Treatment of Occupational Diseases of the Chest

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Treatment of Occupational Diseases of the Chest Part I: Prophylaxis of Silicosis REpORT BY THE SECTION ON TREATMENT" COMMITTEE ON OCCUPATIONAL DISEASES OF THE CHEST" AMERICAN COLLEGE OF CHEST PHYSICIANS

S

be called in to insure the continued safety

ILICOS IS IS A DISEASE WHICH VARIES

greatly from one country to another, from one industry to another, from one occupation to another, and from one individual to another. In its simplest form, it is limited to an asymptomatic focal fibrosis of the lungs. In its more advanced forms, and especially when complicated by emphysema, cor pulmonale or tuberculosis, there is need for symptomatic and specific treatment. Such advanced degrees of uncomplicated or complicated disease are fully preventable and it is the purpose of this report to present methods which have been proven to be effective in the prevention of the disabling phase of this disease.

of the working environment. Many difficulties occur in dust control and one cannot generalize in such a matter. Most major industrial plants and mines already have dust control programs that are practical and compatible with the economics of the industry. No one as yet has defined a universally acceptable safety standard with respect to silica dust. At the 22nd annual conference of Government Industrial Hygienists, 1960, (United States of America) the following maximal allowable concentrations were recommended: Silica:

Million particles per cubic foot of air Quartz High (above 50% free silica) 5 Medium (5-50 % free silica) 20 Low (below 5 % free silica) 50 Cristobalite (above 5% free silica) 5 Amorphous 20

DUST SUPPRESSION

Control of dust-containing significant amounts of free silica is the all-important defense against the development of silicosis. Substituting wet methods for dry, non-silica materials for silica when possible, good housekeeping and adequate exhaust ventilation where free silica materials still must be used, as well as tested respiratory protection, will solve or mitigate serious silicosis hazards. The efficiency of a dust-control program is dependent both on the engineers who design such dust suppression systems, as well as the cooperation of the workmen in minimizing the dust produced at the working area and in conforming with regulations designed to protect them. Judging the dustiness of a working environment demands a highly specialized technical procedure. The first objective is to eliminate perceptible dust. However, even when a working atmosphere appears dustless to the eye, dust counts of the air sampled in the area may show high concentrations of dust particles in a toxic size range. A hygiene engineer must, therefore,

This is a mere guide, but the following comments are relevant. For quartz, all depends on particle size. If the particles are all above 10 micra, the dust will be virtually harmless, Between 1 and 3 micra, quartz particles produce typical silicosis. If particles are below 1 micron, atypical silicosis will follow and this may be very dangerous. The standard for cristobalite is inadequate. Cristobalite and tridymite* are about five and ten times as injurious as is quartz and appropriate precautions should be taken. The standard for amorphous silica is applicable to only the naturally occurring minerals such as opal or tripoli. The synthetic amorphous silica dusts are all submicron in size and some are exceedingly toxic while others are relatively inert.

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*N 0 separate standard has been suggested for tridynute.

Volume 41.J No.3 March, 1902

OCCUPATIONAL DISEASES OF THE CHEST

It is wise always to aim at the lowest possible dust levels, regardless of the recommended standards. Episodes of intense exposure may occur unexpectedly and unknowingly and even a low exposure may be a threat to some unduly susceptible persons. In the ultimate analysis, the safety of a working environment is proved by the clinical result; i.e., non-development of silicosis in new recruits and retarded progression in those previously exposed. Even when no clinical or radiographic signs of silicosis develop there may still be demonstrable silicosis at necropsy. Dust control achievements are not permanent. The program must be a continuing one through the lifetime of the industrial employee. Dust counts, chemical analysis of the dust, and dust sizing should be performed at reasonably frequent intervals. Dust sampling, however, is useless unless corrective measures are instituted where indicated. MEDICAL CONTROL

Three phases should be considered; i.e., the pre-employment and preplacement, the periodic and the post-employment examinations. Basically each of these is a complete medical test with emphasis on different facets of health. Pre-employment and Preplacement Examinations: The objectives of the initial examination are to ascertain fully the personal health and occupational histories of the applicant and to determine whether any physical lesions exist which would disqualify him for employment in a dusty trade. At the pre-employment and preplacement examinations certain records should also be made to serve as a standard of comparison by contrast with which the onset of relevant pulmonary disease may be recognized. The occupational history should fully include all periods of exposure to gases, fumes, mists, smokes or dusts. When a positive history of such exposure is admitted, records should be secured to determine accurately the extent and duration of such exposures.

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In the personal history any health factor which may later impair the physical integrity of the prospective employee should be discovered. Particular attention should be given to a history of tuberculosis, chronic or recurrent bronchitis, allergies, particularly where asthma has been a feature, previous pneumonia or pneumonitis, especially if recurrent, rheumatic fever with cardiac involvement, renal disease, etc. A detailed smoking history and other personal habits should be recorded. The physical examination should extend literally from head to foot. Occupations which involve exposure to dusts usually also are dangerous in other respects, so that medical certification should cover vision, hearing, reflexes, over-all intelligence and attitude. The upper respiratory tract is as important as the lower at this stage. Good general physique and posture are part insurance against the risks pertinent to dusty trades. Endocrine balance, absence of hernia, good digestive system, absence of renal disease are relevant. More attention will, of course, be given to the thorax and its contents. An exercise tolerance test should be conducted. Records which should be made, besides a report of the history and physical examination, should include body weight, chest circumference and anteroposterior diameter, breathing excursion, adequate x-ray examinations and urinalysis. Ventilatory lung function studies, electrocardiographs, blood counts, and skin testing (e.g., tuberculin and fungal) are desirable. With preplacement examinations, the criteria for rejection of a candidate for a particular job vary tremendously from one dusty trade to the next and depend entirely on the adequacy of the dust suppression or control. When it is recognized that a hazard still exists, then it still is necessary to prevent employment of persons who cannot screen and eliminate inhaled silica dust as well as they should. Persons with definite chronic bronchitis and emphysema always must be carefully placed where they will have little or no further exposure to free

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AMERICAN COLLEGE OF CHEST PHYSICIANS

silica dust. Persons with tuberculous lesions should not be exposed to hazardous concentrations of silica dust. Workers who already have some silicosis, even though slight in degree, need to be so placed that additional significant silica exposure will not occur.

Periodic Examination: The periodic examination should be repeated annually. It need not be as comprehensive as the initial, but should focus attention more specifically on the lungs and heart. It is important to record all intercurrent illnesses, even if they at first seem irrelevant or trivial. Even important events are soon forgotten by both the employee or the physician. An entry should also be made about the nature of the service performed in dusty environments during the interval since the last examination. Not infrequently, the doctor's notes may be the only reliable source of information about silica exposures. Systematic notation of symptoms becomes of great importance. Exertional dyspnea may be the first clue. Cough soon follows. Chest pain may become relevant. Physical signs may be scanty at the start of silicosis, but careful note-taking may, by comparison with observations made later, bring into prominence the slow evolution of a change which would be too subtle to detect in any other way. Particular attention should be given to changes in the configuration of the thorax, the range and type of breath excursion, changes in the quality of breath sounds, adventitious sounds, sound conduction, etc. The radiograph and electrocardiogram may furnish important early clues. The hematocrit may rise steadily. Ventilatory studies may reveal incipient changes in lung volume or air trapping. The tuberculin skin test should be repeated if previously negative. If the least suspicion arises that silicosis may have commenced or that tuberculosis or some other pulmonary or cardiac disease has started, the employee should be subjected to more thorough study, includ-

Diseases of

the Chest

ing sputum examination and cultures. He should be informed of the reason for such more detailed examination and be apprised of the result. During successive periodic examinations the physician will have opportunity to explain to the employee the nature of silicosis, to disabuse his mind of unwarranted fears, but also to alert him concerning relevant dangers. The employee should also be encouraged to maintain a program of physical exercise. Post-Employment Examinations: The employee who has been exposed to silica dust should be encouraged to continue undergoing periodic examinations at least once a year, since silicosis may manifest itself many years after cessation of exposure to dust. If the employee has already been certified to have contracted silicosis in an incipient degree (1st stage) he should be re-examined biennially since silicosis may progress without further dust exposure and complications such as tuberculosis, cor pulmonale, emphysema, etc. may arise later. The scope of the physical examination will, of course, be appropriate to the problem to be inquired into. Early attention to such complications may help to abort further progression to disability. Should the employee die it is most important that a necropsy be performed and that the heart and lungs in particular be carefully studied. The lungs should be subjected to chemical and petrographic study to determine the quantity and type of dust which has accumulated. It may be questioned whether a necropsy can rate as part of a prophylactic program against silicosis. It certainly is very relevant. Only by knowing precisely what exposure to the dust in the industry in question is capable of doing will it be possible to ensure the full protection of all employees still exposed. If the dust reaction is revealed to be more severe than was expected, the industrial hygiene engineers will have a clear mandate to further efforts to suppress dust exposure. If tuberculosis becomes a major feature, the source of infection must be identified and eradicated.

Volume 41) No.3 March, 19c>2

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Aluminum Administration: If an industry is unable to control the production of silicosis in its working force, due to peculiarities of the raw materials, production methods, inadequacies of design or maintenance of dust control units and the lack of appreciation of dust suppression by the workers individually or collectively, then the use of specially prepared aluminum powder inhalation is suggested as a third aid in silicosis prevention. Experimental investigations in Canada, the United States of America, England and South Africa have demonstrated that aluminum may (a) prevent silicosis; (b) arrest the progression of immature lesions and facilitate their resolution; (c) prevent the development of complications. Aluminum has no effect on mature fibrotic nodules other than to limit their extension. Certain clinical studies of the application of aluminum inhalations in the develop-

ment and progression of silicosis in humans have shown a favorable trend in silicosis control where dust and medical control programs failed to eradicate the silica hazard. Aluminum inhalations should never be considered as a substitute for adequate dust control. COMMITTEE ON OCCUPATIONAL DISEASES OF THE CHEST PETER A. THEODOS, Chairman ARTHUR VORWALD, Vice-Chairman G. W. H. SCHEPERS, Secretary SECTION ON TREATMENT HOWARD S. VAN ORDSTRAND, Chairman MATTHEW J. DROOOWSKI OSCAR FEINSILVER JOHN W. G. HANNON THOMAS N. HUNNICUT, JR. TRACY LEVY G. W. H. SCHEPERS JOSEPH F. TOMASHEFSKI JAMES H. WALKER

i\MNIOTIC PULMONAR\:" EMBOLISM Arnold and associates report a case of amniotic pulmonary embolism. The pathogenesis of this condition requires: the trapping of amniotic fluid under pressure and entrance Into the maternal venous circulation. The lungs show embol1zatlon ot the arterioles and capillaries with alveolar edema and hemorrhage. The heart may be enlarged due to right heart strain and faUure. The clinical picture Is that of acute respiratory distress and shock during

or Immediately following delivery. Hemorrhagic phenomena mayor may not ensue. The diagnosis Is prlmarUy clinIcal, supported by the x-ray and electrocardiographic finds. The characteristic roentgen findings consist of bilateral perihUar ln1l1trattons, the distribution of which 1a related to the capillary distribution found In the lung. ARNOLD,

H. R.,

GARDENER,

J. E.

"Amniotic Pulmonary Embolism,"

AND GOODMAN, P. H.: R"Jiol., 77:629, 1961.

CONGENITAL LOCALIZED EMPHYSEMA Congenital localized emphysema Is a rare but dlstlnct clinical and pathologic entity which appears to be due to a defect In the development of the bronchial wall. A single lobe, segment or rarely, an entire lung, may become massively distended and produce serious compression of normal lung

tissue. Surgical removal of the abnormal pulmonary tissue Is the recommended treatment. CAMPBBLL,

D.,

BAUBR,

A. J.

AND HEWLB1T,

genital Localized Emphysema,'· ]. Tho, 4 1: ~ 7 ~, 1961.

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T. H.,: "ConC",tliofl. S.".,