89 d. n = 1 14 1 0 1.3 (0.7) 101.5 (0.7) ** 108.1 (2 .8 ) ** * 108.5 (2.5) 99.8 (0.7) 99.9 (0.7) 99.4 (2 .6 ) 99.5 (2.3) FEF2 5 c . n = 89 d. n 1 14 93. 6 94.0 (2 .8 ) (2.7) * * ** 8 8 . 8 (2.7) ****88.9 (2 .6 ) f e f 50 c . n = 89 d . n -- 1 14 ** * * 85.9 (3.1) * * * * 8 6 . 8 (2.9) ****85.3 (3.2) ****85.6 (2.9) FEF 7 5 c . n = 89 d. n = 114 * ** * 79.5 (3.1) * * * 79.9 (2.9) ****83.7 (3.3) ****83.6 (3.0) Hq : Mean predicted pulmonary is not different from 1 0 0 . + Percent pred ict ed for FEV F V C , Peak Flow, FEF5q > fef75 ~ 100 x observed predicted For FEV% = 100 + observed-predicted. 64 Ta ble 20 (continued) B 1. B2 . p e r 100 f i b e r - y e a r s / c c Change in p e rc e n t p r e d ic te d pulm onary fu n c tio n FEV 1 FVC FEV% a . n = 93 b. n - 121 n il a. 93 b. 1 2 1 a . n = 93 b . n = 121 Coal ** it -k * - 9.4 10.3 (3 . 2) (3 . 0) ** - 9.6 (3.1) **** - 11.6 (2.6) + 0.2 (1. 7) + 0.8 (1.5) potash **** _ 13.7 **** _ 14.4 (3 . 4 ) (3 . 1) *** - 12. 7 (3 . 3 ) **** _ 1 4 . 7 (2 . 8 ) - 0.7 (1 . 8 ) - 0 . 0 5 (1 .6 ) p e a k F l o w c . n = 89 d . n= 114 + 2.7 (7 . 1) + 0.4 (5 . 7 ) -- 2 . 3 (6 . 5 ) 4.0 (5 . 2) f e f 25 c . n = 89 d . n = 114 + 4.8 (6.9) + 3.0 (6.2) _ 0 . 3 (6.8) - 1 .5 (5 . 9 ) f e f 50 c . n = 89 d . n = 114 -2.5 - 5.0 (7 . 7 ) (6 . 7 ) 7.6 (7 . 9 ) 9.7 (6.6) FEF75 c . n = 89 d . n = 114 - 9.7 -12.0 (7 .7 ) (6.6) 13.8 * -- 1 5 . 9 (8 . 3) (6 . 9 ) C h a n g e i n p e r c e n t p r e d i c t e d p u l m o n a r y f u n c t i o n 3r 10 m g - p a r t i c u l a yrs/m g3 FEV1 FEV a . n = 93 b . n = 12 1 a . n = 93 b . n = 121 fev% a . n = 93 b . n = 121 p e a k . F l o w c . n = 89 d . n = 114 FEF25 c . n = 89 d . n = 114 f e f 50 c . n = 89 d. n = 114 FEF 75 c . n = 89 d . n = 114 * 5.2 ( 1 . 9 ) * 3.8 (1.8) * * * * * 5 . 3 5.5 (1 . 9 ) (1 . 6 ) + 0.2 + 1.2 (1.0) (0 .9) + 1.2 + 1.6 (4 . 2 ) (3 . 3) + 2.2 - 1.4 + 1.2 (4 . 1) (3 . 6 ) (4 . 6 ) (4 . 0) - 4.6 - 1.8 (4 . 6 ) (3. 9) *** it * - ** **** - 7 . 5 (2.2) 6.2 (1. 9) 6.7 (2.1) 7 . 1 (1.8) - 0.6 (1.1) + 0.6 (0 . 9 ) + 0 . 0 8 (4 . 0) - 0.2 (3 . 1) - 2.3 (4 . 2 ) - 0.4 (3 .6 ) - 4.8 (4 . 9 ) - 2.7 (4 . 0) - 7.9 (5 . 1) - 5.1 (4 . 2 ) -- _________________" ,, Change in pulm onary fu n c t io n i . n ot d i f f e r e n t from 0 . H, 65 * p = <_0 . 05 ** p = <_0 .005 *** p = <_0.001 **** p =<^0.0001 Table 20 (continued) a . For potash comparison, n =91 for FEV, F V C , FEV% b. For potash c o m p a r i s o n , n = 119 for FEV, FVC, FEV% c . For pot ash c o m p a r i s o n , n=87 for Peak Flow, F E F 2 5 F F F 50' F E F 7 5 . d. For p o t a s h c o m p a r i s o n , n=112 for P e ak Flow, F E F 2 5 > F E F 50 F E F 7 5 ' 66 able 2 1 Comparison Previous of Talc Workers Included in Morbidity Study and Having No Talc Exposure With and Without Pleural Thickening (PT)* By Age, Exposure, and Smoking Habits. (Standard Error in Parentheses) N=93 N Age Smoking (pack years) Years Worked Particulate Exposure (mg-yrs/m3 ) Fiber Exposure (fibers-yrs/cc) % Predicted FEV Coal . Potash % predicted FVC Coal Potash No PT PT No PT PT No PT PT No PT PT NO PT PT No PT PT No PT PT No PT PT No PT PT No PT PT Age 40 -49 50 -59 25 2 44.4 46.5 27.8 39.0 13.8 14.5 8.7 7.9 52.5 55.9 ( 0.5) ( 0.5) ( 4.7) (23.0) ( 1 .4) ( 6.5) ( 1.4) ( 3.9) ( 7.9) (41.0) 1 0 7 53.1 5 1.9 39.0 18.6 16.5 23.7 11.3 11.2 59.5 82.0 ( 0 .6) ( 0 .6) ( 8 .6) ( 5.2) ( 3.1) ( 0.9) ( 2 .6) ( 3.4) (16.7) (41.0) 97.9 80.8 96.3 77.7 ( 2 .6) ( 3.2) ( 2 .8) ( 5.3) 90.6 77.6 89.4 75.4 ( 4.7) ( 5.3) ( 5.0) ( 5.4) 95.9 72.9 96.7 72.5 ( 2.4) ( 7.1) ( 2.5) ( 8.7) 8 6 .7 ( 4.5) 77.6 ( 4.4) 8 8 .3 ( 4.8) 77 .1 ( 4.3) 60 + 1 1 63.0 5 1.9 99.0 44.0 28.0 28.0 25.4 2.0 88.8 6.0 84.0 87.3 -8 6 .7 79.6 82.8 -83.2 * Pleural thickening (Grades 1 and 2). 67 T a b l e 2 1A Exposure Comparison of All Talc Workers in Morbidity Study With and Without Pleural Thickening (PT)* By Age and Smoking Habits. (Standard Error in Parentheses) N=121 Age 40 49 50 59 60+ N Age Smoking (packing years) Years Worked Particulate Exposure (mg-yrs/m3) Fiber Exposure (f i b e r - y r s / c c ) % Predicted FEV Coal Potash % Predicted FVC Coal Potash No PT PT No PT PT No PT PT No PT PT No PT PT No PT PT No PT PT No PT PT No PT PT No PT PT 33 2 44.5 46.5 26.8 39.0 14.0 14.5 9.4 7.9 55.6 55.9 95.5 80.8 94.2 77.7 94.5 72.9 95.6 72.5 ( 0.4) ( 0.5) ( 4.0) (23.0) ( 1 .3) ( 6.5) ( 1.3) ( 3.9) ( 8 .0) (41.0) ( 3.1) ( 3.2) ( 3.3) ( 5.3) ( 2 .6) ( 7.1) ( 2 .8) ( 8.7) 14 10 53.3 52.4 30.4 24.6 16.6 23.5 11.1 13.5 57.8 92.4 91.9 77.8 90.0 75.4 87.4 77.6 88.3 77.0 ( 0.5) ( 0.7) ( 7.2) ( 6 .8) ( 2 .6) ( 1.5) ( 2 .2) ( 2.7) (12.8) (18.9) ( 3.8) ( 5.8) ( 3.9) ( 6 .0) ( 3.4) ( 4.7) ( 3.6) ( 4.8) 1 2 63.0 (---- ) 60.5- ( 0.5) 99.0 (---- ) 27.0 (17.0) 28.0 28.5 25.4 14.3 88.0 26.4 84.0 102.9 (---- ) ( 0.5) (---- ) (12.4) (---- ) (20.4) (---- ) (15.6) -- 98.2 (11.5) 79.6 (---- ) 89.0 ( 6.2) -- 88.0 ( 4.8) * Pleural Thickening (Grades 1 and 2) 68 Table 22 Average Number of Years Worked for Each Individual in Morbidity Study Having No Previous Talc Exposure With and Without Pleural Thickening and the Number of These Individuals Working in Selected Jobs Over the Total Work History Of Those With Greater Than 15 Years Work When 0, 5 and 10 of the Most Recent Years Worked are Omitted. Selected Jobs Are Those Where the Number of Years Worked Divided by the Number With Pleural Thickening is Equal to or Greater Than One and Greater Than Average Years Worked for Those Without Pleural Thickening. Average Number of Years Worked/Individual All Years PT No PT (Number of Individuals Ever on this Job) Omit Most Recent Five Years PT No PT Omit Most Recent Ten Years PT No PT Mine Foreman Hoistman Crusher Operator Packer Packer Serviceman Quality Control Technician Shipping & Inventory Coord. All Other Jobs All Jobs 19 ( 1 ) 26 ( 1 ) 24 ( 1 ) 14 ( 2 ) 10 ( 2 ) 16 ( 1 ) 13 ( 2 ) 5 .1 (1 1 ) 1 0 .2 (2 1 ) 7.7 ( 3) 1 (D 8 ( 2) 14 ( 2 ) 0 4 ( 2) 0 8 .1 (43) 8 . 0 (53) 14.1 ( 1 ) 2 1 ( 1) 20 ( 1 ) 9 (2) 7.5 ( 2 ) 16 ( 1 ) 16 ( 1 ) 5 (1 0 ) 9 . 0 (19) 7 ( 2) 1 ( 1) 6 .5 ( 2 ) 12.5 ( 2 ) 0 1 .5 ( 2 ) 0 7 (38) 6 .9 (47) 9 ( 1) 16 ( 1 ) 2 ( 2) 1 ( 1) 15 ( 1 ) 4 ( 2) 11 ( 1) 5 (2) 8 .5 ( 2 ) 0 12 ( 1) 2 ( 1) 11 ( 1) 0 4 . 6 ( 9) 5.4 (35) 7.4 (17) 5.2 (43) Note: Numbers for "All Jobs" and All Other Jobs" will exceed number of individuals with (9) and with (2 0 ) pleural thickening, since many have held more than one job. Table 23 Symptom Prevalence, Radiographic Findings and Pulmonary Function By Pleural Thickening (PT) and Years Employment PT =0 <15 Years Employment PT = 0 >_15 Years Employment PT = 1** >15 Years Employment Age (Average) Symptom Prevalence (95% n = 81 32.9 (1 .1 ) n = 26 * * 48.9 (1.0) n = 8 50.9 (1.1) Confidence Levels in Parentheses) Cough Phlegm Hemoptysis Dyspnea ( > Grade 2) Pleural Calcification Irregular Opacities 32.1 (22-44) 37.0 (26-49) 9.9 (4.5-19) 13.6 ( 7-24) 0(0-5) 0(0-5) 34.6 23.1 0 19.2 0 3.9 (18-55) ( 9-43) ( 0-13) ( 7-39) ( 0-13) ( 0 -2 0 ) 12.5 12.5 12.5 25.0 25.0 25.0 ( 0-50) ( 0-50) ( 0-50) ( 3-65) ( 3-65) ( 3-65) Pulmonary Function (Standard Error in Parentheses) FEV 1 (% Pred) FVC (% Pred) FEV% Coal Potash Coal Potash 95.5 97.5 94.4 97.9 (1.3) (1.5) (1 .2 ) (1.3) 78 .1 (0.9) 95.0 91.5 9 1.4 90.4 (3.4) (3.5) (3.1) (3.1) 75.3 (1.3) 83.8 80.9 80.1 79.5 (3.2) (3.5) (3.6) (3.7) 76.0 (1.7) Peak Flow (% Pred) FEF2 5 (% pred) FEF5 0 (% Pred) FEF7 5 (% Pred) Coal Potash Coal Potash Coal Potash Coal Potash n = 74 106.1 99.5 (2 .8 ) (2.7) 91.6 88.6 86.6 87.3 (3.0) (2.9) (3.1) (3.3) 82.6 (3.2) 87.4 (3.5) 113.4 (5.5) 99.7 (4.5) 98.4 89.9 91.1 86.2 (6 .1 ) (5.9) (7.2) (7.0) 80.3 (7.0) 82.2 (7.5) 113.2 (10.7) 99.8 ( 9.9) 102.6 92.9 82.9 79.1 (1 0 .1 ) ( 9.6) (1 0 .0 ) (10.7) 65.3 ( 6.3) 65.4 ( 5.1) PT = 2 >15 Years Employment n = 6 55.2 (2.0) 83.3 (40-100) 66.7 (25-95) 33.3 ( 4-75) 33.3 ( 4-75) 0 ( 0-45) 16.7 ( 0-60) 79.1 76.5 76.4 75.8 (11.5) (1 1 .1 ) ( 7.4) ( 7.7) 70.2 ( 4.1) 1 1 0 . 6 (17.2) 97.2 (16.3) 93.4 83.5 76.0 70.9 (2 1 .1 ) (19.3) (24.5) (2 0 .0 ) 65.5 (22.3) 66.7 (19.9) * One individual has less than 15 years employment; all others with PT > 1 have more than 15 Years employment. ** n=24 for the potash comparisons. 70 Ta ble 24 Symptom Prevalence (%) of Talc Workers Compared to Asbestos1 and Synthetic Textile Workers2 By Age and Smoking Habits Nonsmoker Ex-smoker Smokers Total Winter Cough (3 mos /y..r_l Age s Asbestos Workers 2 1-35 19 27 36-69 35 2 1 Talc Workers 20-39 0 33 40-65 0 2 1 49 42 65 56 48 24.4 60 38.3 Anthophyllite Asbestos Workers-heavily exposed 16.8 -- greater than 1 0 years3 <15=32.0 >15 = 3 5 . 6 26.6 Phlegm in Winter (3 mos/ yr ) Ages Asbestos Workers 2 1-35 26 27 36-69 40 30 43 38 5 1 47 Synthetic Textile 15-39 ,6 0 Workers .40-7 0 9 5 Talc Workers 20-39 18 17 40-65 20 1 1 12 1 0 22 1 7 45 24 60 37 Breathlessness- Grade 2 or More Ages Asbestos Workers 2 1-25 0 0 36-39 22 23 1 3 9 23 23 Synthetic Textile 15-39 6 5 Workers 40-7C 4 7 6 6 9 / Talc Workers 20-39 6 17 14 9 40-6E 0 14 20 1 7 Anthophyllite Asbestos3 19.8 - - < 15 = 23.0 19.9 (dyspnea at -rest) >15=13.3 (1) From J.C. McDonald et. al.: Respiratory Symptoms in Chrysotile Asbestos Mine and Mill Workers of Quebec. Arch E n v . Health, 24:358, (1972). (2) J. A. Merchant: Epide mi ol og ic al Studies of Respiratory Disease Among Cotton Textile Workers, 1970-73. (Rates are calculated from white men working in synthetic wool mills in North Carolina, 1970-71 .) (3) L.O. Meurman, R. Kivilvoto, and M. H a k a m a : Mortality and M o r bidity Among the Working Population of Anthophyllite Asbestos Miners in Finland, Brit. J. Ind. Med., 31:105, 1974. 71 Hable 25 Prevale nce of Radiographic Findings in Talc Workers Compared to Asbestos W o r k e r s 1 Over 35 Years of Age and After Age Adjustment Prevalence (%) of Radiograph Lc Findings Pleural Thickening Pleural Calcification Irregular Opacities Talc Workers with no previous occupational exposure (n=5 2) Asbestos Workers1 Talc Workers regardless of previous employment (n=7 0) Asbestos Workers1 25.0 p< .0 1 4.8 28.6 4.9 A O 3.8 N .S . 2.9 7 .1 3.0 N. S . 1 .9 N .S . 5.6 5.7 N .S . 5.8 (1) Data from C.E. Rossiter e t . a l . , (1972). Radiographic Changes in Chrysotile Asbestos Mine and Mill Workers of Quebec, Arch. Env. Health 24:388 (ref. 76). This Study of asbestos workers used the 1968 ILO/UICC classifi cation for pneumoconiosis. There are no differences in the 1968 and 1976 classification for irregular opacities, pleural thickening and pleural calcification. 72 Table 26 Summary of the Prevalence of Pleural Thickening (PT) in Workers Exposed to Asbestos Reference 56 (1968) 62 (1969) w 63 (1972) 61 (1972) 76 (19 72) Exposure____________ Naval Dockyard; all types of asbesots fibers Former anthophyllite asbestos workers. n=4 10 Men & women >40 yrs attending chest clinic in Birmingham (UK) area. n= 386 8 1 0% sample of 3 naval dockyards. n=2442 2 Chrysotile Asbestos Mines and Mills Prevalence of PT Continuous Exposure n Extensive PT Limited Plagues of PT Prevalence (%) Of Diffuse PT All No Pulmonary Fibro sis Pulmonary Fibrosis 42 5% 24% 35 % 9% 26 % Intermittent Exposure 688 1 % 4% Varied or Insignifi cant ExpOsur e 684 < 1% 2% % of Cases with 15 Yrs. Since Expo sure 9 1% 88% Grade Diffuse PT Grade Grade Grade No pulmonary change s 1 pulmonary change s 2 pulmonary changes 3 pulmonary changes 1 71 % 50% 2 1% 1 1% 2 3 14% 14% 32% 1 8 % 58% 2 1 % 26% 63% 6 % had noncalcified pleural lesions. 1 % had pleural calcification, and ^,1 / 2 o.f these also had non calcified pleural lesions. __________^ Extensive noncalcified PT = 0.01% Limited noncalcified PT = 0.01% Pleural abnormalities were more frequent than parenchymal , disease. 36-40 n= 1449 PT >Grade 1 1.4% PT 7Grade in Production Wkrs. at : Thetford Mine 2 .8 % Asbestos 0.7% PT by Age 4 1-45 46-50 1446 1 066 2.7% 5.8% 5 1-55 8 6.7 7.2% 4.2% 1.7% 7.1% 4.1% 8 .0 % 3.6 % 56-60 656 7.8% 7.9% 4.6% 6 1-65 64 1 12.3% 11.5% 7.6% TOTAL 11207 3.8% 6 .4% 3.2% ^.^MIWStelS Table 26 Summary of the Prevalence of Pleural Thickening (PT) in Workers Exposed to Asbestos (c o n t i n u e d ) 36-40 41-45 46-50 51-55 56-60 61-65 TOTAL In Factory Workers: n = % in PT 8 7 1.1% 76 2.6% 66 4.5% 44 6 .8 % 61 64 4.9% --- 967 1.4% 77 (1975) -4 i> % PT by Dust Index <10 10-99 100-199 Production Workers: Thetford Mine Asbestos 2.4% 2.9% 4.6% 2.6% (dust Level x yrs worked) 200-399 400-799 800+ 5 .8 % 3.0% 8.3% 4.7% 10.5% 5.8% 2 asbestos cement manufacturing plants; primarily chrysotile but some exposure to crocidolite, amosite silica, talc, mica. Average age = 45 (21-79) Average dust exposure: 17 yrs (1 month-45 yr s .) n = 233 (%) 50 233 9% 50-100 92 1 5% % PT by mppcf-yr 100-200 200-400 400+ TOTAL 1 3 0 22% 245 16 % 1 59 16 % 859 1 5% m tm * Vital Status of Talc Workers Included in Mortality Study Who Began Employment Between 1947-1960 Known to be alive Known to be deceased Unknown vital status Total - 308 74 1 6 398 ---------------- ---- . ' Table 28 Study Cohort of Talc Workers Included in Mortality Study - According to Length of Employment Duration of Employment < 1 month 1 month - 6 months 6 months - 1 2 months 1 year - 1 0 years > 1 0 years Total Number 74 97 3 1 90 106 398 75 T a b l e 29 Study Cohort of Talc Workers Included in Mortality Study According to Date of Initial Employment Date of Initial Employment 1947 - 1949 1950 - 1954 1955 - 1959 Total Number 174 156 68 398 76 T a b l e 30 Observed and Expected Deaths According to Major Causes Among Talc Miners and Millers Included in Mortality Study Cause of Death Number Respiratory T.B. Malignant Neoplasms 001-008 140-205 Diseases of the Heart 400-443 All Non-malignant Respiratory Disease Accidents 470-527 E800-E999 Other Known Causes Total _____ ___________________ _-- * p < 0.05 Observed 3 .0 19.0 27.0 8 .0 10.0 7.0 74.0 Expected 0.49 10.6 26.5 2 .9 6 .4 14.4 6 1.3 SMR 6 10* 180* 102 280* 156 -- 120 77 Table 30A Observed and Expected Deaths According to Specific Cause Among Talc Miners and Millers Included in Mortality Study Cause of Death Malignant Neoplasms Digestive System Respiratory System Bronchogenic Lymphatic and Hematopoietic Other Neoplasms All Non-malignant Respiratory Disease Influenza, Pneumonia, Bronchi tis and Acute Upper Respira tory Infection Other Non-malignant Respiratory Diseases Number 140-205 150-159 160-164 162-163 200-205 470-527 470-502 510-527 Observed 19.0 3 .0 10.0 9.0 4.0 2.0 8.0 3.0 5.0 Expected 10.6 3.0 3.5 3.3 1 .2 2.9 2.9 1 .5 1 .3 '* p < 0.05 ** p < 0 . 0 1 SMR 180* 1 00 290** 270* 3 30 69 280* 200 380 * T a b l e 31 Br on cho ge nic Cancer Among Talc Miners and Millers Included in Mortali ty Study Accordi ng to Interval Since Onset of Employment (Latency) Interval Sitice Onset of Employment (years) < 10 10-19 20-28 Observed 0 3 6 Expected 0 .5 1 .5 1 .3 SMR -- 200 460** Total 9 3.3 270* ** p < 0.01 * p < 0.05 79 Table 32 Case Review of Deaths Among Talc Miners and Millers Included in Mortality Study According to Cause of Death and Select Demographic Factors Case D .0.B . Age at Death A p p . Length of Emplymt. (Date of Initial Emplymt.) Latency (Years) A. Cancer of Respiratory System 1 12/04/06 63 1 month (8/10/49) 2 1 2 05/22/17 54 1 month (10/2 1/48) 23 3 06/08/14 59 1 year (11/08/48) 25 4 03/19/24 46 2 months (11/22/48) 2 1 5 06/ 14/09 55 6 06/28/07 53 3 years (07/19/48) 18 5 years (08/04/54) 6 7 05/10/20 54 2 .5 years (07/12/50) 24 8 04/22/891 79 < 1 month (12/13/48) 22 9 01/03/22 39 2 .5 years (07/13/49) 1 2 1 0 10 /1 0 /1 1 62 17 years (0 1/2 5/56) 18 Other previous Emplymt. (Length of Emplymt.) Unknown Coal Supply (7 months) Diamond Drill Other N.Y. State Talc Co. Repairman-Other N.Y. Talc Co. (5 months) Shaftman-Lead Mine (14 m o n th s ) State Rock Quarries (2 years) Aluminum Plant (4 years) Iron Ore Mine (4 months) Road Building (5 years) Mining ( 6 years) Foundry (10 years) Other N.Y. State Talc Co. (5-6 years) Mucker-Mining (7 years) Construction (unknown length) Mucker-Lead Mine (" ") Unknown B. Mesothelioma of Lung 1 02/08/06 62 16 years (12/04/52) 16 Construction (11 years) T tiM mirthiitfsiiiMftirfr ifTiiiiiiim i M f r -11" 1 - * ii ni i 6 d-yf.%< iwa p y ,'VTniBA w w Y ir t- ti fa T a b l e 32 (cont inu ed) C . Mon-malignant Respiratory Disease Other Than Influenza and Pneumonia 1 08/07/885 75 2 01/07/16 59 3 09/08/13 58 4 03/07/26 49 5 06/20/10 58 1 0 year s < 1 month 14 year s (11/01/48) (12/15/48) (06/14/54) 1 0 year s (04/05/52) 1 year (04/17/50) 1 3 Unknown 27 Unknown 17 Mucker & Driller - L i m e s t o n e (9 years) 2 3 Other N.Y. State Talc Co. (5 years) 18 Unknown D. Re s pi rat or y T.B. 1 12/06/21 49 2 02/11/09 53 3 10/30/29 42 4 years (06/25/49) 5 months (07/11/49) 6 years (09/11/54) 2 1 C o n s t r u c t i o n (4 months) M i n e r - L e a d Miner (3 month: 12 Miner-Other N.Y. State Talc Co. (16 years) Miner-Lead Mine (unknown length) 17 Unknown F i g u r e 1. Typical Electron Diffraction Patterns and X-ray Spectra of Tremolite Fibers in Bulk Samples Magnification 10,000 X 1 Micron Magnification 1,700 X 10 Micron j-------h 82 F i g u r e 2. T y p ic a l S pectra E le c t r o n D if f r a c t io n P a tte r n s and X ray o f A n t h o p h y 11 i t e F i b e r s i n B u l k S a m p l e s X-rav Snectrum Diffraction Pattern Mag1n0i,f0i0c0atXion 1 Micron 4 Magnification 5,000 X 1 Micron ooo'e 00 Figure 3. E l c t r o n P h o t o m i c r o g r a p h of A i r b o r n e P a r t i c u la t es in Mine and Mill mm a ^ T A T tM MAGNIFICATION 3,000 X 1 MICRON - 10 MICRON -- --------- Figure 4 Electron Ph o t o m i c r o g r a p h of Airborne P a r t i c u l a t e s in Mine and Mill KljllV'J F i g u r e 5. E l e c t r o n P h o t o m i c r o g r a p h o f A i r b o r n e P a r t i c u l a t e s in M i n e a n d M i l l MEAN DUST CONCENTRATION (MPPCF) Figure 6 . Mean Yearly Impinger Dust Concentrations for Mine Operations All Oprations Drilling, Dragline, Loading, Tramming and Mucking 65 J____ I___ I-- YEAR OF MEASUREMENT I 70 I____ I____ L 34 30 26 22 < F i g u r e 7. Mean Yearly Impinger Dust Concentrations for Mill Operations < _ All Operations All Operations Except Bag Loading 18 14 10 / 6 V 2 19 55 1 i t i i_ I_ _ i- - 1- - - 1- - 1- - - L 60 65 70 75 YEAR OF MEASUREMENT REFERENCES 1. Rohl, A .N ., Langer, A.M., S e lik o ff, I . J . , K1im entidis, R., Bowes, D.R. and Skinner, D.L., 1976. Consumer Talcums and Powders: Mineral and Chemical C haracterization. J. T o x ica l. Environ. Health. 2:225-294. 2. Stemple, I.S. and Brindley, G.W., 1960. A Structural Study o f Talc and Talc-Trem olite R elations. J. Ceramic Soc. 43 No. 1:34-42, January. 3. 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J . , R in ta la , E. and W iik e ri, J . , I 1972. A nth ophyllite Mining and M illin g as Causeof I Asbestosis. In: B io lo g ica l E ffe cts o f Asbestos, fj Proceedings o f a Working Conference held at Lyon, France, ' October 2-6, p. 165. 76. R ossiter, C.E. et a l. , 1972. Radiographic Changes in C hrysotile Asbestos Mine and M ill Workers of Quebec, Arch. Env. Health 24:388. 77. W e ill, H., Ziskind, M.M., Wagenspack, D. and R ossiter, C.E., 1975. Lung Function Consequences o f Dust Exposure in ' Asbestos Cement Manufacturing P la n ts, Arch. Env. Health 30:88. 95 Appendix. Summary (Tables Statistics for HIOSH A - 1 through A-10). 1975 Industrial Hygiene Study Table A - 1 Summary of Fiber Exposures in Mine O p erations as Dete r m i n e d by Optical M i c r o s c o p y Operation or Job F i b e r >5 ym in L e n g t h p e r cc Range of Individual Samples M e a n (+_ S E ) of Individual Samples M e d i a n of Individual Samples TimeWe ighted Average C r u s h e r O p e r a t o r (4) T r a m m e r (25) Driller (5) C a g e m a n (5) B l a c k s m i t h (3) M e c h a n i c (12) 7.7 - 14.7 2.3 - 14.6 0.9 - 6.8 6.0 - 18.2 1.2 - 4.4 0.2 - 3.9 10.3 + 1.5 6.4 + 0.7 3.9 + 1.0 10.3 + 2.1 3.1 + 1.0 1.9 + 0.3 9.3 5 .1 4.6 8.4 3.7 1 .9 9.8 5.6 3.0 9.5 2.6 1 .7 ( ) Number of samples SE Standard error 97 TABLE A-2 Summary of Fiber Exposures in Mill O p e r a t i o n s as Determined by O p t i c a l Micros c o p y Operation or Job Mill Fo r e m a n (9) General Labore r (5) Crusher Operator (16) Hardinge Operator (14) Wheeler Operator (14) packer (48) 00 packer Serviceman (11) pack hou se Foreman (5) Fork Lift Operator (15) Rail Car Liner (3) Bulk Car Loader (3) M i ll wr i gh t (3) I n s t r u m e n t R e p a i r m a n (6 ) Ma ch in is t (3) Mi l lw r i g h t Helper (2) Sheet Metal Wor ker (3) Oiler (4) Weld er (3) ( ) Number of samples SE Standard error 1 I--1 rH Range of Individual Samples 2.4 - 16.0 1.5 - 13.2 1.7 - 11.6 1.7 - 26.8 2.6 - 29.1 0.2 - 21.0 1.6 - 8.3 1.0 - 1.9 8 .3 1.3 - 5.6 1.6 - 2.4 0.9 - 2.6 1.2 - 4.0 0.3 - 3.6 0.7 - 8.9 1.2 - 2.2 1.7 - 4.5 0.8 - 3.1 M e a n (+ SE) of Individual Sample s 5.8 + 1.4 5.8 + 2.0 5.5 + 0.9 8.7 + 1.8 9.9 + 2.1 6.9 + 0.6 4.9 + 0.7 1.5 + 0.2 4.5 + 0.5 3.8 + 1.0 1.9 + 0.2 1.9 + 0.5 2.8 + 0.4 1.5 + 1.1 4.8 + 4.1 1.8 + 0.3 3.6 + 0.7 1.8 + 0.7 Med i a n of Individua1 Samples 4.7 5.5 4.7 6.4 6.5 6.1 5.5 1.6 4.6 4.1 1.8 2 .3 3 .0 0.5 4.8 1.9 4.1 1.6 TimeWeighted Average 5 .3 5.6 5 .1 7 ,9 8 4 51 3.6 1.5 4.0 3.4 2.0 1.9 2.8 1.8 4.0 1.7 4.0 1.9 h; <; ' .V. ;-;, r - /- TABLE A-3 Summary of Amphibole Fiber Exposures xn M i n e Operations as Determined by Analytical Electron M i c r o s c o p y SE Standard error TABLE A-4 Summary of Amphibole Fiber Exposures in Mill Operations as Determined by Analytical Electron Microscopy Operation or Job Amphibole Fiber Concentrations, fiber/cc Range of Individual Samples Mean (+ SE) of Individual Samples Median of Individual Samples Mill F o r e m a n (2) 18.4 - 33.7 26.0 + 7.7 26 .0 Ge ne ral Laborer (2) 9.0 - 36.6 22.8 + 13.8 22.8 Crushe r Op erator (2) 9.0 - 15.6 12.3 + 3.3 12 . 3 Harding e Operator (2) 33.6 - 102.7 68.1 + 34.5 68.1 Wh e el er Operator (2) 18.2 - 25.5 21.9 + 3.6 21.9 Packer (2) 31.9 - 41.8 36.8 + 4.9 36.8 Packer Serviceman (2) 7.3 - 26.7 17.0 + 9.7 17.0 Pa ck ho us e Foreman (2) 13.6 - 16.2 14.9 + 1.3 14.9 Fork Lift Op erator (1) 36.0 - 36.0 36.0 - -- 36.0 Ma c h i n i s t (1) 24.9 - 24.9 24.9 - -- 24.9 Welde r (1) _ 9.9 - 9.9 -------------------------- --------------- 9 .9 - -- 9 .9 Concentrations are for positively identified asbestos fibers of all lengths ( ) Number of samples analyzed SE Standard error v TimeWeighted Ave rage 2 5.0 2 3.6 12.0 7 0.6 22.9 36.0 11. 1 14.6 36.0 24.9 9 .9 100 mMmm - "' j; ' ' f .. .TABLE A-5 ' -t '* -j_r~ Summary of Respirable Dust Exposures in Mine Operations Operation or Job Range of Individual Samples *D , R e s p i r a b l e Dust C o n c e n t r a t i o n s - rag/mJ M e a n (+ SE) of individual Samples M e d i a n of Individual Samples TimeWeighted Average T r a m m e r (3) S c r a p p e r M a n (3) L a b o r e r (1) D r i l l e r (3) C a g e m a n (1) R e p a i r m a n (1) R e p a i r m a n H e l p e r (1) Mechanic (1) 0.13 - 0.95 0.58 - 1.72 0.58 - 0.58 0.54 - 1.42 0.23 - 0.23 1.14 - 1.14 0.86 - 0.86 0.42 - 0.42 0.64 + 0.26 1.29 + 0.36 0 . 5 8 + --0.99 + 0.26 0 . 2 3 + --1 . 1 4 + --0 . 8 6 + --0 . 4 2 + --- 0.85 1 .57 0 .58 1.00 0.23 1.14 0.86 0.42 0.64 1 .29 0.58 0.98 0.23 1.14 0.86 0.42 101 ( ) Number of full shift samples collected SE Standard Error TABLE A-6 Summary of Respirable Dust Exposure in Mill Operations Operation or Job Mill Foreman (2) Respirable Dust Concentrations - Range of Individual Samples Mean (+ SE) of Individual Samples Median of Individual Samples O mg/m TimeWeighted Average 0.52 - 0.64 0.58 + 0.06 0.58 0.58 General Laborer (1) 1.14 - 1.14 1.14 + -- 1.14 1.14 Crusher Operator (2) 0.60 - 1.13 0.87 + 0.27 0.87 0.85 Hardinge Operator (2) 0.65 - 1.56 1.11 + 0.46 1.11 1 . 09 Wheeler Operator (2) 0.45 - 2.73 1.59 + 1,.14 1.59 1.56 Packer (2) 0 .39 - 0.95 0.59 + 0.07 0.50 0.59 Packer Serviceman (2) 0.40 - 0.44 0.42 + 0.02 0.42 0.42 Packhouse Foreman (2) 0.22 - 0.28 0.25 + 0.03 0.25 0 .25 Fork Lift Operator (3) 0.23 - 0.44 0.35 + 0.06 0 .37 0 .35 Car Liner (1) 0.31 - 0.31 0.31 +_ -- 0.31 0.31 Bulk Car Loader (1) 0.25 - 0.25 0.25 + -- 0.25 0.25 Millwright (2) 0 .16 - 4.64 2.41 + 2.24 2.40 2.37 Instrument Repairman(2) 0.58 - 0.59 0.59 + 0.01 0.59 0.59 Machinist (1) 0.40 - 0.40 0.40 + -- 0.40 0.40 Millwright Helper (1) 2.95 - 2.95 2.95 + -- 2.95 2.95 Sheet Metal Worker (1) 0.50 - 0.50 0.50 + -- 0.50 0.50 Oiler (1) Welder (1) 0.72 - 0.72 0.75 - 0.75 0.72 + -- 0.75 + -- 0.72 0.75 0.72 0.75 ( ) Number of samples (all full shift samples) SE Standard Error 102 TABLE A-7 Summary of Respirable Free Silica Exposures in Mine Operations Respirable Free SO2 Conce ntrations - m g/m3 Operation or Job Range of Individual Samples Mean (.+ SE) of Individual Samp1es Median of Individual Samples TimeWeighted Average Trammer (3) Scrapper Man (3) 0.012 - 0.025 0.012 - 0.012 0.020 + 0.004 0.012 + 0.000 Laborer (2) 0.000 - 0.012 0.006 + 0.006 Driller (2) Repairman's Helper l Mechanic (1) 0.000 - 0.024 0.014 + 0.007 (1) 0.000 - 0.000 0 . 0 0 0 - ----I 0.000 - 0.000 j 0.000 - ----- I J___________-- ---- ( ) Number of full shift samples collected 0.024 0.012 0.006 0.014 0.000 0.000 0.020 0.012 0.006 0.014 0.000 0.000 SE Standard error 103 TABLE A-8 Summary of Respirable Free Silica Exposures in Mill Operations Respirable Free Si0 2 Concentrations - mg/m^ Operation or Job Range of Individual Samples Mean (+ SE) of Individual Samples Median of Individual Samples TimeWeighted Average Mill Foreman (2) 0.013 - 0.014 0.014 - 0.000 0.014 0.013 General Laborer (1 ) 0.014 - 0.014 0.014 - ----- 0.014 0.014 I Crusher Operator (2) 0 . 0 1 2 - 0 .028 0 . 0 2 0 + 0.008 0.020 0.020 i Hardinge Operator (1) 0 . 0 1 2 - 0 . 0 1 2 0 . 0 1 2 - ----- 0.012 0.012 Wheeler Operator (1) 0 . 0 1 2 - 0 . 0 1 2 0 . 0 1 2 - ----- 0.012 0.012 i Packer (7) 0.000 - 0.015 0.019 + 0.002 0.013 0.010 1 i Packer Serviceman (2) 0.000 - 0.013 0.007 + 0.006 0.007 0.007 n Packhouse Foreman (2) 0.013 - 0.016 0.015 + 0.001 0.015 0.014 i's Fork Lift Operator (1) 0 . 0 0 0 - 0 . 0 0 0 0 . 0 0 0 - ----- 0.000 0.000 Car Liner (1) 0 . 0 0 0 - 0 . 0 0 0 0 . 0 0 0 - ----- 0.000 0.000 Bulk Car Loader 0.016 - 0.016 0.016 - ----- 0.016 0.016 ( ) Number of full shift samples collected SE Standard error '"I tj 104 TABLE A-9 Dust Co n c e n t r a t i o n s in Mine Operations as Determined Summary of Airborne by Midget Impinger/Optical Microscopy Techniques SE Standard error <f Millions of particles per cubic foot of air mppci 105 DEPARTMENT OF H EALTH , EDUCATION, AND W ELFA R E PU8LIC HEALTH SERVICE CENTER FOR DISEASE CONTROL NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY ANO HEALTH ROBERT A. TA FT LABORATORIES 4 6 7 6 CO LU M B IA PARKW AY. CIN CINN ATI. OHIO 4 5 2 2 6 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. $300 THIRD-CLASS DHEW (NIOSH) Publication No. 80-115