Document bB3OZgEManOd9wy3rgbxz6dZZ
FILE NAME Quebec Asbestos Mining Association QAMA
DATE 1952
DOC QAMA066
DOCUMENT DESCRIPTION Unpublished Conference Presentation on the Topic Pulmonary Cancer in the Asbestos Industry by Dr. Cartier at Seventh Saranac Symposium
MR CHAIRMAN ANDAND MEMBERS OF THE SYMPOSIUM
I was asked to present a paper on the topic Pulmonary :
Cancer in the Asbestos Industry not on account of any special \
qualifications but because I happen to be in charge of a Clinic
nan
which
has
as
its
primary
function
the
the
supervision
of
the
pulmonary
:
4,000 condition of some 4,000
asbestos miners such a group of employees
Jeeee
working in a small radius of 5 miles offers an exceptional oppor-
tunity to study the problem of cancer the lung in relation to
Ba
the inhalation of asbestos fibers
be
PRELIMINARY REMARKS
a
This question of pulmonary cancer among the asbestos
workers is as confusing and obscure as the etiology and the patho-
genicity of cancer in general From 1920- 1950 themedical liter- =
ature reports a series of 58 cases of pulmonary cancer and asbestosi
nevertheless Obviously this list must be incomplete but
one could
ask is it sound to think that the mere fact of detecting a total
of 58 cases of pulmonary cancer during a period of 30 years is sufficient to establish a causal relationship when one realizes that in 1950 an estimated number of 45,000 men were employed in
the asbestos industry
100,00010,00100,000 employees have
and that during that period a minimum of
inhaled a significant amount of asbestos -
just
in the
Annual
It is recognized that the English statistics published
fait Report of the Chief Inspector of Factories for the
setae
oe
-
et
~
men .
ae
Confier
Symposium
epee
te
+
_
year 1947 seem to indicate a causal relationship between the
factor asbestos and pulmonary cancer but on the other hand in
South Africa with about the same numbeorf asbestos workers as
in Great Britain and when there is also a large number of
autopsies and good medical control of all employees in dusty
trades the statistics not indicate any abnormal incidence of
'
pulmonary cancer
If the frequency of pulmonary cancer in South Africa
oo
and in the Province of Quebec is really not higher amongst the
asbestos workers than in any comparable groups as it seems to be is it possible to suspect that the asbestos mining industry might
be different from the Asbestos Textile Industrays far as carcino-
genic activity of the asbestos is concerned The fact that the
frequency among the 30,000 asbestos workers of the United States
who are also working in the Asbestos Textile Industry is not known
to be higher adds still more to the confusion
Why is the standardized death rate from cancer of the
lungs in Great Britain 3 times higher than that in the United
States - 231 in comparison to 723 rates per million
to this
It list
would indeed be very informative to have some answer|s
of unanswered questions before being able to form an
opinion and it might be that a few answers could influence or
modify any conclusion concerning a causal relationship
7
WMeeme nto
with with the treating physician the nature of any respiratory
follow episode to have
~
reports on any suspicious cases and
tT to collect additional details on the cause of the deaths
.
In summary this study is based on the results and
findings obtained from the analysis of the medical files of 3,057
employees having worked in the asbestos industry from 2 - 60
years on the findings from 53 necropsies on the details collected
espes from the death certificates on the follow reports of cases
sent to specialized centers for more complete investigation and
whem
diagnosis
It is possible and more than likely that cases of
pulmonary cancer have been missed nevertheless we think that
we have employed a standard procedure in this investigation and
that the results therefore are of sufficient interest to make
this publication worthwhile
RESULTS
Before submitting the results of this investigation it would seem proper to give a few routine tables in order to reach a better understanding of this communication
a
epre,
ce
2
er
ce
e
\
e
ee
}
.
i AGE GROUPS
'
Number of
| Employees
;
"
.
TABLE 1
FOPULATION SAMPLED
.
$
Age group distribution of 3,957 asbestos workers
=a
e
15-19 15-19 15-19 | 20 - 29 | 39
40 49 50 59 | 60 - 69 70 & Over
:
-
'
'
,
*
ee
/
76 76
1113 1113
7 1091 1091
766
50505 5
307
99
|
ae
:
35
n
,
This table
sampled population and needs
gives the age group distribution of the
.
no comment except to mention that the
average age of the asbestos workers is somewhat higher than that
of the average industrial worker i.e. 35 in comparison to
33 for most other industrial groups This remark is logical
when we know that the labor turnover in the Quebec Asbestos
Mining Industry is about the lowest of all the industries in
the whole of Canada This first table also shows that some
2,000 asbestos workers are 35 years of age and over - a representative group for the study of a cancer problem
es
of
/
,
Years in the
Industry
TABLE 2
. Years employed in the asbestos industry by 3,857 asbestos workers
2 - 4.9
+
5 - 9.9 10 > 14.9
15 - 19.9
20- 24.9
25- 34.9
ie 35 & Over
Number of
Employees
Hen - Years
640 1920
1060
645
7420
7740
476 8092
281
546
6182
14742
309
oe
12360 of:
REMARKS
2,257
men have
spent
10
years
and
over
in
the
asbestos
,
industry
,?
The second table indicates the number of years spent
in the asbestos mining industry by the 3,957 employees studied
Of course this table is not as significant as one indicating
the specific exposure for each employee by categories but after
denominator many attempts it has seemed impossible to find find a common
_
which would permit to add together the years spent in different
degrees of exposure by the same employee
has in the mind of many investi-
The years exposure
| gators no great meaning in general but in this case the fact that
56,456 years asbestos exposure having given rise to only 10
not confirmed cases of pulmonary cancer might indicate that we are
facing an acute problem
3
classification The following table 3 shows
of various
ORIN
: exposures in the asbestos mining industry I realize that such {Oy
a classification could be discussed at length and possibly
gt
RES
m emse
vec
other dusty industries it is impossible to translate with a
strict mathematical precision the different concentrations of
f t .
dust particular each job This classification is given not-
withstanding its limitations because it is based on dust
-
performed by different competent agencies and moreover
counts
because
we feel that a satisfactory classification is very useful in under-
standing more clearly scientific and medico problems
o
TABLE 3
Classification of various
ces
exposure in the asbestos mining industry
he
Estimated
degree of
hazard 0 1
2
Industrial Operations
,
ATHOSPHERIC ATHOSPHERIC Total dust count
L..P.P.C.F of air
sampled
CONDITIONS
Fercent -:
fiber count
Ste
Open Pit Shops
*
Less than 1
Open Pit Box Loader Cobber Dump
Primary Crusher
,
Dryer
Concentrating Underground all jobs under wet condition Short exposure of skilled employees
ca co co os in
3 6
Open Pit dry drilling
Secondary Crushing
.
Storage Bin
2
.
10 - 12
10 - 14
Less than 2
Less then pe
Less than 2|
5
i
6
7
5
:
:
1
:
200 200 200
3
'
~
5 ,
Underground dry drilling
Grizzlies
Shed Cobbing
Shipping Shed Cleaners Pilers
Mill Millwrights Oilers Sweepers
Testers
Bagging Department
.
10 - 15 5 - 15 534 5 534 15
10 - 25 8
20 - 30
1-3
2 14-16 14-16 10 - 14
25= g
*
20
:
28
a
wet ot
i
7
wt,
1010 My,
"
"
~,
Boe
Det
This table indicates that the total dust count and the
tenla " percent fiber count are both constituents of the degree of hazard
that a rather low total dust count may become a risk when
be
meaning
the percentages of fibers is high and inversely that a high total
pulmonary producing dust count may also become harmless in
fibrosis *
:
if the fiber percent count is low
The percentage of fibers in relation to the total count
is calculated for fibers 5 microns and over and on the principle i
that only particules having a length at least twice its width are
|
fibers As you may see in the table the industrial operations Oe
are grouped in 6 different categories and these categories are
again divided by a double line in two main groups The upper
group includes the jobs which in our experience do not produce
fibrosis of some clinical importance and the lower group the jobs
which can produce asbestosis
em
Z
There is an obvious explanation why the men working in
f the open pit do not develop asbestosis and also why the men work-
ing as baggers might develop asbestosis but it is more difficult
to explain why some industrial operations with about the same dust |
concentration as secondary crushing storage bin on one part the
grizzlies and shed cobbing on the other part have been classifi. ed
in different categories We admit that in adopting such a classification we have been influenced by our clinical findings
to
categor some extent but also by the fact that in the operations of n
3 the fiber concentration is more
than in the operations of category
constant and 2 There is
work much heavier
a marked difference
a
Oe
in the degree of hazard of categories 1,2 and 4 and 5 out the
difference is not so marked for the categories 2 and 3 This
table is important in order to fully understand those to follow
It is true that the main purpose of this presentation
is to report the incidence of pulmonary cancer in group of
3,957 asbestos workers but the nude statement that 10 cases pulmonary cancer have been detected would not be significant
of Oe
- unless ss
we can compare this prevalence with that in comparable groups
eres
gem
This task of finding a good comparable group or a
ugetpe
so
control group in this study as in any similar studies is very
es
difficult We wish it had been possible to find a control group
: in other industries or in other industrial centers in the Province :
of Quebec or elsewhere in Canada We soon industries were interested in that problem
realized that no
of cancer of the
other
lungs
nor did they have the necessary data for comparison No other
populatio male industrial city has ever had thirds of its a
adult
~ of the same age group so closely medically supervised with a
| clinical and routine roentgenographic examination as has been done :
in Thetford Mines for the last 7 years The mass surveys in
different cities did not help the situation the findings were
toc dificient doubtless because a too small proportion in the
year and over age group is taking advantage of mass survey |.
1950 As a matter of fact a mass survey in Thetford Mines in
by
we
the Provincial Department of Health did not detect a single case
of pulmonary cancer as in most of the other centers and the analys
of the results is not very helpful
:Say
It seems probable that the general increase in the
frequency of lung cancer
observien many cities a
is not sudden
purely apparent but when
and important increase in
we
the
lung cancer mortality rates such as the increase the City
of Montreal from 7.7 in 1946 to 12.9 in 1949 we must admit
oo
that the medical diagnosis facilities are responsible to an
appreciable extent for such an increase Therefore the exclusive e
analysis of death certificates in various centers which do not
has have the same medical facilities to be used with caution
_
:
not should it be used unless the facilities are comparable
In this study the comparative statistical analysis of the death
certificates was not used because in the opinion of the official
statistician
the National
of the
Cancer
City of Montreal and Institute of Canada
of the Statistician of
the death certificates
of |
the asbestos group consisted of a highly selective group and a
similar selective group was not available elsewhere
For all the reasons mentioned above and the fact of
being unable to make a better selection we decided to compare the |
incidence of pulmonary cancer in different groups of asbestos
workers who have been submitted to the same medical investigation
and who at the same time were presenting enough characteristics
Lt
eH
to permit certain conclusions or imprkssions
ge
mere
eae
amme
be
TABLE 4
Incidence of pulmonary cancer
according to degree and length of exposure by age groups
GROUP 1
Unsignificant exposure
AGE GROUPS
16 - 39
40 - 86
'
.
GROUP 2
Significant exposure
|
AGE GROUPS
16 - 39
| 40 - 86
".
z..
Number of
Employees
Prevalence of Pulmonary
Cancer
.
2229
1367
56
305
.e)
6 0.44
--
,
,
7
4 1.32 .
:
REMARES
Undignificant
and less than
exposure 15 years
includes 3-4-5
men with
exposure
0-1-2
Significant exposure includes only men with more than 15 years 3-4-5 See Table 3
the
The usual calculations of the standard error
observed difference in percentages of incidence in
show that
the 2
groups
.
.87 is inferior to twice the
This table shows that there
Standard Error 1.346
is no statistical evidence
incidence ~
that the
of pulmonary cancer in the group 2 including
exposure the employees who have sustained severe
and all those
developed have also
asbestosis is higher than in group 1 of
who
those without significant exposure and without any employees
clinical asbestosis
pron
teh
-12-
me.
Tre
recognized It is
that this table might lose a large
enactatte part of its meaning if it is shown that any intensity of
a
asbestos inhalation or any amount of asbestotic fibrosis could
be considered as cancerigenic because then a large number of
will employees in group 1
be transferred to group 2 and it is
that probable
an unknown number of
cancers in the
pulmonary group 1 would also have to be transported to group 2 changing eens
rapidly the observed difference in incidence as well the
conclusion
As a logical complement to this table we wish we
could give a long series of other tables showing the incidence
recent of pulmonary cancer in groups with or
yreeamroste in groups with gradual exposure of 1-2 to 15
exposure
or a similar
in exposure of long duration 15 years and over also groups
with extensive exposure and asbestosis or without asbestosis
The data obtained from such tables might tell us in
the hypothesis of a
of asbestos dust is
causal relationship more important than
whether the inhalation
the presence of
asbestosis itself also what approximative degree of asbestos
inhalation can be considered as predisposing to cancer
ge
te
.
.r0s,
me
wer
IES
TABLE 5
Comparative Incidence of Pulmonary
Cancer in 2 groups of 53 Autopsied asbestos workers
t
;
Kumber
Autopsied
Number of
Fulmonary
Cancer
Fercent in
Each Group
GROUP 1
Employees with
Asbestosis
34
4
11.7
GROUP 2
Employees without
Asbestosis
TOTAL
19
53
6
10
31.57
31.57
This table shows the prevalence of pulmonary cancer
in a series of 53 autopsied asbestos workers having worked in
the asbestos mining industry from 17 to 40 years in different
degrees of exposure
This series of autorsies is not as important as the
series published in the Annual Report of
s
year 1947 but can be considered as less
Great Britain
selective and
for the
more
representative in not being composed from cases of asbestosis
exclusively but composed of all the employees who happen to be
autopsied although it should be mentioned that there was an
e.
gore
ie
a
. -14-
eal
Fee
RaSERnNOtK
involuntary selection in the sense that most of these employees
have been autopsied because they were presenting some respiratory
symptoms . ;
e
This coincidental selection might explain to some
.
extent the high percentage of cases of asbestosis but in many
instances the amount of asbestotic fibrosis detected was described 22
*
as minimal and of no clinical impimportance ortance because not sufficient
to produce symptoms
Because the observed difference in percentages of
incidence is inferior to twice the Standard Error this table
does not reveal a statistical evidence of a causal relationship between asbestosis and pulmonary cancer
Unless we have the opportunity to perform an autopsy on all employee's who die it remains difficult to explain why in our series there are less cases of pulmonary cancer in the
asbestotic group and I think we have here a good illustration
as to why many statisticians counsel not to draw any conclusions
from statistics based on a selective group even if such a group
ns
be in the
autopsy
by
category because the role played by the factor
incidence might be too great
ee me ee
otek
TABLE 6
Deaths from Pulmonary Cancer as a
of deaths from Cancer of all
1940 - 1950
proportion
sites
Number of Cancer All forms
Province of Quebec
ity of Montreal ity of Quebec
ity of Thetford
Mines .
43643 15247
2543 172
.
Number of
Pulmonary Cencer
1393 918 94 g
Percentages
Percentages
3.2
6.0
3.7
5.2
,
Table 6 was prepared for the purpose of determining if'
the ratio between the number of cancer deaths all sites and the
pulmonary cancer deaths was somewhat different in Thetford Mines
from the ratio observed in few other control groups First it
- should be mentioned that about 90 of the cases of of pulmonary
Thetford
cancer in Montreal and 100 of the cases of the Thetford Thetford Group
are autopsy cases and both cities have thoracic clinics clinics clinicsclinics clinics so
these two groups are reasonably comparable In Quebec City for the specific period 1045 - 1950 inclusive % of all cancer deaths were also pulmonary cancer It was thought that had a special factor existed in Thetford Mines the ratio between the number of total cancer and the number of pulmonary cancer
would have been different The difference observed here is
not sufficient to draw any conclusion either positively or
negatively
Sh
;
TABLE 7
Comperative 10 Years Expectancy and 10 Years Prevalence of Pulmonary Cancer in 2 cities
PLACE
YEARS
| Thetford Hines .
' . ry
i; Montreal
1941 - 1950 1941 ~ 1950
10 YEARS
EXPECTANCY
10.5
- 693
10 YEARS PREVALENCE
9
856
ES
Based on U.S. Public Health
population of 48,833 giving ancy of 7 cases per 100,000
Service Report 2537. A a year pulmonary cancer population
rendom
expect-
Table 7 was prepared at the suggestion of Dr. Philipps
Statistician for the National Cancer Institute of Canada who
thinks that the comparative study of the 10 years expectancy and _
:
10 years actual prevalence of pulmonary cancer in Thetford Mines
and in Montreal will be more informative and more conclusive
than analysis of the mortality rates According to the surfey of Dr. Dorn taking random population of 48,833 an annual inci-
dence of pulmonary cancer of 7 cases per 100,000 can be expected
giving a year expectancy of 7. It is true that Dr. Dorn's survey
was made in 1943-45 and that the year expectancy might have
~ increased recently As a matter of fact Watson of Saskatoon Canada found in 1948 a year expectancy of 8.5 therefore a year expectancy of 7 is a rather conservative standard to On that basis Thetford Mines with an average population -
of 15,000 for 1940 - 1950 perioids supposed to have 10.5 cases
8,
ee
es
sovmepr
IS
of pulmonary cancer and the actual prevalence is 9 cases
Again Again it seems logical to think that the 10 year prevalence for
EPO0
Fk pulmonary cancer in Thetford Mines where thirds of its adult
population is working in the asbestos industry
<
than the normal 10 year expectancy should the
would be higher
factor asbestosis
be considered carcinogenic
.
SUMMARY
'
ee eae
The etiology and the pathogenicity of the pulmonary cancer in relation to asbestos factor is as obscure and confusing
.
as those of cancer in general , and in presence of contradictory presence
data the many different aspects of the problem should be considere~ before arriving at a conclusion
The purpose of this study is to learn the incidence of pulmonary cancer amongst the 3,957 asbestos mining workers and to compare this incidence with other comparable groups This incomplete epidemiological report is a contribution to a more complete investigation under progress at the Saranac Laboratory
According to the standard procedure the medical files the results of medical supervision the annual stereograms of all the asbestos workers having worked from 2 to 60 years and the findings of 53 autopsies have been used as material
The results have been tabulated and compared to control groups and we think that the data collected in the Asbestos Mining Industry are not exactly superposable to the results found in the
...
\
.
.
..
-15-
English Asbestos Textile Industry of Great Britain and if
do not permit to deny a causal
they
relationship between the inhalation :
of
asbestos
dust
and
the
occurence
of
pulmonary
cancer
they
do
not seem either to bring any positive evidence
:
me
ee
Oe FOO
Discussion
KHOADS
was interested in Dr. Cartier's
remark that the mass
reveal
survey
employed inhis his group did not reveal
any patients with early pulmonary concer
I presume that the mass
survey was not
sufficiently large and therefore therefore this
method of revealing a disease which is
treatable and often
curable
curable curable may not
have been adequate
a
In regard to the 53 autopsied
individuals of whom 10 had
I presume they were autopsied because it
was thought that they
pulmonary cancer
Those
Those were not ro atine atopsies
\: pulmonary cancer cancer
may have had
inference 20. RHOADS The implication is clear that there is no danger
cancer to workers in this
particular group
Perhaps that
It appears to me that asbestosis is
a very healthy ailment as
from palmonary
inference is true far as cancer
is concerned
:
} )
"
Cariter UNIDENTIFIED SPEAKER Dr.
signs trouble what are the first
of
or
signs
of
trouble
from |
exposure to asbestos
ee
he
<
a
es
e
not H
DR CARTIER I do
believe there
are any specific symptoms If the fibro-
Noi
sis is extensive enoughthere is dyspuce dyspuce and
cyanosis sometimes to an extreme
degree have had
In our group we have marked exposure to
had 99 cases of asbestosis asbestos for years and many
These individuals
of themthem on reaching
age 50 to 55 are more dyspnsic and @seen to die more rapidly without much
disease They go downhill rapidly withwin ithin a few months
DR ROADS Of what do they die
.
DR CARTIER
Some
miscellaneous from cardiac disease and fri
miscellaneous
miscellaneous
experience diseases some from bronchiectasis In my
there is
except that they fail rapidly rapidly - in two orthree months
.
generalized generalized generalized
no special picture
ER the
VORWALD
We have been
encouraging Dr. Cartier
rather isolated population of Thetford and we
to continue this
are conducting a
study of
similar
epidemiological sursvey urvey of a neighboring neighboring community which is also engaged in the
mining mining and processing of asbestos We suggested
deter are
the
incidence
incidence
of
of
cancer
cancer
cancer
in
his
in his
exposed
exposed
to Ir Cartier that ne migat migat
by group
group in TThetfhord etford
by
review-
review-
that method
We have considered
sputum examinations but at present the best
ve cu^-de ict ict study the quest roentgenograms of this this erge series of indivi
.
Cuals exposed in a special industry
DR RICADS
Lid you discover
any cancer cases
in
doing
so doing
.
survey DR CALTIFE Yes with the ray No
cases were revealed by the mess
all the cases were detected in the clinic
ast bax 4
ER MAGADS You say that the mass survey did not reveal these cases tot
that the roentgenograms taken when the individuals applied applied forfor for medical care did
DR CARTIER No the roentgenogram was taken duringa routine examination
at the clinic
e
DR PHOADS How does that differ from the is survey 4
IR CARTIER
It differs in that
:
people over people
50
years
years
of
ag age e
do
not
tane
advantage of the mass survey All the cases nave been detected at the clinic
and later have been followed up and have come to autopsy
ae
7
i
cod
DR INCAIS It appears that somehow the mass survey doesn't always result in the actual detection of cancer and in the bringing of the patient into
Sars
ove