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FILE NAME Talc TALC DATE 1960 Nov DOC TALC104 DOCUMENT DESCRIPTION Medical Journal Article - Problem Areas in Pneumoconiosis Reprinted from the Archives of Environmental Health November 1960 Vol 5 pp 428-437 Copyright 1960 by American Medical Association Problem Areas in Pneumoconiosis MORRIS KLEINFELD M.D. and JACQUELINE MESSITE M.D. New York The residual problems relating to the pneumoconioses are numerous In essence however these can be grouped into 3 main areas namely 1 the establishment of causal relationship 2 the evaluation of the degree of disability and 3 the medicolegal factors These 3 categories are interdependent and interrelated The Establishment of Causal Relationship The establishment of causal relationship in any one case requires a knowledge of the occupational chest disease as well as precise information concerning the industrial environment wherein the alleged exposure has occurred It is in the latter area that the practicing physician is often handicapped since he does not usually have sufficient information about the industrial environment This is readily understandable for rarely does he have the opportunity to visit the work site acquaint himself with the industrial processes the materials used and the degree of protection afforded Further- more evaluation of the work environment often cannot be accomplished by mere inspection but requires detailed chemical and physical analysis of the borne dust and parent compounds to which the worker is exposed Only infrequently does the physi- cian avail himself of a state industrial health agency to obtain assistance in this area There are numerous instances which can be utilized to demonstrate how knowledge of both the industrial environment and the occupational chest disease in question is important in determining causality The following examples will serve to illustrate the importance of knowing some of the factors relating to the industrial environ- ment 1. Significance of Particle Size of the Dust group of workers were exposed to a parting compound which contained 50 free silica The dust counts taken of the general air and at the breathing zone of the workers at the various operations con- sistently disclosed air concentrations well above the maximum allowable limit of 5 mppcf The average duration of exposure of these workers was 12 years However in spite of the high exposure there were only minimal respiratory complaints Clinical examination of these workers did not reveal any notable abnormalities referable to the cardiorespiratory system Fig Posteroanterior view of chest of Patient 1 a silica brick molder who had 18 years of exposure fields The roentgenogram shows clear lung Received for publication Aug. 10 1960 Director Division of Industrial Hygiene New York State Labor Department Dr. Kleinfeld Chief Medical Section Division of Industrial Hygiene New York State Labor Department Dr. , Messite 64/428 PNEUMOCONIOSIS aREAS No significant incidence of positive ray findings for silicosis was obtained Figure 1 is a chest roentgenogram which is representative of the group The principal operation of this worker Patient ) was that of a molder for 18 years He was asymptomatic and no abnormal clinical findings were observed The absence of clinical and roentgeno- graphic evidence of silicosis in the light of a persistent exposure to excessive concentrations of free silica required further analysis of the dust particularly for particle size Of significance the size of the silica particles was predominantly above 10... which is beyond respirable range The lack of consistency between the environmental and medical data is therefore explained by the latter observation This study emphasizes what is not often appreciated namely that exposure to a known toxic dust does not necessarily result in the development of a disabling pneumo- coniosis 2. Importance of the Physical Characteristic of the Despite similar degrees of exposure to talc dust in two different mills the workers associated with one plant showed appreciably more respiratory com- Fig Posteroanterior view of chest of Patient 2 a miller of tremolite talc for 32 years Note diffuse fibronodular infiltrations in middle and lower lung fields bilaterally The left cardiac border is partially obscured by the infiltration plaints and ray evidence of pulmonary talcosis as compared with the other The only discernible difference was in the phys- ical characteristic of the talc dust In the plant where the workers exposure was to the fibrous rather than the granular variety of talc a significantly higher incidence of dyspnea productive cough and chest pain occurred Similarly the ray findings of the chest were more abnormal in this group The reason why the fibrous variety is more pathogenic is not readily apparent Figure 2 is the chest roentgenogram of Patient 2 a tale miller who was exposed to a fibrous variety of dust for 32 years and shows a diffuse fibronodular infiltration bilaterally This is in contrast to Figure 3 which is the chest roentgenogram of Patient 3 a talc miller who had been exposed to a granular variety of talc for 33 years and shows only increased bronchovesicular markings Figure 4 shows a sample of the fibrous variety of talc dust and this is significantly different from the granular type as seen in Figure 5 3. The Importance of Knowing the Details of the Worker's Not infrequently the physician while obtaining an occupational history is misled by his patient's job title For example a worker may have a designated title as a plater which would imply that he works with plating solutions and is exposed to various Fig Posteroanterior view of chest of Patient 3 a miller of granular talc for 33 years Increased bronchovesicular markings are seen Kleinfeld 65/429 ARCHIVES OF ENVIRONMENTAL HEALTH Bae Pas SF hin REg ee Fig Photomicrograph of crushed talc ore showing square and oblong particles and spicules characteristic of tremolite tale ^ 725 ve 5 Fig Photomicrograph of crushed talc ore showing aggregates of granular or scaly particles X 725 solvents and metals required for plating operations However he may also do some polishing with a sandstone wheel and thus be exposed to silica dust To avoid such pitfalls the physician should make inquiry as to the exact details of his patient's work At times it is rewarding to know also what other operations are carried on in the vicinity of the patient's area It is possible that a worker may be exposed to dust from an adjacent operation even though he is not performing it The following case illustrates the need for knowing the details of a worker's job Patient 4 a year white man was hospitalized because of shortness of breath wheezing and pain in the right side of his shoulder of 5 days duration His past history revealed that he had been suffering from chronic lung disease for about 15 years and for the past 6 years had been troubled by asthmatic attacks In addition he had had a weight loss of about 30 lb. during the 3 months prior to admission Occupational history disclosed that the patient had been retired for 6 years but prior to this 66/430 he was a steam fitter a job his building maintaining and but also the cleaning of them requiring not only repairing furnaces He performed this dusty job often without taking any protective measures such as use of a mouth respirator Clinical examination showed a thin elderly white man who was cyanotic dyspneic and somewhat disoriented The eyes reacted to light and accommodation The chest was emphysematous and the patient was using his accessory respiratory muscles during breathing The lungs were hyperresonant There were dry rales scattered throughout both lung fields The heart was not enlarged and the rhythm was regular There was a systolic murmur Grade 1 at the apex The blood pressure was 135/75 There were no abnormal abdominal findings The extremities did not show any atrophy or wasting The nail beds were cyanotic The peripheral pulses were felt The pulse was 108 and regular the respirations 28 and temperature 99.4 F. Laboratory data Urinalysis showed a 1+ pro- teinuria and occasional white cells in the sediment The hemoglobin was 12.4 gm % white blood count 9,500 cmm with a normal differential Sedimentation rate was 26 mm BUN 12 100 cc CO 22.6 mEq sodium 139 potassium 4 and chlorides 89 mEq Sputum culture was negative Vol 5 Nov 1960 PNEUMOCONIOSIS AREAS not only a knowledge of the clinical and differential diagnostic aspects but also of the epidemiology of the disease as is indicated by the following case history 1. The Importance of Knowing the Epidemiology of the Industrial Dust Diseases.The following case demonstrates the importance of knowing the epidemiology of the disease Fig Posteroanterior view of chest of Patient 4 a maintainer and cleaner of furnaces for approximately 20 years A mottled infiltrate is seen in the upper left upper lobe The lower lung fields are emphysematous and a patchy area of pneumonia Chest roentgenograms taken on admission showed a displacement of the mediastinal structures to the right with a considerable amount of hazy mottled infiltrate in the left upper lobe having both a reticular and a miliary pattern The lower lung fields were emphysematous and there was a patch of infiltrate in the left base The appearance sug- gested a probable pneumoconiosis associated with a patchy area of pneumonia Fig 6 The patient was given oxygen bronchodilators and antibiotics and showed some improvement initially However his mental state gradually deteriorated and he became completely disoriented Three weeks after admission he suddenly died An autopsy was performed and showed primarily an extensive pulmonary anthracosis bronchopneumonia bilaterally and pulmonary emphysema predominantly right The extensive anthracosis seen in this patient's lung is probably due to his chronic exposure to carbonaceous material while cleaning the fuel burn- ers which he had done for at least 20 years Similar cases have been reported by others particularly among superintendents who did extensive cleaning of coal stoves without using proper pro- tective measures Patient 5 a year Negro woman was found to have on a routine chest roentgenogram taken at the local health clinic an abnormal chest ray characterized by micronodules scattered bilaterally throughout both lungs She was asymptomatic and her past medical history as well as systemic review was nonrevealing Occupational history disclosed only one episode of dust exposure this was at the age of 23 when she was employed for 13 months in a steel plant where she used a compressed air hammer to remove hot sand from cast iron During this operation she was exposed to heavy concentrations of dust for the first few months after which time a water spray was instituted to suppress the dust She disclosed also that she had lived for a period of 2 years about 6 miles from a beryllium plant where her husband was employed During this period her husband brought his contaminated clothes home for frequent washing Physical examination showed a appearing Negro woman of good color The physical examination did not show any abnormalities Lab- Fig Posteroanterior view of chest of Patient 5 a Negro housewife who had a nonoccupational exposure to beryllium from laundering con- taminated work clothes Micronodules are seen diffusely scattered bilaterally as is compatible with berylliosis The following will illustrate the importance of having a broad knowledge of the occupational dust diseases in the determination of causal relationship This implies Hemie Hemie Messur Messur Hemie Hemie Hemie Messur Messur 67/431 ARCHIVES OF ENVIRONMENTAL HEALTH oratory work including histoplasmin COCcidioidin tuberculin and Kveim skin tests peripheral blood study total protein determination and blood cell count showed no abnormalities The chest roentgenogram showed micronodules diffusely scattered bilaterally The heart size and pulmonary artery segments were normal The costophrenic angles were diminished Fig 7 The history and chest roentgenogram suggest that she most likely has berylliosis which has been reported to have occurred from such type of exposure.,, The chest ray was compatible with berylliosis although sarcoidosis cannot be en- tirely excluded 2. Similarity Between Occupational and Nonoccupational Pulmonary Diseases.Disea-ses.- The following cases of pulmonary disease observed in a father and son illustrate the problems of differential diagnosis between occupational and nonoccupational pulmo- nary diseases Patient 6 a year white man complained of a nonproductive cough of several years duration which had progressed only slightly There were no other symptoms Past history and systemic review were noncontributory The occupa- tional history revealed that he had been a miner of granular type of talc for 19 years He had no history of any other occupational dust exposure Fig Posteroanterior view of chest of Patient 6 a miner of roentgenogram granular talc for 19 years shows diffuse micronodular The and calcific densities distributed throughout both lung fields It is compatible with a diagnosis of histoplasmosis which is endemic in the area where this patient resides t 68/432 Fig Posteroanterior view of the chest of Patient 7 the year son of the miner in Figure 8 showing similar findings He had a minimal talc exposure for two years Clinical examination revealed a developed nourished man of good color There were no abnormal physical findings A chest roentgenogram taken during a plant survey showed diffuse micronodular and calcific densities distributed throughout both lung fields Fig 8 Patient 7 18 years of age was asymptomatic His past history and systemic review were nonrevealing Occupational history showed that he had been employed for 2 years in the same plant where his father worked but was assigned to the insecticide department where the talc exposure was minimal Physical examination showed no abnormal findings A chest ray taken during the same plant survey also showed minute calcifications and a few micronodular densities Fig 9 These two cases illustrate some of the problems in differential diagnosis between occupational and nonoccupational disease Among the differential diagnoses to be considered are pulmonary talcosis histoplasmosis and siderosis In the father who has had a potentially hazardous exposure to talc dust for 19 years the practicing physician may entertain a diagnosis of pulmonary talcosis However the presence of a similar chest roentgenogram in the son whose ex- posure to talc was only minimal makes such a diagnosis highly unlikely Furthermore the roentgenograms are somewhat atypical for pulmonary talcosis following exposure to the granular variety of talc In the latter type of exposure one observes more of a hazy mottling and interstitial infiltration Vol 5 Nov. 1960 PNEUMOCONIOSIS areaS with basilar involvement primarily Since the area where these people reside is endemic for histoplasmosis this would seem the more likely diagnosis in both of these workers 3. The Significance of Knowing the Incubation Period of the Occupational Chest Diseases 1938 a chest roentgenographic study of 126 workers in 7 plants engaged in the manufacture of cleansing powders was performed by the Division of Industrial Hygiene in cooperation with the Division of Tuberculosis New York State Department of Health The manufactured product contained for the most part a finely ground quartz compound silex and other siliceous materials of a slighter degree of toxicity as feldspar and volcanic ash Although this was primarily a chest ray survey all the workers were questioned as to previous occupational exposure to dust The results showed that 18 or 14.3 of the employees had roentgenographic find- ings compatible with silicosis in all stages Of these 4 had ray evidence of silicotuberculosis The mean age of the positive cases and the mean duration of exposure were 40 and 9.8 years respectively Of particular interest is the fact that 3 of the workers with roentgenographic evidence of silicosis had been employed in this industry for 4 years or less and had had no previous occupational exposure to silica and other dust The mean age of these 3 cases was 30 years Figure 10 is the chest roentgenogram of a year laborer Patient 8 who was exposed to this dust for 4 years The roentgenographic picture shows nodular infiltrations throughout both lung fields This study serves to illustrate the fact that excessive exposure to a highly siliceous material of inhalable particle size can produce roentgenographic evidence of silicosis in a shorter period of time than the 10 or more years usually required This has been corroborated by other investigators For example Strutek describes roentgenographic manifestations of silicosis in 3 workers exposed for a period of 14 years Kleinfeld Fig Posteroanterior view of chest of a laborer Patient 8 who had an industrial ex- posure to a fine cleansing powder for 4 years Nodular infiltrations are seen widely distributed bilaterally to cleansing powders containing 96 silica and % oxalic acid Although the latter author alludes to the role of oxalic acid as responsible for the rapid development of silicosis it is noteworthy that this acid was not an ingredient of the cleansing powders manufactured this Division by the plants surveyed by It is worth stressing that a diagnosis of pneumoconiosis should not be excluded from the differential diagnosis simply on the basis of a relatively short exposure to a known fibrogenic dust Evaluation of Degree of Disability Experts in the field recognize that the evaluation of the degree of disability in workers with pneumoconiosis requires a detailed analysis of their environmental ex- posure a complete medical and occupational history clinical evaluation appropriate roentgenograms pulmonary function tests and in certain instances a pathological examination of lung tissue Usually none of these approaches by itself will suffice It is generally agreed that there is no substitute for the clinical examination but 69/433 ARCHIVES OF ENVIRONMENTAL HEALTH as a single parameter it has its limitations It must be correlated with the environmen- tal data chest roentgenogram and other appropriate tests to be of value both diagnostically and as a basis for evaluating disability When tuberculosis develops in a silicotic person one can say with certainty that he is completely disabled even though this may be at variance with his clinical picture The utilization of the chest roentgenogram alone as a basis for disability evaluation is similarly unreliable It is noteworthy that Greenburg who studied a group of rock drillers in New York State reported that approximately fourth of the men whose chest rays showed ad- vanced silicosis had no complaints A similar observation was noted in granite cutters.3 In contrast a worker may be seriously disabled by persistent breathless- ness and yet have little or no roentgenographic evidence of pulmonary disease This has been particularly emphasized by British investigators Such cases are often diagnosed as bronchitis and emphysema although either diagnosis may be difficult to prove clinically This lack of clinical and radiographic correlation has been seen especially in workers who have been employed for many years at a coal face or in iron and steel foundries Hence the absence of characteristic roentgenographic abnormalities should not exclude the asso- ciation of a patient's complaints with his occupational exposure If a worker manifests respiratory impairment and gives a history of sustained exposure to a dust one must consider seriously the causal relationship of the industrial exposure to the pulmonary dysfunction even if the patient's chest ray reveals only minimal changes When nodular shadows are seen on the chest roentgenogram it is appreciated that the size of the nodularity may bear no direct relationship to the patient's pulmonary symptoms of his degree of disability except in rare instances where single or conglomerate masses are critically located and 70/434 produce obstruction of a bronchus resulting in respiratory symptoms In general it is the dispersion of the nodularity which bears a closer relationship to the patient's clinical picture For example micronodules if dispersed throughout the lung parenchyma are more likely to produce respiratory symptoms than conglomerate masses localized peripherally The latter is illustrated by the following case Patient 9 a year man was hospitalized because of a painful right knee of one week's duration Three days before admission the knee became hot and swollen There was no history of recent trauma At the age of 15 he developed an osteomyelitis of the lower third of the right femur which healed after several months He has been in excellent health since Surgical history review of systems and family history were noncontributory The occupational history re- vealed that he had been a street laborer for 27 years digging trenches with a pick and shovel Occasionally he operated a pneumatic drill and hammer Physical examination showed a developed nourished man of good color With the exception of minimal crepitus of the right knee and a depression along the lower portion of the right femur the site of the old osteomyelitis the physical findings were essentially negative Fig Posteroanterior view of the chest of Patient 9 a street laborer who dug trenches and intermittently used a pneumatic drill for 27 years Vol 5 Nov. 1960 PNEUMOCONIOSIS AREAS Routine blood chemistry studies peripheral blood count and urinalysis were normal Chest rays revealed a normal cardiac con- figuration with multiple shadows of varying sizes in both lung fields Fig 11 The radio- gram suggested metastatic pulmonary carcinoma Urologic studies including retrograde pyelography were normal dicated it is more important to obtain repeated . pulmonary measurements in the same individual and have his initial data serve as a control for subsequent comparison This is particularly of value for such tests as maximum breathing capacity where The pain and swelling in the right knee subsided with bed rest and the patient returned to his former job completely asymptomatic A chest roentgenogram taken 6 months later showed no change from the film and the patient appeared to enjoy excellent health The clinical impression of metastatic pul- monary carcinoma strongly entertained during the patient's hospital course appeared less likely in view of his lack of changes in months of 1 clinical picture after nine observation 2 serial chest roentgenograms 3 blood picture including blood counts and chemistries and 4 gastrointestinal and genitourinary ray series A more probable diagnosis was pneumoconiosis causally related to his occupation It is of a particular interest in this case that the relatively large circumscribed masses distributed in the lung fields especially peripherally were not accompanied by any clinical abnormalities There is a growing belief that the pulmonary function approach provides the best yardstick for evaluating disability There is a great need to utilize a group of pulmo- nary function tests particularly maximum breathing capacity timed vital capacity pul- monary ventilation at rest and after exer- the range of normal is very wide Similar widespread values were observed by Wright in a study of maximum ability for sustained physical energy The latter study revealed a variation of % above and below the mean maximum capacity for exercise as measured in a group of normal persons In essence one must conclude that neither the conventional methods of examination nor the more refined methods of pulmonary function determination can serve by themselves or collectively as a consistent reliable yardstick for the evaluation of degree of disability This is particularly true for purposes of workmen's compensation where the evaluation of disability is usually based upon the worker's inability to earn full wages in the work at which he was last employed or at which he was exposed to the hazard responsible for the disease rather than a physiologic basis of dysfunction The phy- sician must therefore be familiar with other factors which are important in evaluating his patient's disability such as the requirements of the job the worker's attitude toward his work his intelligence and neuro- muscular coordination A worker's over capacity for his particular job is not cise and oxygen diffusion measurements across pulmonary capillary bed to evaluate predicated purely on his physical ability but in addition is dependent upon his psy- alterations in pulmonary physiology Nonetheless these tests may not reflect the patient's clinical status or his ability to perform at his job This is particularly true in the early stages of pulmonary dust disease It has been repeatedly shown that it is often impossible to demonstrate subnormal pulmonary function in men who have extensive simple discrete nodular sili- cosis and not infrequently persons who have extensive conglomerate silicosis show only a moderate deviation from their normal respiratory capacity As some have in- chological attitudes such as incentive his mental capacity and his neuromuscular function to develop a skill and efficiency for a particular operation These factors in many circumstances may compensate for the physiologic incapacity The physician should whenever possible obtain an intimate knowledge of the worker's job requirements Unfortunately the practicing physician often lacks such information and he is thus handicapped in his appraisal of the worker's ability to perform at a specific job Since the physician is Kleinfeld 71/435 ARCHIVES OF ENVIRONMENTAL HEALTH usually placed in a position of determining whether or not a person is physically competent to carry on a particular job it is evident that he must obtain complete information regarding all of these factors if he is to appraise the worker's disability with any degree of adequacy Medicolegal Factors The previous discussions have been concerned primarily with medical considerations in the diagnosis and disability evaluation of pneumoconiosis However the physician must also be aware of the legal technicalities in order to deal with problems of compensation in these discases Perhaps the greatest difficulties arise from those provisions in present workmen's compensation laws which fail to recognize the medical facts These include the legal concept of disability the limitation of compensation to total disability and the time limits for filing claims Legal Concept of Disability in 20 states that define the term in their workmen's compensation laws is expressed either as inability to earn any wages in the employment where last employed or inability to perform any further work in the occupation in which the employee was engaged or inability to earn similar wages in other suitable employment It is noteworthy that the legal concept of disability is based upon ability to per- form work or earn wages rather than physiologic loss of function As already mentioned the ability to perform work is influenced by factors other than those which affect physiologic capacity These include incentive skill and economic need Pertinent to the latter there have been cases in which medical consultants of workmen's compensation boards have recommended awards for medical total disability on the basis of clinical disability and significant dust exposure Yet because the compensa- tion benefits for wage loss are insufficient to meet their needs these workers prefer to remain at their jobs thereby receiving no compensation except medical payments It 72/436 is noteworthy that in cases of hearing loss awards are being made on the basis of physiologic loss rather than on earning ca- pacity Limitation of Compensation to Total Disability In 20 states partial disability for pneumoconiosis is not compensable However before any adequate basis for compensation for partial disability in pneumoconiosis can be established it is essential that the physiologic concept of disability be accepted and that practical and adequate criteria for the evaluation of such disability be developed and applied Present tests of pulmonary function do not accurately assess the degree of disability Bronchospirometry can establish the physiological integrity of individual portions of the lungs However it is difficult to perform often unsatisfactory and therefore impractical for the purpose of disability evaluation for compensation At best pulmonary function measurements provide only an estimate of the degree of disability in pneumoconiosis Time Limit for Filing Probably the most inequitable provision from the point of view of the physician is the time limitation which excludes claims not made within a legally specified interval after exposure About 18 of the state compensation laws specify such an interval which varies from 1 year to 5 years This is unreasonable particularly where compensation is limited to total disability In New York State for example the law requires that a worker be totally disabled by pneumoconiosis To obtain compensation a person must file a claim within 2 years after he leaves the employment wherein his dust exposure allegedly occurred This application of the statute of limitation is inconsistent with the known natural history of the disease Clinical and epidemiological studies clearly indicate that the fibrotic process once initiated may be progressive even in the absence of further exposure Disability therefore may not appear until long after the person has left the dust exposure Vol 5 Not 1960 PNEUMOCONIOSIS AREAS New York State recognizing that some diseases may develop long after a worker has left a hazardous work area has since 1947 excluded from the statute of limita- tions claims filed for certain occupational diseases such as those due to arsenic benzol and ionizing radiation However only one pneumoconiotic agent namely beryllium has been listed in this group It would be desirable that the time limitation be re- moved in the cases of claims filed in connection with diseases due to other pneu- moconiotic agents which produce progressive pulmonary diseases In essence the solution to the medico- legal problems in pneumoconiosis is dependent to a large extent upon more extensive epidemiological studies of these diseases and the development of adequate and practical criteria for the evaluation of disability It is through such pursuits that the necessary data on which to base strong arguments for equitable legislative provisions in compensation for pneumoconiosis will be accumu- lated Summary and Conclusions Three major problem areas in pneumoconiosis are discussed these include establishment of causal relationship evaluation of the degree of disability and medicolegal factors In view of the similarities between occu- pational and nonoccupational pulmonary diseases the physician in order to establish causality must obtain detailed information of the industrial environment wherein the alleged dust exposure occurred Frequently this requires in addition to inspection of the work site detailed chemical and physical analysis of the borne dust and parent compounds to which the worker has been exposed Cases are cited to illustrate the importance of knowing such factors as the particle size and physical characteristics of the dust and the details of the worker's job The establishment of a causal relation- ship in any one case of pneumoconiosis is also dependent on a complete knowledge of these diseases Examples are given to dem- onstrate how a knowledge of the epidemiology incubation period and differential diagnosis of these diseases is essential in establishing causality Neither the conventional methods of ex- amination i.e. clinical roentgenographic or pathological nor the more refined methods of pulmonary function determination can by themselves serve as a consistently reliable yardstick for disability evaluation in a case of pneumoconiosis Until such time as more precise criteria for disability measurement in these diseases are developed the physician frequently must combine all of these approaches before arriving at a de- cision The legal concept of disability namely the inability to perform work or earn wages further complicates the problem of evaluating disability This is particularly true since the ability to perform work is influenced by other factors such as incentive skill and economic need in addition to the physiologic capacity The limitation of compensation to total disability and time limits for filing claims are additional factors which present problems to the practicing physician A dis- cussion of these factors is included 80 Center St. REFERENCES 1. Eisenbud Berylliosis J. M. et al Occupational Indust Hyg & Toxicol 282 Sept. 1949 2. Strutek .: Silicosis in Workers Packing Cleansing Power Accelerating Effect of Oxalic Acid ~ asop l^'k ~ esk 343 March 1948 3. Greenburg .: Some Aspects of the Problem of Silicosis Indust Bull 195 June 1936 4. Pemberton .: Chronic Bronchitis Emphysema and Bronchial Spasm in Bituminous Coal Workers A. M.A. Arch Indust Health 13 529 June 1956 5. Wright G. W Disability Evaluation in In- dustrial Pulmonary Disease J.A.M A. 1218 Dec. 24 1949 6. Mayers .: Personal communication to the authors 7. Analysis of Workmen's Compensation Laws U.S. Chamber of Commerce Washington Jan. 1958 8. New York Workmen's Compensation D.C. Law Section 40 Kleinfeld Printed and Published in the United States of America 73/437