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Dangerous Dust: The Silicosis Hazard in American Industry

by Leonard Greenburg, M.D.

Executive Director, Division of Industrial Hygiene, New York State Department of Labor

December 1936


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The silverware manufacturing industry WIS selected for study by the U. S. Public Health Service in order to obtain knowledge of an occupation for which the dust content of the air was lower than in the granite stone industry, and in which the quartz content was low. In silverware manufacturing the average dust content of the air is about five million particles per cubic foot of air and the quartz content 1.7 percent. This dust is produced in polishing the product.

The study failed to reveal any cases of silicosis. It is interesting to note that a similar study concluded in textile manufacturing corroborated the silverware manufacturing study in revealing no cases of this disease.

From the foregoing it becomes apparent that silicosis is an insidious disease, its victim often completely unaware of its gradual onset until the final stages have been reached. This slow and unperceived development complicates workmen's compensation. In many states compensation claims must be filed within one year after the onset of disease. Clearly this is impossible in most cases of silicosis, where the date of onset is not known. Further, the unsuspected cases of silicosis make it difficult to set up an insurance scheme covering this occupational hazard because at the inauguration of the program they constitute an accrued liability for wllich no financial reserves have been set aside.

The labor turnover in certain dusty trades is high. After working in one plant long enough to develop early silicosis, of which they are not aware, workers often transfer to another establishment where, after a relatively brief interval, they are stricken with disabling silicosis. Should the first employer, the second employer or both jointly pay this compensation bill?

A just compensation plan for silicosis victims can only be drawn and administered after careful study of the problem and its many factors. Hasty legislation may produce far-reaching evils.

In view of the fact that silicosis cannot be cured and that the advanced stages are practically always complicated by a terminal tuberculosis, the importance of prevention is apparent. The improved techniques of modern industry were developed in response to a demand for a greater output of fabricated goods and materials. It is important to realize, however, that these production methods have in certain instances increased old health hazards and brought about new ones. Studies demonstrate that dust production in granite stone cutting and in rock drilling has been increased tremendously since the introduction of pneumatic tools.

The first method of preventing silicosis is to substitute harmless materials for those known to be harmful. Obviously if we could remove quartz from all industrial operations we could at one stroke eliminate the silicosis hazard. This is, of course, impossible. But it is possible to substitute other materials for quartz in certain industrial operations. Many foundries employ sand (practically pure quartz) in cleaning castings by sand blasting. It has been shown that the substitution of small fragments of steel, known as steel grit or shot may in many cases be used with equal efliciency. This substitution does not completely eradicate the health hazard, since a certain quantity of sand adheres to the surface of castings made in sand molds and it is this sand which the cleaning process is designed to remove. Studies reported by Dr. C.E. A. Winslow of Yale University and the writer made in sandblast rooms showed a dust concentration of 970 million particles per cubic foot of air when using sand as the abrasive as compared with 155 million particles when using steel grit.

A second example is the substitution of abrasive wheels made from synthetic abrasives (practically no quartz) for those made from natural sandstone (about 95 percent quartz), practically eliminating the hazard.

Another method of dust control is by the use of water. This has been done with considerable success in anthracite coal mining, as demonstrated in the following table:

 
Dust Concentration
Millions per Cubic Foot
 
Operations Controlled Uncontrolled Control Measure
drilling 33 568 wet drilling
loading coal or rock 32 636 material wetted while loading
preparation of coal 24 380 wet breakers
handling coal 1.2 17 wetting coal and empty cars
(Data from the U.S. Public Health Service)

 

The results are obvious—in each case a very real reduction in dustiness by simple, inexpensive means.

 

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