Mesothelioma in Italy
Unusually High Incidence of Malignant Pleural Mesothelioma in a Town of Eastern Sicily: An Epidemiological and Environmental Study.
In a recent epidemiological study, researchers investigated mortality from malignant pleural neoplasms in Italy, and they detected some geographic clusters of cases of this disease. We found a town located in a volcanic area of eastern Sicily to be of special interest. The residents, some of whom were diagnosed with pleural mesothelioma, had never had any relevant exposure to asbestos during their professional lives. The results of an environmental survey suggested that a possible cause of asbestos exposure was the stone quarries near the town. The products of the quarries contain fibrous amphiboles, which are used widely in the local building industry. These fibrous amphiboles were identified as intermediate phases between tremolite and actinolite. Samples were collected from buildings in the town, and concentrations of amphibole fibers were evaluated. Fibrous phases were detected in 71% of the samples, and fiber concentrations ranged from a few thousand to more than 4 x [10.sup.4] fibers/mg of material. In addition, we conducted a study on the mineral fiber lung burden in a pleural mesothelioma case. Many mineral fibers that were classified as the same tremolite-actinolite fibrous amphibole found in the quarries and in the building materials were detected in the lung tissue. The results suggest that the inhabitants of the town we studied had been exposed for several decades to asbestos fibers that were present in the material extracted from the local stone quarries. The material was subsequently used in the building industry, and this has caused an increased risk of pleural mesothelioma in the area.
THE CAUSAL ASSOCIATION between malignant mesothelioma and exposure to asbestos fibers dates back to the early 1960s. This specific neoplastic form, generally localized in the pleura, is a rare tumor, the incidence of which is estimated at 1-2/million persons [multiplied by] y in the general population.[1] Pleural mesothelioma can be caused by occupational, domestic, or residential asbestos exposure; the etiologic role of other factors is negligible.[2]
In a recent epidemiological study on mortality for malignant pleural neoplasms in Italy, Di Paola et al.[3] detected some geographic clusters of cases. For some of the cases, previous asbestos exposure was easily identifiable, whereas for others an occupational exposure could not be suggested.
Given the preceding facts, we found Biancavilla, a town in eastern Sicily located in a volcanic area, to be of special interest. Industrial activities involving asbestos have never occurred in Biancavilla. The subjects who resided in this town--and for whom a diagnosis of pleural mesothelioma had been made--never had any relevant exposure to asbestos during their professional lives.
The results of an environmental survey, which was conducted by the Istituto Superiore di Sanita in collaboration with the local health authorities, suggested that a possible cause of the asbestos exposure of Biancavilla's population was the stone quarries located in Monte Calvario. Monte Calvario is located on the southwest side of the Etnean volcanic complex, northeast of Biancavilla. The materials extracted from the quarries contain large quantities of fibrous amphiboles; these materials are used widely in the local building industry. In consideration of the available data and in view of some analogies with other situations observed in various areas of the Mediterranean basin,[4-8] we undertook an in-depth study of the potential connection between the increased occurrence of pleural mesothelioma and the presence of mineral fibers in the building materials that originated in the stone quarries.
I. Mortality and Morbidity among Residents
I. Material and Method
We studied cause-specific mortality among residents in Biancavilla from 1980 (i.e., the first year for which such figures were available at the municipality level) through 1993 (i.e., the most recent year for which mortality data were provided by the National Institute for Statistics. We selected causes of death for which a causal association with asbestos has been ascertained (e.g., malignant neoplasms of the pleura, peritoneum, and lung) or suspected (e.g., malignant neoplasms of the ovary).
We are aware that the relationship between ovarian cancer and asbestos exposure is controversial. The results of epidemiological and experimental studies indicate a possible association between, ovarian cancer and materials of the talc-asbestos group.[9] Findings relative to gas-mask assemblers in the United Kingdom support this hypothesis,[10 11] and, recently, in two Italian studies researchers reported an increased risk of ovarian cancer in female workers exposed to asbestos.[12 13] In our view, the aforementioned evidence justified the inclusion of ovarian cancer in the mortality study.
For each cause of death, we confronted the observed morality with the corresponding expected value on the basis of cause-sex-age-calendar year-specific morality rates of Sicily's population. To this end, we used the epidemiological databank of the National Board for Energy, New Technology and Environment. Standardized mortality ratios (SMRs) were computed, and we estimated their 95% confidence intervals (CIs) in accordance with Poisson distribution.
Cases of pleural mesothelioma were searched thoroughly via the files of Biancavilla Registrar Office and hospital discharge cards. Patients or their close relatives were interviewed about previous fiber exposure, and we used guidelines of the National Registry of Mesotheliomas[14] to assign them to exposure categories.
I. Results
Mortality. A significant increase in mortality from malignant pleural neoplasms occurred in Biancavilla during the study period (Table 1). The increase was relatively stronger (a) among women, (b) in subjects 65 y of age or less, and (c) during the most recent years. No comparable finding could be detected in any of the neighboring municipalities.
Table 1.--Mortality from Malignant Pleural Neoplasms in Biancavilla, 1980-1993: Analysis by Age, Class, and Calendar Year
Men
Year and age Obs. Exp. SMR 95% CI
1980-1993:
all ages 4 1.57 255 69, 652
1980-1987:
all ages 2 0.74 270 33, 976
1988-1993:
all ages 2 0.82 244 30, 881
1980-1993:
< 65 y of age 2 0.62 323 39, 1,165
1980-1993:
[is greater than or
equal to] 65 y of age 2 0.95 211 26, 761
Women
Year and age Obs. Exp. SMR 95% CI
198.0-1993:
all ages 5 0.74 676 219, 1,577
1980-1987:
all ages 2 0.40 500 61, 1,806
1988-1993:
all ages 3 0.33 909 188, 2,657
1980-1993:
< 65 y of age 3 0.27 1,111 229, 3,247
1980-1993:
[is greater than or
equal to] 65 y of age 2 0.48 417 51, 1,505
Total
Year and age Obs. Exp. SMR 95% CI
198.0-1993:
all ages 9 2.31 390 178, 740
1980-1987:
all ages 4 1.14 351 96, 898
1988-1993:
all ages 5 1.15 435 141, 1,015
1980-1993:
< 65 y of age 5 0.89 562 182, 1,311
1980-1993:
[is greater than or
equal to] 65 y of age 4 1.43 280 76, 716
Notes: Obs. = observed, Exp. = expected, SMR = standardized mortality ratio, and CI = confidence interval.
The mortality from the other causes under study appear in Table 2. The numbers of observed and expected cases of lung cancer were almost the same, and the SMR value was close to the unit. It should be noted, however, that a somewhat lower value could have been hypothesized inasmuch as Biancavilla is in a rural area. We were unable to detect any increased morality from ovarian cancer, whereas peritoneal neoplasms exceeded the expected value among women--even though statistical significance was not attained.
Table 2.--Mortality from Lung, Peritoneal, and Ovarian Neoplasms among Residents in Biancavilla, 1980-1993
Obs. Exp. SMR 95% CI
Malignant neoplasm of lung
Men 69 70.05 99 77, 125
Women 11 11.16 99 49, 176
Total 80 81.21 99 78, 123
Malignant tumor of peritoneum
Men 2 0.96 208 25, 753
Women 4 1.30 308 84, 788
Total 6 2.26 265 97, 578
Malignant ovarian neoplasms
Women 2 6.03 33 4, 120
Notes: Obs. = observed, Exp. = expected, SMR = standardized mortality ratio, and CI = confidence interval.
Morbidity. The clinical information available to us is shown in Table 3. At least one hospital record was available for 16 cases. Histologic examination was reported for 9 cases, cytology alone was performed in 3 cases, 1 case was diagnosed following cytological examination supplemented with computerized tomography, and 1 case was diagnosed in clinical examination. No evidence of diagnostic examination was available for 2 cases. Five cases were under the age of 45 y, 5 were between 46 and 65 y, and 7 were over 65 y of age.
Table 3.--Clinical Information
Case Gender Age Occupation
A 1 F 63 Housewife
B 2 M 68 Bricklayer, foundry worker,
railroad worker
C 3 M 61 Bricklayer, farmer
D 4 M 44 Bricklayer, postman
E 5 M 44 Clothing industry worker, tailor
F 6 F 62 Housewife (married to farmworker)
G 7 M 40 Printer house worker (3 mo), post
office clerk, school teacher
H 8 M 63 Farmer
I 9 M 42 Citrus fruit seller, farmworker
L 10 M 29 Farmworker
M 11 F 77 Housewife (married to farmworker)
N 12 M 68 Gas station attendant, paper
industry worker, car-body lining worker
O 13 F 86 Housewife (married to farmworker)
P 14 M 55 Maker of prefabricated units for
construction, porter
Q 15 F 70 Housewife
R 16 F 76 Nun
S 17 F 71 Housewife (married to bricklayer)
Occupational
Case Gender Age exposure Specimen
A 1 F 63
B 2 M 68 Probable Histology
C 3 M 61 Possible Histology
D 4 M 44 Possible Cytology
E 5 M 44 Possible Histology
F 6 F 62 Cytology
G 7 M 40 Possible
H 8 M 63 Histology
I 9 M 42 Histology
L 10 M 29 Cytology
M 11 F 77 Histology
N 12 M 68 Possible Histology
O 13 F 86 Histology
P 14 M 55 Probable Histology
Q 15 F 70
R 16 F 76 Cytology
S 17 F 71
Notes: F = female, and M = male.
Two subjects had participated in occupations for which asbestos exposure was probable; in 5 cases, occupational exposure to asbestos could not be ruled out. There was no evidence of occupational asbestos exposure for 9 subjects, and for 1 case we were unable to assess occupational history (this individual had lived in Biancavilla subsequent to 1996, whereas all other's had been residents for several decades).
The case series reported in Table 3 appear adequately exhaustive--at least in the most recent quinquennium. Given that 8 cases occurred during the recent 5 y in a population of approximately 23,000, we estimate the annual incidence rate to be approximately 7.0 x 100.000, which is about 10 times higher than the average incidence rate in Italy.[15]
II. Tremolitic Amphibole from Monte Calvario (Biancavilla)
The Monte Calvario area is located near the town of Biancavilla, on the southwest side of the Etnean volcanic complex (eastern Sicily). This hill, now completely removed, was, until a few years ago, more than 500-m high. It was formed by a series of aligned domes made up of autoclastes of highly viscose benmorreitic lava, which was then hydrothermally altered with considerable secondary hematite crystallization.[16]
At present, the morphology of the area appears totally changed because stone quarries for the building industry are present. The available volcanic material in the quarries had likely been submitted to a high temperature metasomatic process in the presence of vapor. The absence of water participation is demonstrated both by the chemical analyses reported[17] for the Biancavilla benmoreite lavas and by mineralogical association, which is characterized by anhydrous mineral phases (i.e., feldspars, quartz, pyroxenes, and hematite). These particular conditions hindered the crystallization of the hydrate phases to micas and zeolites--both of which are normally abundant in volcanic alkaline products.
From a mineralogic point of view, Monte Calvario is well known because there are various mineral samples present in the volcanic products in the area. There are, however, no previous data about the occurrence of fibrous, yellow and brown tremolitic amphibole, identified during a recent preliminary mineralogic investigation.[18]
II. Material and Method
The samples used for the present investigation were collected directly at the front of the quarry, where the grey-red lava shows vertical interstices filled with granular material made up primarily of altered lavic clasts. This material, which is colored whitish or grey to yellow-orange, is so light and friable that specimens crumble under finger pressure. It was in these lavic clasts that we detected the amphibole, which had a prismatic or acicular habit; it was primarily bright yellow but also contained a reddish-brown coloring. The largest amphibole crystals (i.e., [is greater than] 2 mm long) are embedded in the rock matrix, whereas the smaller acicular crystals line the hollows. In addition to the amphibole, microgranular quartz, k-feldspar, plagioclase, pyroxene, and hematite were also detected. The x-ray analysis of the two amphibole types (i.e., yellow and red-brown) was conducted by the Debye-Sherrer method for single crystals (114.59 mm, nickel filter, CuKa radiation, 40 kV, 20 mA). We studied the morphological and compositional differences of the fibrous amphibole samples with scanning electron microscopy (SEM) and with energy dispersive spectroscopy x-ray microanalysis.
II. Results.
With the x-ray investigation, we were able to identify intermediate mineralogical phases between tremolite and actinolite: [[Ca.sub.2][(Mg, Fe).sub.5][Si.sub.8][O.sub.22][(OH, F).sub.2]]. In the yellow samples, the tremolitic component (i.e., magnesium-tremolite) appeared to prevail; in the brown samples, the actinolitic component (iron-actinolite) predominated.
X-ray microanalysis (Fig. 1) revealed a moderate compositional variability between the two types of fibrous amphibole detected. The brown crystals were rich in iron, aluminum (Al), titanium, and fluorine (F); the yellow crystals had a higher presence of silicon, magnesium, and sodium (Na) than the brown crystals. The fibrous amphibole was considerably fluorine enriched--the OH groups in the tremolite structure were almost completely substituted. Both types of amphibole phases presented an unusually high content of Al, Na, and F; this fact admits their classification as Na-F-tremolite and Na-F-actinolite.
[Figure 1 ILLUSTRATION OMITTED]
The fibrous habit of the amphibole phases was usually evident only under SEM at a high magnification (i.e., [is greater than] 10,000x). The fibrous habit was clearly seen, and it corresponded with cleavage plains and fractures in crystals that appear to have macroscopic prismatic habits (Fig. 2).
[Figure 2 ILLUSTRATION OMITTED]
III. Presence of Amphibole Fibrous Phases in Building Materials Used in Biancavilla
We conducted an investigation to determine the extent to which the local building industry had used sand and other building materials contaminated by amphibole fibrous phases. The search eclipsed more than 50 y of production in the Monte Calvario quarties. Specifically, we attempted to determine (a) the material under which the materials from Monte Calvario were used (i.e., sand, rubble, and other); (b) percentage of buildings in which the materials were used; (c) period during which the buildings were constructed or restructured; and (d) type of materials and their destinations.
III. Material and Method
We collected two sample sets from walls, plaster, and concrete located inside and outside of the buildings. A total of 25 + 38 specimens, respectively, were collected from different buildings. An aliquot of each sample was hand-grounded in an agate mortar, suspended in deionized water, and filtered on polycarbonate membrane filters (membrane diameter = 47 [micro]m, pore size = 0.4 [micro]m). We then placed portions of these filters on Al SEM stubs, each of which were covered with a thin gold conducting film by cathodic sputtering. The samples were analyzed subsequently at a magnification equal to 2,500x.
We used a Philips XL30 scanning electron microscope to recognize amphibole fibrous phases by their morphology; we used an energy-dispersion spectrometry system for x-ray microanalysis (EDAX DX4), and this enabled us to recognize the phases by their chemical composition.
III. Results
In 72% of the first sample set (25 samples) (Table 4), the same types of amphibole phases we observed in the Monte Calvario quarries were found. The presence of the tremolite-actinolite amphibole, with fibrous habit, was evident (Fig. 3). To obtain information about the time trend (at least from the 1950s to the 1990s) for the presence of amphibole phases in the buildings of Biancavilla, we selected a set of buildings for which building dates were known. The 38 samples collected from these buildings were analyzed for amphibole fiber concentration. Fibrous phases were detected in 27 specimens (71%), and fiber concentrations ranged from a few thousand up to more than 4 x [10.sup.4] fibers/mg of material. The time trend of fiber concentration in building materials is shown in Figure 4 for the time period from 1950 to the present.
[Figures 3-4 ILLUSTRATION OMITTED]
Table 4.--Environmental Samples Analyzed and Contamination by Amphibole Fibrous Phases
Positive samples
for amphibole
fibrous phases
Sample No. of samples n %
Sands 13 9 69
Plasters 12 9 75
Total 25 18 72
IV. Mineral Fibers in the Lungs of a Pleural Mesothelioma Case
IV. Material and Method
A study was conducted on the burden of mineral fiber in the lungs of an 86-y-old woman who died subsequent to a diagnosis of pleural mesothelioma. Her relatives established that she was a housewife who had been married to a farm laborer, and she had always lived in Biancavilla.
The autopsy samples of lung tissue (approximately 1 gm fresh weight) were placed in polyethylene containers with 5% ultrapure sodium hypochlorite and 30% hydrogen peroxide. The containers were kept at 30 [degrees]C until oxidation of the organic fraction was completed, as evidenced by solution limpidity (approximately 48 hr). To remove the lipidic component from the solution, we added acetone (in which lipids dissolve); we then shook it strongly and left the solution to stand until the water phase separated.
The mineral components, which were suspended in water, were then filtered on polycarbonate membrane filters (0.4-[micro]m pore size). We prepared the filters for SEM analysis by sputtering a thin gold film on them.
IV. Results
Several mineral fibers were detected in the lung tissue (Fig. 5). The results of x-ray microanalysis (Fig. 6) allowed us to identify the fibers as the tremolite-actinolite fibrous amphibole found in the quarries and in the building material of Biancavilla. The length of the fibers ranged from 12 [micro]m to 40 [micro]m, and the diameters ranged from 0.4 [micro]m to 1 [micro]m.
[Figures 5-6 ILLUSTRATION OMITTED]
The detection of the Monte Calvario amphibole in the lung samples indicates that the subject underwent an exposure to asbestos that was nonoccupational in nature. Had her exposure been occupational, we would have expected the presence of chrysotile, crocidolite, or amosite fibers. This case clearly demonstrates an environmental exposure associated with use of building materials from the quarries of Monte Calvario.
Overall Conclusions
In the town of Biancavilla, malignant pleural and peritoneal neoplasms (for which a correlation with exposure to breathable airborne mineral fibers is well established) are the mortality causes that, in the period considered (1980-1993), showed a significant increase, compared with expected values. We must emphasize that the increase in pleural neoplasms was particularly evident in the most recent years (1988-1993) and in subjects who were less than 65 y of age--especially females. The increase in peritoneal neoplasms--even if founded on only a few cases--appears concentrated in the female population. All of the data suggest that, for the population resident in Biancavilla, a mode of exposure to airborne fibers is related to environmental contamination, rather than, specific occupational activities.
The results of the environmental investigations indicate that the diffusion of the Monte Calvario amphibole fibers in Biancavilla was protracted through many decades. The magnitude of this diffusion during the past 30 or 40 y is likely the result of both the amount of material from the Monte Calvario quarries used in the local building industry and the mineralogic characteristics of the material itself.
Most likely the Biancavilla population was exposed to the amphibole fibers via several routes. Presumably, the presence of fibers embedded in plaster or mortar cannot cause a significant presence of airborne fibers, except in the case of specific work performed on the buildings (e,g,, demolitions, treatment of walls or ceilings, plaster surface removal). Conversely, individuals would most likely endure a heavy exposure to airborne fibers during the utilization of sands or grounded materials--before they are embedded in a compact matrix. Another possible route of exposure to airborne fibers occurs when wind causes dust dispersion during quarry activities.
The authors wish to thank Dr. G. Longo, Dr. C. D'Antona, and Dr. G. Gullo (Public Health Service of Adrano); Dr. G. Grasso (Unit of Pathology, Hospital of Caltagirone); and Dr. P. Ventura (Municipality of Biancavilla) for their valuable cooperation.
Submitted for publication May 16, 1999; revised; accepted for publication December 19, 1999.
Requests for reprints should be sent to Dr. Luigi Paoletti, Laboratorio di Ultrastrutture, Viale Regina Elena, 299, 00161 Rome, Italy.
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LUIGI PAOLETTI DOMENICO BATISTI CATERINA BRUNO Istituto Superiore di Sanita (ISS) Rome, Italy
MAURIZIO DI PAOLA National Board for Energy, New Technology and Environment (ENEA) CRE Casaccia Rome, Italy
ANTONIO GIANFAGNA Dipartimento di Scienze della Terra Universita "La Sapienza" Rome, Italy
MARINO MASTRANTONIO National Board for Energy, New Technology and Environment (ENEA) CRE Casaccia Rome, Italy
MASSIMO NESTI Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL) Rome, Italy
PIETRO COMBA Istituto Superiore di Sanita (ISS) Rome, Italy