Dust: The Silicosis Hazard in American Industry
by Leonard Greenburg, M.D.
Executive Director, Division of Industrial Hygiene, New York State
Department of Labor
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
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.
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.
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:
Millions per Cubic Foot
|loading coal or rock
||material wetted while loading
|preparation of coal
||wetting coal and empty cars
(Data from the U.S.
Public Health Service)
The results are obviousin each case
a very real reduction in dustiness by simple, inexpensive means.