Document 6bdaDoLak57rKRrZ8wKOKqKrR
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Asbestos Bodies in Human Lungs at Autopsy
Dzidra Cauna, MD, Robert S. Totten, MD, and Paul Gross, M D
371
The incidence of asbestos bodies in the lungs was in products such as asbestos roofing, roof tiles, ceil
vestigated in 100 autopsies of adults. Lung smears were ings, floor tiles, pipe and electrical insulation, car
taken from the sectioned surfaces of the upper and lower brake linings, cement, etc. Since asbestos is vir
lobes of both lungs. The slides were dried and mounted tually indestructible they predicted that the
without staining, and approximately 400 low-power fields amount of air-borne asbestos fibers in cities would
were examined in each slide. Routine histological sections increase in the future and become a contaminant of
of unexpanded lungs were also examined in all cases. As the air. They further suggested that the results of
bestos bodies were found in 4 1 % of the subjects. They life-long inhalation of these fibers might lead to
were not encountered in persons up to 24 years of age. almost universal basal asbestosis in adults, and a
Among males the incidence was 4 7 % , and in females frequency of mesothelioma of pleura or peritoneum
3 4 % . Although significant microscopic pulmonary fibrosis higher than that of bronchial carcinoma today. As
was encountered in two positive cases, no instance of bestos has also been implicated as a possible factor
classical asbestosis was found. Mesothelioma of the pleura was not encountered. Primary lung carcinoma oc
See also page 419.
curred in one patient with asbestos bodies and in one in the development of carcinoma of the lung.4
without.
According to Doll5 the risk of developing a lung
cancer is increased among asbestos workers, but
W agner and associates1 reported on the occur rence of diffuse pleural mesothelioma in per
this is denied by others.6,7 As the United States accounts for roughly over
sons from a large asbestos mining area in tohnee third of the world's consumption of asbestos,
northwest of Cape Province, South Africa. Since Thomson6 initiated an investigation of the fre
mesothelioma of the pleura was regarded as an un quency of asbestos bodies in lungs in Miami, Fla,
common tumor, and was rarely seen elsewhere in where even higher positive figures were obtained
South Africa, they undertook an investigation of than in Cape Town.
these cases. In ten cases, lung tissues were available
Pittsburgh and its environs are free of asbestos
for microscopic examination and asbestosis was mines, but it is a large industrial center with an
found in eight.
. expanding modem building program. The purpose
Thomson2 reported seven cases of mesothelioma, of this investigation was to obtain preliminary
four in the pleura and three in the adjacent perito data on the incidence of asbestos bodies in the neum, encountered over a period of three years in lungs of patients who died at Presbyterian-Univer-
the autopsy service of one teaching hospital, in sity Hospital.
Cape Town. In all seven cases the microscopic pic ture was that of pulmonary asbestosis, with abun
Material and Methods
dant asbestos bodies and fibrosis in the basal por
The work was carried out in the Presbyterian-
tions of the lower lobes. Since only one of these seven patients had a history of occupational ex posure to asbestos, Thomson and his associates3 undertook an investigation on the frequency of
University Hospital, which receives patients main ly from the city of Pittsburgh and the surrounding area. The material consisted of 100 routine autopsy
asbestos bodies in the lungs in general population
of Cape Town in routine autopsies. Of 500 cases
examined, 132 were positive for asbestos bodies.
These results suggested that asbestos was becom
ing a modem urban hazard. According to Thomson
et al,3 world consumption of this mineral had in
creased from 300,000 tens in 1934 to 2,400,000 tons
in 1961. It is used in a wide variety of industrial
From the departm ents of pathology. P resbyterian-U niversity H o s p ita l a n d U n iv e r s ity of P itts b u r g h S chool of M e d ic in e <D rs. C auna and T o tte n ), and In dustrial H ygiene F oundation, Inc., M ellon In stitu te (D r. G ross), Pittsburgh.
K eprint requests to 230 L othrup St, P ittsburgh 15213 (D r. C auna).
1. Incidence of positive cases relative to age groups.
JAMA M a v 3. IQfi S Vnl 1QP Nn S
111
372 ASBESTOS BODIES--CAUNA ET AL
Age 15-24 25-34 35-44 45-54 55-64 65-74 Over 74
Total
%
Table 1.--Distribution of Asbestos Bodies in Lung Smears According to Age and Sex
M ales
Fem ales
Both Sexes
Positive
4 3 2 9 3 4
N egative 6 1 6 1 6 5 3
Total 6 5 9 3
15 8 '7
Positive
1 3 1 4 5 2
N eg ativ e 3
1 4 5 7 11
Total 3 1 4 5 9
12 13
Positive
5 6 3 13 8 6
N eg ativ e 9 1 7 5
11 12 14
v 25 47%
28 53%
53 100%
16 34%
31 66%
47 100%
41 41%
59 59%
Total 9 6
13 8
24 20 20
100 100%
cases, 53 men and 47 women, ranging in age from 17 to 91 years. Twelve subjects were Negroes. The occupation of the women was given as housewife in most cases, those of the men ranged from manual workers to executives. In no case was any connec tion established with manufacture of asbestos prod ucts, although the occupations were taken from the charts, and neither the patients nor their families were questioned directly. The presence of the as bestos bodies was determined by the use of lung smears3 taken from the upper and lower lobes of both lungs (four slides from each case). The smears were obtained by an incision into the lung tissue from which a small quantity of blood or edematous . fluid was expressed onto a glas slide and spread evenly over an area approximately 12 sq cm. The slides were air-dried and mounted without staining. In each slide approximately 400 low-power ( 16-mm objective) fields were examined, and the total num ber of asbestos bodies was registered. Some smears were stained for iron (Pearls reaction) which colored the iron-containing protein globules blue. Routine histological sections of unexpanded lungs stained with hematoxylin and eosin were also ex amined in all cases.
Results
The problem of absolute identification of asbes tos in asbestos bodies is a difficult one, and to our knowledge no successful histochemical procedure has been devised. Chemical examination of lung tissues for acid insoluble residues yields a value for total silica that might represent asbestos or other silicates. No chemical determinations were done in these cases. An attempt was made to identify the element silicon in asbestos bodies (from a known case of asbestosis) by electron probe analysis. Al though iron was readily identified, no silicon was encountered.0 The bodies seen in talcosis are identi cal to those in asbestosis and are thought to be the result of contamination with tremolite, another fibrous silicate. It is possible that the bodies seen in our material are associated with tremolite. With the above limitations in mind, the term asbestos body is used here to mean the typical segmented, iron-en crusted structure known to be associated with clini cal and experimental asbestosis.
Asbestos bodies were found in 41 of the 100 sub jects. The incidence of positive cases was higher in men, 47%, than in women, 34%. Up to the age
of 24 years (six persons) no asbestos bodies we encountered. These data are summarized in Tab 1. Considering the age groups separately, the higl est relative incidence of positive cases was four between 25 to 34 years as compared with any otb age group (Fig 1). Since these are all relative small groups the significance of the differences doubtful.
Positive cases were more frequent among mat ual workers than among professional and admini trative occupations. The number of Negro subjec was only 12, but in seven subjects asbestos bodi< were encountered.
In the majority of the positive cases, one to tc asbestos bodies were found (Table 2). The max mum number of 473 was counted in a male subjec aged 63 years, whose occupation was a sales eng neer for a pump company. However, no particuli importance can be attached to the actual frequenc of the asbestos bodies encountered in each ca; because the concentration of the bodies depends c the site from which the smear is taken and on tl amount of edema and congestion in the lung at tl time of death.3 In this investigation samples wei not taken specifically from the basal portions < each lobe, where the number has been reported 1 be highest, but from random sites.
In the lung smears, asbestos bodies were readil recognized, because of their typical orange-brow color and segmented appearance (Fig 2). The were often partly enclosed by macrophages. On! those cases with typical bodies such as seen in F: 2 were accepted as positive. In some positive an some negative cases, atypical elongated structuri were seen, but these were not considered as asbestc bodies. In 24 positive cases, some macrophag*
Table 2.--Number of Asbestos Bodies Found in Positive Cases*
No. of A sb esto s
B o d ies 1
2-10 11-20
29
36
41
51 473
M ates 7
14 1 1
.
1 1
Fem ales 6 6 2
1 1
Totai
25 16
*1,600 low pow er fields ex am ined in each case.
Total 13 20 3 1 1 1 1 1
41
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2. Asbestos body intimately related to a macrophage. Unstained lung smear of 65-year-old white scrap-iron dealer (x l,7 3 6 ).
contained coarse orange-brown granules, which also gave a positive iron reaction. Macrophages with these coarse iron-containing granules were also found in smears of six negative cases.
In histological sections of lung tissues asbestos bodies were found in only four positive cases, all among the higher counts. These bodies were situ ated within the lumina of alveoli and were usually partly enclosed by macrophages as in the smears (Fig 3). Interstitial fibrosis of some significance was observed in only three cases, two of them with asbestos bodies (three and four respectively) in the lung smears, and very few macrophages with coarse granules. In the third case with fibrosis, as bestos bodies were not found, but macrophages with coarse brown granules were seen in smears and his tological sections. No case of classical asbestosis was found and mesothelioma of pleura was not encountered. Primary lung carcinoma occurred in one case with asbestos bodies and one without.
The fate of asbestos bodies in the lung is as yet not known. According to Knox and Beattie,10 and Holt et al,11 the bodies disintegrate after a period of time producing a large number of fragments which are collected in phagocytes. In our material, macrophages frequently contained coarse brown granules in asbestos positive and also in some nega tive cases. These granules gave a positive iron re
L -- J
3. Asbestos body intimately related to a macrophage inside an alveolus. Stained lung section of 57-year-old unemployed white male (x l,7 3 6 ).
action, and judging by their size, they could consti tute fragments of disintegrating asbestos bodies. However, since demonstration of iron in the coarse granules is not a positive identification of fragments of asbestos bodies, the question cannot be settled.
On the basis of their experiments with rats, Holt et al,11 suggested that fibrosis of the human lung was not caused by asbestos bodies, but by small asbestos particles, derived from the break-down of these bodies. In our limited material no correlation between the presence of asbestos bodies or macro phages with coarse brown granules and pulmonary fibrosis was determined.
The overall incidence in this Pittsburgh series of 41% asbestos positive cases substantially exceeds that of Cape Town with 26.4 %123456and Miami" with 27.9%, the only two localities where this type of information is available for comparison so far. This may merely represent a difference in technique among the three groups or perhaps reflect a real difference in atmospheric pollution among the three cities. In any event the figures from these three widely separated urban communities indicate that asbestos bodies are commonly encountered in hu man lungs. It is suggested therefore that studies of this modern air contaminant should be extended.
T his investigation w as supported in p art by Public H ealth Service grant HE-06675.
References
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*
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'
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-
10. K nox, J .F ., an d B e attie, J .: D istrib u tio n of M ineral P a rti cles a n d F ib ers in the L ung A fter E xposure to A sbestos Dust, A rc h In d u st H y g 10:30-36 (J u ly ) 1954.
11. H olt, P .F .; M ills, J.; and Y oung, D .K .: E arly Effects of C h ry so tile A sbestos D u st o n R a t L ung, J P a th B a d 87:15-23 ( J a n ) 1964.
JAMA, May 3, 1965 Vol 192, No 5
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