Document gbrZ0VR279E3o3eVDJv6O5vJ3
FILE NAME Talc TALC
DATE 1947
DOC TALC097 DOCUMENT DESCRIPTION Medical Journal Article - The Dust
Hazard in Tremolite Talc Mining
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THE DUST HAZARD IN TREMOLITE TALC MINING
LEONARD GREENBURG
From time to time the attention of the Division of Industrial
Hygiene has been drawn through compensation claims to incapacitating fibrosis in talc workers Since silicate dusts of which talc is one have been considered relatively innocuous in the opinion of most authorities the single exception being asbestos , the occurrence of these cases has naturally raised several questions obvious question as to whether this incapacity has resulted from talc exposure alone and the second and more interesting question as to whether industrial hygienists with few exceptions have erred in considering asbestos to be the only injurious silicate dust
In an attempt to answer these questions the study here reported was undertaken It consisted of an investigation of the talc industry
and an examination of talc miners and mill workers in northern New
York State St. Lawrence County made as a joint enterprise of the Division of Industrial Hygiene of the State Department of Labor and the Division of Tuberculosis of the State Department of Health
Nature of talc Talc is a hydrous magnesium silicate with the formula H2Mg3
SiO3 4 composed according to Ladoo of about 63 per cent SiO2
32 per cent MgO and 5 per cent H2O It is usually a secondary mineral resulting from the alteration of other magnesium silicates or carbonates While its own silica is present in the combined form most talcs mined commercially contain varying amounts of such impurities as quartz calcite dolomite iron oxide etc.
Talc has a characteristic soapy feeling and a pearly luster It may be pure white silvery white gray or green and when impure yellow brown or reddish The most common commercial variety is a massive foliated or granular type but it may also occur in a micaceous or in a
fibrous form
* From the Division of Industrial Hygiene New York State Department of Labor
New York
Leonard Greenburg M. D. Adelaide Ross Smith M. D. New York State Dept. of Labor and William Siegel M. D. New York State Dept. of Health
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The
482
YALE JOURNAL OF BIOLOGY AND MEDICINE
Soapstone is a closely related substance being essentially an impure talc and when pulverized it may be used for the same purposes
Tremolite which is a calcium magnesium silicate changes over to talc
It may be mined with it and subsequently ground and sold as talc
Geographical distribution
The United States produces about 65 per cent of the world's supply of talc the leading states in its production being Vermont New York California North Carolina and Georgia
Industrial uses of talc
According to the Minerals Year Book 1938 of the United States Bureau of Mines the use of talc and soapstone is steadily increasing
Ladoo states that at least 60 different uses for talc have been noted
though most of them are of minor importance Its value depends chiefly on its usefulness as a filler inert extender dusting powder and absorbent In 1921 according to Ladoo the marketed ground talc production in this country was industrially distributed as follows paper 38 per cent paint 23 per cent prepared roofing 18 per cent rubber 9.5 per cent textiles 4 per cent toilet powder 2.5 per cent other uses
5 per cent
The other uses for which ground talc is adapted are as a filler in soap in foundry facings in insulating compounds in dry lubricants as a filler in cotton textiles in the dressing and manufacture of leather as a cleaning and polishing agent for rice peas coffee beans peanuts etc in making colored crayons as a filler in the windowshade cloth as a dusting agent in making candy chewing gum etc and as an ingredient of concrete plastics and insecticides
Since 1921 there has been a marked increase in its use in the
ceramic industry Fourteen thousand more tons of talc and related
materials were sold in 1937 than in 1936 and about 10,000 tons of this
increased amount went to the ceramic industry where talc is chiefly
used as a constituent of glazed wall tile
Review of literature on the effects of talc dust Experimental studies During the last ten years a certain amount of experimental work with talc dust has been reported but on reviewing this literature most of the inhalation experiments are found to have
been of insufficient duration to be helpful in regard to the probable
effect of continued industrial exposure
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The
a ~
an impure
purposes
date ver to talc
ye
is talc ay,ik J
rld's supply New York
Se
nited States
increasing een noted le depends owder and ground talc
wspaper
ent rubber
other uses
s a filler in
1 dry lubri-
ufacture of
offee beans
indowshade ; and as an
use in the and related tons of this
c is chiefly
amount of
1 reviewing
nd to have
e probable
DUST HAZARD IN TALC MINING
483
In 1931 Haynes included talc in a series of dusts studied for their reactions on guinea Twelve pigs were dusted two hours daily except Sunday for a fortnight The author saw no sign of pulmonary
damage but found that bronchial and lymphatic removal occurred unusually briskly He concludes that the substances dissolved from talc are of a low degree of toxicity but are sufficiently obnoxious to neighboring tissues to cause the removal of cells containing them
St^...berin 1934 studying the cellular response of lymph nodes to various dust suspensions introduced into the lymphatics found that talc caused no apparent cellular proliferation within the lymph nodes after five days After 108 days the nodes were still normal and showed
no increase in connective tissue
Fossel in 1935 reported experiments in which guinea were exposed to the inhalation of talc for one hour daily over a period of eight weeks No significant tissue changes were seen
Bethune in 1935 was able to produce pleural adhesions in cats and dogs by blowing commercial talc into the pleural cavity Miller and Sayers quoted below found that adhesions were not related to the subsequent behavior of the dust
Fienberg in 1937 having observed granulomas from the surgical use of talc experimented with the injection of this substance in mice and obtained subcutaneous granulomas in these animals
Miller and Sayers in 1936 reported studies in which talc was included among the dusts with which the intraperitoneal reaction in guinea was studied They found that it produced an inert reaction That is to say the injected dust was not absorbed neither did it initiate a cellular proliferation In interpreting the significance of inert reac-
tions the authors conclude that such dusts should be considered as
potentially harmful
Gardner summarizing experimental work on silicate dusts at the Saranac Laboratory said at the Fourth Saranac Laboratory Symposium
on Silicosis 1939 a few silicates like true talc and some of the
clay minerals have provoked chronic inflammation of the lungs but
this reaction has tended to retrogress after several months No pro-
gression to a stage of true fibrosis has been observed within periods of one to two years and there is no indication that the progression will
occur
In 1939 Policard reported an experiment in which he dusted
white rats with foliated industrial talc three hours a day for twelve
Acts
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484
YALE JOURNAL OF BIOLOGY AND MEDICINE
days The intensity of the exposure was high He found that the dust
was irritating to the upper respiratory tract and produced a marked
dyspnea In the lungs of animals sacorfifibcreod ntcwhoi anacdutsiex deamypshayfsteermianhaalnad-
tion began he found dilatation
exudative alveolitis Many animals died spontaneously with pulmonary
and foci of bronchopneumonia The short duration of the
congestion
concerning the possibility of
experiments did not permit any conclusion
postoperative pulmonary fibrosis
McCormick and Ramsey in 1941 reported
inflammation caused by talc in two cases And pSecrhiutlozneaanldgrWainlulloimaatmosusin 1942 injected intraperitoneally in guinea-
series of seven commercial talcs with different carbonate priagtsioas Animals were sacrificed at intervals ranging from ten days to
fifteen months In all cases the pathological histology showed the holding of talc particles in a local area by phagocytic cells of the
macrophage and giant cell type Progressive fibrosis was not found
The fibrosis which occurred was only enough to hold and limit the space for storing the foreign material The greatest amount of fibrous tissue developed in the presence of the two talcs which contained the least
carbonate and the most talc and tremolite respectively
Clinical reports Talc fibrosis as an occupational disease has received
attention in this country only within the past ten years Policard says that it was in 1896 that the question of the action of industrial talc dust on the human lung was first considered At that time Thorel a
pathological pathologist of Nuremberg published the results of the
examination of the lung of a tuberculous woman patient of forty who had worked for many years in soapstone dust According
ytoeaProslicard Thorel demonstrated the presence of cells containing soapstone dust in the cavity and walls of certain alveoli and disclosed the existence of formations more or less nodular resulting from the accumu-
lation of cells filled with talc Other nodular formations of a tuberculous
nature were present and Thorel pointed out a combination of tuber-
culous and pneumoconiotic lesions In 1915 according to Policard Hayhurst stated that work in
talc dust favored and exaggerated tuberculosis but the basis for this
opinion is not known
the conclusion that
Zanelli in 1931 quoted by Teleky came to
talc dust though belonging to the family of silicates ought to be con-
sidered dangerous and likely to produce typical pneumoconiotic lesions
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The
at the dust | a marked fter inhalaysema and
pulmonary
tion of the
ossibility of
stoperative
"cases And
in guinea-
carbonate
ten days to
showed the cells of the not found it the space brous tissue ed the least
has received icard says dustrial talc
e Thorel a
pathological of forty . According aining soap-
isclosed the the accumutuberculous on of tuber-
at work in asis for this
clusion that t to be coniotic lesions
DUST HAZARD IN TALC MINING
485
Merewether1 in 1933 reported the cases of 11 rubber workers
exposed from 10 to 32 years to French chalk a fine granular variety of talc dust who showed diffuse interstitial fibrosis by roentgen examination without clinical evidence of anything more than a peribronchial increase in fibrous tissue Thirteen additional workers with exposures of from 4 months to 48 years were examined and reported upon the following year,,confirming the original findings
In 1933 a report was made by Dreessenof examinations of a number of workers in silicate dusts including 57 men exposed to tremolite a hydrous calcium magnesium silicate containing no free silica The findings in this group were as follows more fibrosis than usual 67 per cent stage pneumoconiosis 26 per cent second pneumoconiosis 2 per cent normal lungs 5 per cent
Dreessen described the stage pneumoconiosis as similar to that produced by cement dust softer than that resulting from silica dust a diffuse fine generalized fibrosis . . . chiefly confined to the lower thirds of the lung fields
In 1935 the same author together with Dalla reported on
the effect of exposure to dust in two Georgia talc mills and mines The dust involved was again a calcium magnesium silicate containing no
free silica It was present in excessive amounts over one and half
billion particles per cubic foot in some operations the particle size averaging less than 1 micron Sixty workers were examined Among these 22 33 per cent showed pneumoconiosis 8 in stages two or
three The conclusion was reached that exposure to talc dust was either
too severe in the Georgia study or that this talc was a more dangerous dust than that previously studied No particular relationship between
talc exposure and tuberculosis was demonstrated
Middleton in 1936 referred to an unpublished case of Cunningham's in which pneumoconiosis was found in a talc grinder who had been employed for nine years He also mentioned an autopsy by Sand in 1910 on a woman exposed to talc dust in which not much reaction
was found
In 1938 Nuck and Szczepnaski19 reviewed the literature on talc fibrosis and added several cases of their own They concluded that this
type of pneumoconiosis resembled asbestosis more than silicosis
At the International Conference on Silicosis at Geneva in 1938
Riddell reported the results of the examination of 37 workers engaged in grinding talc ore Thirteen showed fibrosis resembling silicosis
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The
486
YALE JOURNAL OF BIOLOGY AND MEDICINE
Gardner on the same occasion said that of 300 films of talc workers which he had examined about 50 showed some evidence of
pulmonary reaction which in 17 suggested nodulation From a survey of the literature it appears that while experimental
studies have hitherto been inconclusive clinical studies have tended to
indicate that talc dust is capable of producing injurious pulmonary
changes
Compensation claims for disability due
to talc dust in New YoYrk ork State
The cases which originally drew the attention of the Division of Industrial Hygiene to disability resulting from exposure to talc dust are summarized below Six such cases have occurred during the past
few years One originated in the manufacture of talcum powder one in the shoe industry and four in talc mining and milling In one case
there had been significant previous exposure to dust probably con-
taining free silica Five of the cases were fatal In 5 cases summaries
are available as follows
Case I. Aged three The claimant had worked for 12 years operating a talcum powder mixing machine not provided with exhaust ventilation for dust control The talc used was found by the Division of Industrial Hygiene to
contain less than 0.5 per cent of free silica The dust concentrations at this work
ranged from 13.9 to 34.8 million particles per cubic foot For three or four years before quitting the job the claimant had complained
of cough with expectoration Examination of the lungs showed moist r^les at the bases The vital capacity was 2,500 normal estimated as 4,000
Roentgen examination of the lungs showed an increase of bronchial markings in the lower and middle fields with areas of increased density resembling lipiodol
or calcific deposits in both lung fields In hospital a diagnosis was made of emphysema and chronic bronchitis with
acute exacerbation
Case II Aged forty For 22 years the claimant had worked as a bed laster in a shoe factory White shoes were manufactured during about five months of the year and at these times he used talc freely dusting it on the shoes to prevent soiling of the white leather The powder used was analyzed by the Division of Industrial Hygiene and found to contain no free silica
For seven years before quitting work he complained of cough dyspnea and increasing weakness His condition finally necessitated hospital treatment
Physical examination showed the presence of dyspnea cyanosis and clubbing of the fingers Examination of the lungs revealed dullness on both sides with
diminished fremitus and breath sounds
Roentgen examination of the chest showed marked confluent hazy mottling with nodular densities uniformly distributed The right ventricle was hyper-
trophied cor pulmonale
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The
4
i
ns of talc
TS
vidence of
perimental aigaides
tended to
pulmonary
Division of > talc dust g the past
wder one
In one case
bably con-
summaries
rs operating
ntilation for
| Hygiene to at this work
I complained
noist r^les at
) ial markings
ling lipiodol
onchitis with
ed as a bed g about five on the shoes
lyzed by the
L
dyspnea and
atment
and clubbing
h sides with
azy mottling : was hyper-
DUST HAZARD IN TALC MINING
487
The diagnosis was chronic pulmonary fibrosis and emphysema The case terminated fatally nine months after admission to the hospital
Case III Aged forty The claimant had worked as a talc miner for 15
years with 8 months exposure in other mines 10 years previous to his talc
exposure His illness began five years before death with shortness of breath and a productive cough He quit work two years after the onset of symptoms because of increasing weakness and was admitted to a sanatorium
Physical examination showed an emaciated individual who looked chronically ill The vital capacity was 1,800 normal estimated as 3,000 The lungs showed dullness over the middle thirds r^lesabove second rib anteriorly and posteriorly throughout Five specimens of sputum were negative for the tubercle bacillus
The temperature was normal
Roentgen examination showed extensive bilateral fibrosis with infection probably tuberculous and this was the diagnosis
Case IV Aged thirty For 21 years the claimant had worked in talc mines as mucker driller and foreman For two years before quitting work he had noticed cough shortness of breath and pain in chest He was easily fatigued These symptoms caused him to enter a hospital for treatment
Physical examination revealed no lung abnormalities but showed cardiac
hypertrophy hypertension and evidence of nephrosis Roentgen examination of the chest showed fine nodulation through both
lung fields below the fifth posterior rib more marked in the central lung field an increase in hilum shadows and cardiac hypertrophy
The clinical diagnosis was early silicosis with probable infection hypertensive disease and severe nephrosis
The case terminated fatally Case V. Aged fifty The claimant had worked in talc mines for 17 years with a previous exposure of 10 years in zinc and iron mines Illness began six years before death with cough and dyspnea Following the initial symptoms he developed pain in chest and hemoptysis and sought hospital treatment
Physical examination showed an emaciated individual appearing chronically ill The fingers were slightly clubbed The chest expansion was limited Examination of the lungs showed dullness on the right below the seventh spine with r^les and diminished breath sounds The sputum was positive
Roentgen examination showed a fine miliary type of increased density on the left a mass of increased density in the right middle lung field with evidence of excavation and heavy fibrosis at the right base
The clinical diagnosis was probable silicosis complicated by tuberculosis Death occurred 21 months after admission to the hospital
A study of talc miners and millers in St. Lawrence County New York
Scope of study In the course of this investigation studies of operations and dust concentrations were made by engineers of the Division
of Industrial Hygiene in three talc mines and five talc mills From seven
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488
YALE JOURNAL OF BIOLOGY AND MEDICINE
U.S.
by
plants 221 men received an initial roentgen examination In the case of
protected 28 of these individuals who showed positive lung findings at the end
of ten months a follow examination was made which included a
second roentgenogram a medical history and physical examination of
be
may the chest and a detailed occupational history
ed,spat
The roentgen examinations were made with a 200 milliampere
machine mounted on a truck belonging to the Division of Industrial
and
party Hygiene Patterson speed screens were used and exposures were
made at a inch distance and with an exposure time of tenth
of a second
third
Type of talc involved The type of talc produced in St. Lawrence
a
County is of the fibrous variety known as asbestine It is noted for its
by
Medicne clear whiteness and is used chiefly as an ingredient in the manufacture of
paint and tile With it is found tremolite magnesium silicate
CaMg3 SiO3 mineral similar in appearance occurring in a
of
fibrous or asbestiform state which in the course of time changes over
Library to talc Gardnerreports that anthophyllite another fibrous silicate is
also present in the talc deposits of the St. Lawrence County region
Analysis of representative samples of talc from two of the mines in the region submitted by one of the mining companies shows the follow-
National
ing composition
the
Analysis
Sample A
Sample B
of
Total silica
68.24
57.50
colection Calcium oxide
Aluminum oxide Iron oxide
2.72
5.24 .27 .17
Manganese oxide
.16
the
from Carbon dioxide
Magnesium oxide
24.51
.38 30.20
Calcium carbonate
0.23
copied Sulfur trioxide
trace
was Ignition loss
3.65
5.13
99.35
99.05
page
* Includes both free and combined silica
this
Free silica content The free silica content of commercial talc as
on
found in industrial use is very low Schulz and Williams report that
material of 51 samples analyzed quartz was not found in 25 traces of quartz
The were present in 25 while one sample showed a quartz concentration of
3 per cent The free silica content of the talc in the mills and mines
the case of at the end included a ination of
illiampere
Industrial
sures were
tenth
Lawrence
ted for its ufacture of um silicate
tring in a
anges over
. silicate is
gion
e mines in the follow-
B
ial talc as report that : of quartz ntration of and mines
DUST HAZARD IN TALC MINING
489
included in this study was likewise found to be low Six samples from two talc mines taken and analyzed by chemists of the Division of Industrial Hygiene showed 1 per cent or less of free silica Two of these samples were taken from standing accumulations of waste rock two were from recent three- and four waste accumulations and two were from collections of rock destined for the mills Six samples of ground talc from several mills were also analyzed and in each case the silica content was found to be less than 1 per cent Dreessenalso reported little or no free silica in the composition of the talc in this region
Gardner on the other hand found amounts of quartz ranging from 12 to 20 per cent in mineral samples from two mines in this area It is difficult to explain the marked difference between Gardner's findings and those of Dreessenand of ourselves except upon the supposition
that Gardner's samples included some of the bearing stratum overlying the talc deposit proper That such high percentages are not representative however is shown by the fact that material from the
mills where all rock is mixed and crushed showed low quartz percentages
both in Gardner's studies and in our own
Description of the talc mining industry
Mining operations Talc ore is obtained by underground mining Inclined shafts are used with headings to various depths down to about 1100 feet The talc occurs in compact homogeneous seams so that contact with hard rock is limited to that incurred on entering a seam Once a seam is entered there is no exposure to anything but talc until it
becomes necessary to enter another seam Since seams may be worked for
years the amount of drilling in hard rock is very small compared with the amount of drilling in talc
The headings are mined by drift drilling blasting and hand or machine mucking Raising and stoping are resorted to to obtain the ore from pockets All drilling is done dry since every precaution must be taken to avoid wet ore which cannot be milled and is wasted Drilling
crews of one or two men are used the drillers doing their own blasting The ore is then mucked as it is required by the mills It is loaded into muck cars and pushed along the haulage to the shaft where it is dumped into a skip hoisted to the surface and dumped into railroad cars or trucks for shipment to the mills Each mine employs 15 to 17
men underground Dust exposure in talc mining operations The problem of the best
method of control of the dust in talc mines is one which is receiving
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490
YALE JOURNAL OF BIOLOGY AND MEDICINE
the attention of the Division of Industrial Hygiene at the present time Very little dust control was found in the three mines studied Some attempts had been made to remove the dust during drift drilling by means of small home portable units but relatively few of these were in actual use during drilling operations The drillers wore
respirators
Twenty dust samples were taken with a midget impinger at various operations and situations These were counted within ten hours of the time of sampling by means of the power light field technique
and gave the results shown in table 1
The dust counts where no exhaust device was used gave average
dust concentrations as follows for drilling 1,350 for stoping 1,290 for mucking 35 and in the general air 17 million particles per cubic
foot
Talc milling
Milling operations The milling processes in all five mills were found to be essentially alike The ore is shipped to the mills in railroad cars or trucks and is dumped into chutes leading to a jaw crusher From the jaw crusher the talc in most mills passes through disc or roll crushers or both before entering rotary or trommel screens After passing the screens the talc is stored in garners before the final milling operation which takes place in pebble mills The final separation of the finely ground talc is accomplished with air separators from which the material passes to garners which feed bagging machines
The bagging machines utilize open top bags or sacks which fit loosely onto the discharge spout of the machines Hand scoops are used to add or remove talc from the bags to obtain accurate weight The greater percentage of material is bagged in 50 lb. paper bags while some is shipped in larger burlap bags The operators of the bagging machines stack the filled bags on hand trucks and wheel the loaded trucks into railroad cars or automobile trucks for shipment or into the
warehouse for storage
Dust exposure in talc milling operations Dust control in the various mills is confined chiefly to the bagging machines and pebble mills Some
control is also used in several mills at the crushers and material transfer
points Dust samples were taken throughout the mills using the technique already described The samples were taken at the breathing level of the workmen in locations where men are usually stationed
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The
esent time
lied Some
rilling by
w of these
nem
lers wore
ents
me
gut
npinger at
meen
ten hours
technique
ve average
ng 1,290
per cubic
vere found ilroad cars
From the
1 crushers
assing the operation the finely
ie material
which fit scoops are
eight The
ags while
e bagging
the loaded or into the
he various ills Some al transfer
using the breathing
oned
DUST HAZARD IN TALC MINING
491
Table 2 shows the concentrations found at various points throughout the mills Manual handling of the talc produces concentrations in excess of those found at other operations but fortunately there is little manual
handling during normal procedure
TABLE 1
DUST CONCENTRATIONS IN TALC MINES
Operation
Drilling
Stoping
Mucking
Mine A
Dust count
million particles per cubic foot
200
300 75
110 ;
600 2700
B
-
C
A A
5000 1500
150 an
265
^z^k ^z^k
^z^k 100
4000
760 40
50 6
B
35
24
Remarks
Upstream of drill
Rate 2 per minute Downstream of drill
3 upstream Using
exhaust
Same as above Breathing level of helper
Exhaust off
Exhaust off Breathing level of helper downstream
Exhaust of dust collector
Same as above 3 minutes
after drilling stopped
General air stream
Upstream air movement
50 per minute Same as above Air
turbulent Dead drift
Just off main airway Main airway Breathing level driller
top of open stope Dead stope No air
movement
Top of dead raise Bottom of stope drilling
at top Same as above
Top of pile mucking only operation
Downstream of mucker
Same as above
The dustiest operation other than manual handling is that of paper bagging where the average dust concentration for three mills was found to be 163 million particles per cubic foot
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The
:
s
mong talc
|
rosis were
a marked
_
erage dust ncentration
lion particles r cubic foot
a
46 46 50
61
163
93
72 62
in
and in 32 stribution
thanthan
the107
g incidence incidence
2929..99 per
6 showed
DUST HAZARD IN TALC MINING
493
To make clear the fact that talc is a producing dust the dis-
tribution of cases of fibrosis according to age in talc workers and in
a group of carpet factory workers previously examined by the authors is
shown in table 4
TABLE 3 FIBROSIS IN TALC WORKERS BY LENGTH OF EXPOSURE
Years
exposed
S
5-9 10-14 15-19 20-24 25-29 30-39 40-49 50-59
Totals
Age
Less
than 20 20-29 30-39
40-49 50-59
60-69
70-79
Totals
All workers examined
82 32 47 33 10
9 6 1 1
221
Number
_
8 13
2 3 5
-
-
~
Total fibrosis
Cases cent
Fibrosis
Exposure group
per cent
25.0
40.6 6.3 9.4 15.6
-
17.0
39.4
20.0 33.3 83.3
3.1
3.1
100.0
100.0
100.0
14.5
TABLE 4
FIBROSIS IN TALC AND CARPET WORKERS BY AGE
Talc workers
Number
examined
With fibrosis
Number Percent
Carpet workers
Number With fibrosis
examined Number Percent
4 71 72 41 17 13
3
221
6
1
1.4
57
7
9.7
61
7
17.0
57
9
52.9
49
6
46.1
33
2
66.6
3
66.6
32
14.5
266
1 1 4
~
_
6
_
1.6 1.7 8.1
2.5
Fibrosis was present in only 2.5 per cent of all carpet workers and in 4.9 per cent of those 50 years of age and older while it was present
in 51.5 per cent of talc workers in this age group
Ten months after the original roentgen study a second visit was made to the same plants for follow examinations of selected cases At this time occupational and medical histories were taken and chest
examinations were made From the occupational histories it was possible
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494
YALE JOURNAL OF BIOLOGY AND MEDICINE
_ to eliminate those men who had previously been exposed to other types of siliceous dust In this way a group of 18 cases showing marked fibrosis was defined in men who had not worked in any other dusty industry and whose only significant dust exposure therefore had been
to talc
Signs and symptoms Fifteen of the men showing fibrosis worked in the talc mills 3 were miners The proportion of mill workers to miners in the entire group however was approximately 2.3 to 1 showing that fibrosis was relatively more prevalent among millers than miners With one exception the men with fibrosis were all 40 years of age or older and had been exposed to talc dust as noted above for
at least 10 years Thirteen of the 18 had one or more symptoms referable to the
lungs Ten complained of dyspnea 7 of chronic cough and 3 of pain in the chest In addition 5 complained of excessive fatigue
On physical examination all 18 showed limited chest expansion Thirteen showed abnormal lung signs and 13 showed curving of the nails or clubbed fingers In one case cardiac hypertrophy was observed
and in one there was auricular fibrillation
The general appearance of the group struck the examiners as being distinctly different from the appearance of the usual group of first and second stage silicotics who are still able to work The latter usually
present a robust appearance A substantial number of individuals in
such a group are likely to be overweight This was not the case with the talc workers who showed fibrosis None of them was overweight but on the contrary they tended to present an undernourished and drawn appearance It was the impression of the examiners also that dyspnea was unusually pronounced in relation to the extent of the fibrosis seen
in the roentgenograms
Roentgenographic characteristics The type of fibrosis seen in these roentgenograms is very fine and diffuse showing in many cases an appearance of soft haziness to which the term ground glass used in describing certain cases of asbestosis can very well be applied In a number of cases there is in addition a distinctly granular appearance and in some a nodulation which might be confused with silicosis In
certain films soft conglomerations also occur
The fibrosis in these cases tends to be somewhat more marked on the
right side and in the lung fields and bases The hilar nodes show a slight or moderate increase in density Evidence of obliterative pleuritis
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DUST HAZARD IN TALC MINING
495
and emphysema occurs in some cases In a few instances a blurring or
shagginess of the cardiac outline is noticeable
Tuberculosis In the total group of 221 talc workers there were 29
cases 13.1 per cent of primary healed tuberculosis 6 2.7 per cent
of healed infection type tuberculosis and 5 2.2 per cent which were considered on the basis of the roentgen appearances alone to show
clinically significant tuberculosis The incidence of healed primary and infection type lesions is
not remarkable in any way being similar to that found in general in other industrial groups The incidence of clinically significant tuberculosis 2.2 per cent is slightly higher than is found in most industrial groups the average rate found for this condition being about 1.2 per cent Among the 5 individuals with clinically significant
tuberculosis 3 between the ages of 30 and 50 showed minimal lesions
one 45 years of age showed moderately advanced lesions and one 64 years of age showed what was interpreted to be far advanced atypical tuberculosis Among the 18 cases of fibrosis in men exposed only to talc clinically significant tuberculosis appeared to be a complicating feature
in 3 cases 16.6 per cent
Talc plaques A most interesting finding in this group of talc interesting because to these investigators it was new the presence of 14 instances 6.3 per cent of the 221 talc workers
originally roentgenographed of what appeared to be deposits of opaque material on various pleural surfaces These deposits or plaques
are seen on the visceral pleura including the region of the diaphragm and occasionally the pericardium Lateral and oblique views indicate that their location is definitely at the periphery of the lung not involving
the parenchyma
a In size the plaques vary from single appearing deposit of a
few centimeters in length in the region of the diaphragm to massive deposits bizarre in shape extending over a large part of the lung fields They are characterized not only by irregularity of shape but by marked irregularities in degree of density also and by the sharpness of their borders In this series of films the development of these plaques can be traced from small light scarcely noticeable deposits to the extensive
opacities described
It should be noted that roentgen appearances similar to the plaques
herein described were apparently seen in Case 1 where mention is made of areas of increased density resembling lipiodol or calcific deposits in
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496
YALE JOURNAL OF BIOLOGY AND MEDICINE
lung fields Similar appearances have also been noted in another group of workers who were exposed to talc dust in the making of
material for electrical insulation
So far as can be ascertained these deposits bear no relation to any history of previous infection since they occur both with and without such a history Nor are they necessarily associated with other pulmonary pathology The underlying lung tissue may or may not show fibrosis There is no associated enlargement of the hilar nodes in cases showing plaques without fibrosis
An analysis of the group of 14 talc workers who showed these deposits revealed the following facts Their ages ranged from 35 to 77 years and their exposure in the talc industry from 4 to 52 years Ten were mill workers 4 were miners Only one individual gave a history of having had pleurisy None had had empyema In 5 instances no lung pathology other than the plaques was noted A marked degree of fibrosis existed in 7 cases Evidence of clinically significant tuberculosis was seen in one case and of primary healed tuberculosis in
another case
No symptoms or physical signs attributable to these deposits could be identified since in the group studied symptoms and signs only occurred in those individuals in whom there was other lung pathology Apparently the plaques themselves and the process responsible for producing them are symptomless
Discussion
Fibrosis The type of fibrosis found in this study was characterized as already described by a soft haziness and a finely granular or nodular appearance tending to be more marked in the lung fields and bases Dreessen apparently found a condition somewhat similar to this in his study of tremolite talc workers in the same geographical area However the fibrosis here reported was more severe than that found by Dreessen as indicated by the conspicuous presence of clinical symptoms such as dyspnea pain and fatigue in these cases and also by the more frequent appearance of granulation and fine nodulation It more closely resembled in severity the fibrosis later reported by Dreessen and Dalla among Georgia talc millers and miners Here the talc was also of the tremolite variety Analyses also failed to show the presence of free silica These authors reported 8 cases with symptoms of dyspnea cough and pain abnormal chest signs clubbed fingers and a nodular or nodular conglomerate type of fibrosis
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a nodular
DUST HAZARD IN TALC MINING
497
The occurrence of a type of fibrosis giving a nodular roentgen ap-
pearance as a result of exposure to tremolite talc dust is a matter of
considerable interest since nodular fibrosis is traditionally associated only with dust containing free silica Gardner attributed fibrosis in tremolite talc workers to the contaminating presence of free silica but inasmuch as the free silica content of the twelve samples of mineral from talc mills and mines analyzed in the present study was found to be practically negligible less than 1 per cent it seems reasonable to suppose that the fibrosis observed in these cases is primarily the result
of the inhalation of the various silicate minerals present in the dust
namely talc tremolite and anthophyllite
Microscopic study has shown that this dust is largely fibrous in character and it may well be that this particular physical characteristic
is responsible for the pathology of tremolite talc fibrosis The possibility of action analogous to that which occurs in asbestosis is suggested by several facts first the chemical and physical similarity between the minerals in this area and those found in asbestos second the fact that
the disability in tremolite talc fibrosis like that in asbestosis tends to be greater than one would expect from the severity of the lesion as
seen on roentgenological examination
Because of these similarities we have taken the opportunity to com-
pare this series of films of tremolite talc workers with those of a group
of workers showing early asbestosis They were impressed by the
resemblances in the roentgen appearances in the two groups The talc
fibrosis resembled early asbestosis in its fineness and diffuseness its hazy ground glass quality and in addition some in the series of asbestosis
films showed a mottled or nodular appearance similar to that seen in the
more advanced cases of talc fibrosis
Whatever the exact pathology may ultimately prove to be the study here reported clearly indicates from a practical standpoint that the dust encountered in the tremolite talc industry is of a definitely in-
jurious producing type which requires control in order to prevent disabling occupational disease Moreover although the number of cases here presented is small suggestive evidence has been found that
* Through the courtesy of Dr. W. J. McConnell of the Metropolitan Life Insurance Co. New York City
Mottling in asbestosis has been described by Merewether,, and also by Gardner
and Cummings. ,,
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498
*
YALE JOURNAL OF BIOLOGY AND MEDICINE
U.S.
by
exposure to tremolite talc dust is associated with increased susceptibility
protected to tuberculosis Talc plaques In regard to talc plaques one possibility to consider
is that they represent simply aggregations of actual talc dust which has
be
may remained in the periphery of the lung unable to be disposed of in any
manner This supposition makes it difficult however to account for the
presence of these deposits in a few cases only rather than in the majority
and
of those exposed
party Since talc plaques closely resemble in appearance pleural calci-
third fications resulting from traumatic pleuritis or empyema the thought
immediately suggests itself that they are in fact deposits of calcium a by The dust of tremolite talc contains tremolite being a calcium
Medicne magnesium silicate so also do other dusts such as cement and
marble Why does tremolite talc dust alone produce the opaque deposits
described of
Calcific deposits ordinarily presuppose previous irritation or injury
This fact suggests that tremolite talc dust therefore has some unique
Library
ability to irritate or injure pleural surfaces such injury being followed
National by the deposition of readily available calcium It is known for example
that the resolution of intrapleural hemorrhage is frequently followed by
calcium deposition and one is tempted to speculate as to whether the
the
needle particles present in this dust may by tissue penetration cause
of
multiple minute capillary hemorrhages whose resolution results in the
colection appearances described
The location of the deposits as seen in lateral oblique and stereo-
scopic views appears actually to be just beneath the pleural surface
the
from This suggests that they may lie in the peripheral lymphatic network
and opens up another speculative possibility In this connection an
copied
copied copied
was illustrated article by Lommel in the Deutsche medizinische Wochen- Wochen-
copied
schrift is of great interest Discussing the familiar shell appearance
occasionally seen in hilar nodes he reports in certain cases of silicosis
page large calcific deposits in the peripheral parts of the lung which to
judge by the illustrations closely resemble talc plaques His suggested
explanation is that calcium lime is laid down in inflamed fibrous
this
tissue in the congested lymph spaces which form a network around the
on
material lobules of the lung The sharply demarcated yet irregular borders of the talc plaques
The do in fact suggest that the deposit of opaque material is definitely limited
by the outlines of some irregularly shaped structure such as the walls
bility
sider 1 has any r the
ority
calci-
ught
cium and
osits
jury ique
wed
iple d by
the
ause
the
reo-
face work
an
ben-
ince
sis
sted
ous
the
les ited alls
lawlaw
Copyright
Copyright
U.S. DUST HAZARD IN TALC MINING
499 by
Gardner of lymphatic
It is of interest in this connection that
spaces and Cummings working with asbestos report marked hyperplasia
protectedmay and dilatation of lymphoid tissue in the periphery of the lung in
be
guinea which they believe may be the result of pulmonary irrita-
tion One may speculate as to whether tremolite talc may not produce
a similar condition which is then followed by the deposition of calcium
and
party in the dust
already present
is
Another interesting feature of the cases showing talc plaques is
third that radiopaque material in these cases is not apparently deposited in
the hilar nodes This suggests that talc dust does not find its way to
a
them in large amounts If this be true it would indicate a similarity in
by
this respect to asbestos which as Gardner and Cummings have shown
Medicne tends to be held in the periphery of the lungs Whatever the similarity in effect between asbestos and talc dust
however one conspicuous dissimilarity is the absence of any change
of
Library resembling talc plaques in the lungs of asbestos workers In fact as
far as we are aware with the single exception of the German reference
National given above such deposits have not heretofore been described in con-
nection with any dust
Summary
the
of
1. A study of the tremolite talc mining and milling industry in
northern New York State is reported 2. Talc in this region is of the asbestine variety mingled with
colection
tremolite and anthophyllite Analyses of material from both mines and
the
mills gave consistently a free silica content of 1 per cent or less
Microscopic from studies of dust showed the presence of fine straight needle-
copied like fibers mining
million
3. Dust counts in mining ranged from 6 to 5,000 million particles
was per cubic foot in milling from 20 to 215 million particles per cubic foot 4. In a group of 221 tremolite talc miners and millers advanced
page fibrosis was found in 32 men giving an incidence of 14.5 per cent
5. All of the cases of fibrosis occurred among those men who had
this
worked in tremolite talc for ten years or longer 107 men giving an
on
incidence for this group of 29.9 per cent
material 6. The fibrosis found in this study was of a fine diffuse type with
a roentgenographic appearance of granulation or nodulation on a hazy
background It tended to be disabling in character and was frequently
The
accompanied by dyspnea cough and fatigue
500
YALE JOURNAL OF BIOLOGY AND MEDICINE
characterized 7. There was also some evidence that this fibrosis was
by an increased susceptibility to tuberculosis Clinically significant tuberculosis was diagnosed by roentgen examination in 3 of 18 cases of
tremolite talc fibrosis where there had been no other dust exposure
8. In addition to fibrosis deposits of unidentified opaque material
in the periphery of the lungs including the region of the diaphragm and pericardium designated as talc plaques were observed in 6.3 per cent of all tremolite talc workers examined These deposits occurred independently of other lung pathology and could not be identified with any particular signs or symptoms
Conclusions
This study identified tremolite talc as a silicate dust capable like asbestos of causing a disabling pneumoconiosis It reveals distinctive pathological findings associated with exposure to tremolite talc dust which postulate a special etiology for the resulting disease There is
also evidence that tremolite talc fibrosis is associated with an increased
susceptibility to tuberculosis In the light of these findings exposure to tremolite talc dust must
be considered to constitute a definite industrial hazard requiring control of dust by suitable engineering methods
REFERENCES
1 Annual Report Chief Inspector of Factories and Workshops for England and Wales His Majesty's Stat Off London 1933 p 63 Merewether 1934 p 65
Dreessen 66-78 Merewether .
technic for deliberate production of pleural
2 Bethune N Pleural poudrage new
Thoracic Surg 1935 4 251-61
adhesions as preliminary to lobectomy J.
3 .: Effects of certain silicate dusts on the lung J. Indust Hyg 1933
4 Drees1s5en W6.6-7C8 . and J. M. Dalla Effects of exposure to dust in two Georgia talc mills and mines Pub Health Rep 1935 50 131-43
5 Fienberg R Talcum powder granuloma Arch Path 1937 24 36-42 6 Fossel M Ueber die Wirkung des Talkumstaubes im Tierexperiment Frankfurt
Ztschr f Path 1935 49 90-105 7 Fourth Saranac Laboratory Symposium on Silicosis June 19 to 23 1939
8 Gardner L. U Personal communication 1942
9 Gardner L. U. and D. E. Cummings Studies on experimental pneumonokoniosis
IV Inhalation of asbestos dust its effect upon primary tuberculosis infection
J. Indust Hyg 1931 13 65-81 97-114
10 Haynes .: Experimental dust inhalation in guinea J. Hyg 1931 31 96-123
11 Industrial Bulletin New York State Department of Labor 1938 17 1 12 International Labor Office Silicosis Proc Internat Conference held in Geneva from
August 29 to September 9 1938
13 Ladoo R. B metallic Minerals McGraw Book Co. Inc. New York 1925
Lommel .: Ueber Beurteilung und Verh^...tungder Silikose Staublungenkrankheit .
Deutsche med Wchnschr 1939 65 871-75
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The
ized ber; of
ure
rial and
in-
vith
like tive lust e is ised
trol
ales . 65 eural
933
orgia
furt
iosis
tion
123 rom 925 eit
DUST HAZARD IN TALC MINING
501
15 McCormick E. J. and T. L. Ramsey operative peritoneal granulomatous inflammation caused by magnesium silicate J. Am Med Asso 1941 116
817-21
16 Middleton E. .: Industrial pulmonary disease due to inhalation of dust with special
reference to silicosis Lancet 1936 ii 1-9 59-64
certain
17 Miller J. W. and R. R. Sayers Physiological response of peritoneal tissue to certain industrial and pure mineral dusts Pub Health Rep 1936 51 1677-89
18 Mineral Resources of the State of New York New York State Mus Bull No. 223
and No. 224. Albany New York 19 Nuck K. and W. Szczepanski Talk und Talkstaublunge Arbeitsmedicin Vol 9
J. A. Barth Leipzig 1939 20 Policard A Action des poussi^res de talc sur les poumons Arch d mal profess
1940 2 530-39 21 Schulz R. Z. and C. F. Williams Commercial talc animal and mineralogical
studies J. Indust Hyg & Toxicol 1942 24 75-79 22 St^...berK Cellular response of lymph nodes to various dust suspensions introduced
into lymphatics J. Indust Hyg 1934 16 282-95 23 Zanelli A La pneumoconiosi da talco Med del lavoro 1931 22 3-16 Quoted
by Teleky L Pneumoconiosis Supplement Occupation and Health International Labor Office Geneva 1938.
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C.-E. A. WINSLOW BIOLOGY
LUO.
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sem March, 1947
afed
NUMBER 19
MEDICINE JOURNAL
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