Dust: The Silicosis Hazard in American Industry
by Leonard Greenburg, M.D.
Executive Director, Division of Industrial Hygiene, New York State
Department of Labor
It will be observed that the tuberculosis
rate for grinders and polishers in this ax factory was twelve
times that of the other employes of the factory and that the ax
factory district had a tuberculosis rate of 200 as compared with
150 for the state as a whole. This table also shows that the contribution
of tuberculosis deaths from a local industry or group of industries
may adversely affect the mortality rate of a general population
group. In other words if the high incidence of tuberculosis associated
with certain occupations could be reduced, a reduction might be
expected in the general tuberculosis rate for the entire area.
The most valuable
silicosis data come from detailed studies in selected industries,
but only a few such studies have been made. The U. S. Public Health
Service through its publication has made available the greater
part of this knowledge in the United States. Among the industries
in which the dust hazard has been studied in detail are: the scouring
powder industry, granite stone cutting, and silverware.
of scourit1g powder contain quartz as the abrasive agent, which
may constitute 75 percent or more of the finished product. The
quartz is usually very Enely pulverized in order to prevent scratching;
hence the dust is potentially very dangerous. Dr. Eugene S. Kilgore
of San Francisco writing in the lournal of the American Medical
Association summarizes his experience with cases of silicosis
arising in this industry. In one case which resulted after eleven
months of occupational exposure, the patient experienced marked
shortness of breath in attempting to climb one flight of steps.
Dr. Kilgore cites the cases of six employes who worked from ten
to twenty-seven months in this industry, five of whom were dead
from silicosis at the time of his publication. This occupation
may be regarded as one of the most serious types of exposures,
closely paralleling quartz rock and quartz sand grinding. Several
years ago cases of silicosis were reported among New Jersey workers
engaged in grinding and pulverizing sand. This pulverized material
is almost identical with that used in the making of scouring powder
and the sand pulverizers were found to develop silicosis after
about two years' exposure.
to the best available studies, approximately one to two years
represents the shortest time required for the development of silicosis.
It is conceivable for the disease to develop in a shorter period
when exposure to pure quartz dust is encountered but clear cut
evidence on this question is lacking.
In 1922 F.
L. Hoffman in cooperation with the National Tuberculosis Association
published the first study of the dust hazard among Barre granite
workers. In 1929 after several years of study the U. S. Public
Health Service brought out an exhaustive report on the same problem.
This study includes determinations of the quartz content in the
dust, the actual clustiness of the atmosphere, as determined for
workers at different tasks, morbidity and mortality statistics
of workers engaged at various occupations and X-ray studies of
the lungs of workers.
of a normal chest;
a worker not exposed to dangerous dust
The creeping shadow of silicosis
in a doomed worker's lungs
is the center of the granite stone industry. Blocks of granite
are taken from the quarries, cut to dimensions, surfaced, carved
and lettered. This material is used for building purposes and
for tombstones. The average quartz content of Barre granite is
35 percent. The Public Health Service study showed that the dust
content of the air varied from five to forty-eight million particles
per cubic foot, depending on the particular industrial process
IN the following table which presents the
findings of l this study the workers are grouped in four classes
according to dust exposure. The table presents average dust exposures,
the period of time in years required to produce early and advanced
silicosis and the tuberculosis deathrate for each group. The relationship
between the amount of dust, the time required for the production
of silicosis and tuberculosis is obvious.
||Average Dust Count
||Years to Develop Silicosis
||Years to Develop Silicosis
||Tuberculosis Deathrate per