Document 7Zv5wYymXZN7LopNvBmZOVyR

50 Twenty-first Congress--National Safety Council a proper staff, and not by some enthusiastic pa-son who has not been trained for the work. Why not use more registered nurses in the smaller plants? The registered nurse is much better qualified to interpret a physician's plan of medical service than any lay attendant. Much depends upon the physical condition of the employees. I am of the opinion that the physician, fay reason of his professional attainments, is best qualified to handle some of the problem cases among employees. Mental symptoms, brought about by worry over home affairs, quite often produce accidents. In many cases the fear and worry of sickness in the family can be greatly allayed by a talk with the doctor or the nurse. Many of these cases have come under my personal observation. It should also be absolutely the part of the physician to say when a man dial] return to his regular employment after injury, and this decision should not be in fluenced m the slightest by its possible affect on any "no-lost time accident" contest or record. These contests are proper and have brought about outstanding results in the reduction of lost-time irequaicy figures. However, there hare been cases of injured employees being urged unduly to return to some farm of work merdy to prevent the marking up of a lost-time accident. Nothing should be allowed to inter fere with the employee's welfare. The 'physician has even* motive to return the employee to his regular work as promptly as possible, but his higher duty is to conserve both the physical and economic welfare of the employee as well as die employer. The safety director has need of the medical service, and the two should earnestly co-operate and seek to bring about a mutual feeling among the employees. Both departments are striving by all possible means to prevent economic waste chargeable to the disabilities and hazards of industry* TUESDAY AFTERNOON SESSION October 4,1932 The delegates first attended an informal luncheon, and Uien gathered lor the after noon meeting in a Joint Session with the Metals Section. This session was devoted to a symjjosium on the dust problem in Industry. Chairman Greenburg immediately introduced the first speaker. ^^ - __ The Effects of Inhaled Mineral Dusts ' By LEROY XL GARDNER Director, Saranac Laboratory for the Study of Tuberculosis, Saranac Lake, N. Y. As long as mat Itavc worked in stone it has been aiqtrcciated that an unusually large pro:onion of them suffer from disease of the lungs. It was natural to assume that such disease would be caused by the dust generated, and this belief was strength ened by the discovery of black, grey or red pigments in tlie lungs, sometimes accom panied by the formation of scar tissue. The term, pneumonokoniosis was introduced to describe the lung pigmented in this manner. With further observation pathologists attempted to classify various forms of pneumonokoniosis on a basis of the type of dust inhaled and such names as anthracosis, siderosis, chacicosis and even byssinosis and tobaccosis made their appear ance. It was recognized that some forms of the disease were attended by severe symptoms and result in death but there was no correlation between the clinical and jiathoJugical pictures and the causative dust. Finally, statistical study demonstrated that of all kinds of industrial dusts silica generally produced a definite type of disease with a characteristic pathological lesion and complex of symptoms. Industrial Health Section 51 Today the clinical entity known as silicosis is one form oi imeumonokoniosis which is quite clearly defined. Moreover, within the last three or four years asbestos dust has also been shown to produce another specific type of reaction attended by symp toms differing in some respects from silicosis. The other forms of pneumonokoniosis still lack complete definition. The wide spread use of radiography has brought together a mass of descriptive data from indi viduals exposed to many kinds of occupational dusts but these findings have not yet liecn correlated with lithological anatomy, chemical studies of tltc tissues and de tailed analyses of industrial atmospheres. There is a tendency to assume that many of these pulmonary changes arc due to Use action of silica jierhaps modified by the chemical cominments of the dust We shall only be in a position to speak with assur ance about them when the pure types of dust and their various combinations have been studied in human beings or in experimental animals. For the sake of clarity no mention has been made of the infections which so fre quently complicate some forms of pneumonokoniosis. In the prebactcriolugical era of medicine the use of such terms as "grinders* consumption" and "miners' phthisis" reflects the popular association of pneumonokoniosis with tuberculosis. The names were justified both hv clinical and pathological observation for it has liecn subse quently shown that, in silicosis at least, a super-imposed tulierculosis may cause death in ]*rhaps 75 per cent oi the cases. Some observers even go so faT as to state that silicosis itself docs not develop unless the lungs are previously damaged bv a latent tulicrculous infection. This is probably an exaggeration, for typical silicosis can be jrroduccd in the experimental animal by the inhalation of silica without infection. The role of asbestos dust as an excitant of tulwrculous infection is not as dear rut as that oi pure silica. While there are numerous reports of death in asbestosis due to a terminal tuberculosis, nevertheless surveys of living workers have failed to demonstrate any excess of such infection. Simple anthracosis is said to prevent the progression of tulicrculous infection. Statistics from coal mining districts do show a tuberculosis rate much lower titan that "normal" for the age group. As yet corrobo rated experimental proof of protective action of coal against tuberculous infection is lacking. Not only the tubercle bacillus but other bacteria seem to develop with special facility* in the tissues previously damaged by silica. For example, the imcumonia rate among silicotic native laborers of South Africa is many times that in non-silicotic natives living under similar conditions. In coal miners, likewise, pneumonia is a common and often fata) complication. What has 1ecn said of the effects of inhaled inorganic dusts would indicate that the reaction of the tissues is not merely a response to mechanical irritation by par ticulate matter. Today it is generally accepted that the injury is chemical in nature and that only certain of the common types of industrial dusts possess properties capable of exciting reaction. In the cases of silica and the silicate of magnesium or asbestos the slightly alkaline Itodv fluids probably effect a slow solution of the dust particles liberating silica in colloidal form. This substance irritates the connective tissue cells which respond by multiplying. The result is an overgrowth of the sup porting framework dements at the expense of the more delicate cells specialized for specific functions. For tltese two types of dust the character and form of the pathological changes has been carefully worked out In zfficorir the essential tissue change consists of nodules of connective tissue which develop first in the lympoid tissues situated in the drainage apparatus of the lungs. These nodules interfere with the physiological removal of foreign bodies and subsequently inhaled particles accumulate in the framework of the lung itself. Such reaction gradually decreases the normal elasticity of the organ and encroaches upon its functional elements. As a result the cardinal symptom of the disease, dyspnoea or shortness of breath develops. Because of the excessive amounts of scar tissue formed in the lungs the right side of the heart