Biancavilla
Pleural mesothelioma cases in Biancavilla are related to a new fluoro-edenite fibrous amphibole.
A cluster of deaths from pleural mesothelioma was previously reported fur Biancavilla, Italy, a city in eastern Sicily. An environmental survey suggested that the stone quarries located southeast of the city might be a source of asbestos exposure. The materials extracted from the quarries, used widely in the local building industry, contain large quantities of a fibrous amphibole that was initially referred to as an anomalous intermediate phase of sodium- and fluorine-rich tremolite-actinolite. A subsequent crystal chemistry investigation identified the mineral as fluoro-edenite, a new end-member of the edenite [right arrow] fluoro-edenite series. The material is very similar in morphology and composition to the minerals of the tremolite-actinolite series. To the authors' knowledge, fluoro-edenite becomes the 3rd mineral fiber (along with erionite and winchite), not yet classified as asbestos, with a demonstrable mesotheliomatogenous action in humans.
FLUORO-EDENITE is a new mineral species detected in Biancavilla, a city in eastern Sicily, Italy, characterized by a high incidence of pleural mesothelioma. In this study, we sought to provide new information about this fibrous amphibole and to discuss epidemiologic and environmental evidence supporting the etiologic role of fluoro-edenite in the occurrence of mesothelioma.
In a national survey of mortality from pleura mesothelioma in Italy from 1988 to 1992, a cluster of cases (N = 4) was detected in Biancavilla (standardized mortality ratio [SMR] = 417 [95% confidence interval {CI} = 142,954]). (1) From 1993 to 1997, an additional 8 cases were observed (SMR = 721 [95% CI = 359, 1,300]). (2)These findings prompted an ad hoc epidemiological investigation. Paoletti et al. (3) reported that 17 cases were identified and reviewed, their pathological diagnoses were confirmed, and history of exposures to asbestos was evaluated. Information on both occupational exposures and exposures to asbestos in the work place (in-site exposure) was available for 16 subjects There was no evidence of exposure for 9 subjects; 2 had probable exposure (a construction worker and a foundry worker). Exposure could neither be ascertained nor ruled out for the remaining 5 subjects, who worked in bricklaying, printing, or the clothing and paper industries.
Given that the occupational histories did not point to a common activity or source of exposure that could significantly increase the subjects' risk for developing mesothelioma, a general environmental source was considered. An environmental survey suggested that the general environmental source might be asbestos from the stone quarries located in Monte Calvario, southeast of the town. The materials extracted from the quarries--used widely in the local building industry--contained large quantities of fibrous amphiboles.
The Monte Calvario amphiboles were initially referred to by Paoletti et al. (3) as sodium (Na)--and fluorine (F)-rich tremolites and actinolites. The fibers were detected in the materials extracted from the quarries and in the plaster or mortar of the buildings in Biancavilla. The same fibers were detected in a lung tissue sample taken at autopsy from an 86-yr-old woman who resided in Biancavilla prior to succumbing to pleural mesothelioma. Other mineral fibers were not found in the sample, and it was impossible to reveal the presence of ferruginous bodies. Inasmuch as the quantity of the specimen was very limited, it was impossible to conduct histological investigations, the purpose of which was the elucidation of pathological changes related to an exposure to asbestos. No lung tissue samples were available from the other identified cases.
A subsequent crystal-chemistry investigation of the Monte Calvario amphiboles (4) identified the mineral as fluoro-edenite--a new end-member of the edenite [right arrow] fluoro-edenite series. The finding was confirmed by the Commission on New Minerals and Mineral Names on January 30, 2001. (5)
Environmental and Geological Investigations
The fluoro-edenite from Biancavilla (ideal formula: Na[Ca.sub.2][Mg.sub.5][Si.sub.7]Al[O.sub.22][F.sub.2]) is transparent, intense yellow with habit from prismatic to acicular. It is also fibrous and asbestiform, occurring in autoclasts of grey-red altered benmoreitic lavas where it is generally associated with potassium-feldspar and plagioclase, quartz, clino-and orthopyroxenes, fluoro-apatite, ilmenite, and hematite. In Table 1 are shown relevant mineralogical data for fluoro-edenite.
In the Monte Calvario area, the fluoro-edenite mineralization process yielded mainly prismatic, evenly sized acicular crystals (Fig. 1). Similar fibers have recently been found in neighboring areas of the quarry (Fig. 2), but in a different volcanic formation. The fibers are similar in size and morphology to some amphibolic asbestos fibers (tremolite, actinolite, antophyllite); sometimes they occur as elastic and tensile (filamentous) fibers (Fig. 2) (size: < 0.5 [micro]m in width to > 10 [micro]m in length).
[FIGURES 1-2 OMITTED]
The fluoro-edenite at Monte Calvario is found in cavities and cracks of benmoreitic lava that has been meta-somatized by hot, F-rich fluids. The asbestiform fluoro-edenite is found in refall pyroclastic products and scoriae that have been greatly altered; these are mainly found in the northwest of Monte Calvario. The finding of amphibolic fibers near Monte Calvario points to a very complex volcanic process with several evolutionary stages. It also suggests that the process may have also occurred in other areas that have not yet been identified, perhaps because the products are not at the surface or perhaps they have not yet been quarried.
Discussion and Conclusions
The physical processes that determined the genesis of this new amphibole are not yet understood. Among the various hypotheses posited, the most plausible points to an upsurge of very hot fluids directly from the magma chamber. These fluids altered and metasomatized the previously emplaced volcanic products (lavas, pyroclasts). Fluoro-edenite appears to have formed during this metasomatic process because there was an abundance of fluorine in the contaminating fluid. Concurrently, the rising fluid also conditioned other nionlavic formations peripheral to Mount Calvario and gave rise to asbestiform fluoro-edenite. The different morphology of the fibers may be ascribed to different rates of cooling of the materials affected: larger fluoro-edenite crystals in the central part of the dome represent a slower cooling rate, whereas asbestiform fibers in the more peripheral areas represent a faster cooling rate.
This research note clarifies the type of amphibole mineral found in the Biancavilla area. Although it was identified preliminarily as an intermediate mineralogical phase between Na-F-tremolite and Na-F-actinolite, (3) we now know that the yellow amphibole corresponds to fluoro-edenite and that the brown amphibole is the same fluoro-edenite, but it is rich in microlamellar hematite and is arranged parallel to the cleavage planes of the fluoro-edenite crystals. The tremolite-actinolite phases hypothesized previously are not present in the volcano products from Monte Calvario. (3) To date, we have not found mineral fibers other than fluoro-edenite.
The available evidence strongly suggests a causal link between exposure to fibrous fluoro-edenite and the occurrence of pleural mesothelioma in Biancavilla. It is still unclear whether the materials extracted from the stone quarries of Monte Calvario and used in the local building industry represent the only route of exposure for the population; the current data on the diffusion of the new fibrous amphibole are not conclusive. A study on the geologic and mineralogical structures of the region near Biancavilla must be completed if the health risks to the population are to be evaluated fully.
No ad hoc studies on the incidence of mesothelioma in areas of Italy characterized by the presence of tremolite in soil are available. Preliminary observations based on geographic mortality data showed increased death rates from malignant pleural neoplasms in 27 municipalities of the Susa and Chisone Valleys (Western Alps) for the years 1988 to 1997 (SMR = 505 [95% CI = 164, 1,179] N = 5). This finding was not reproduced in 5 municipalities of the Malenco Valley (Central Alps), where 1 case was observed versus 0.1 expected. (2 The results from the mesothelioma mortality study are preliminary, as they were based on death certificates only and lack information about exposure at the individual level. Furthermore, no single municipality identified as having significantly increased mortality from mesothelioma has evidence of tremolite exposure.
The findings to date do not indicate that the carcino-genicity of tremolite may be weak or even absent, but, rather, corroborate the uniqueness of the patterns of exposure to fluoro-edenite in Biancavilla. Fluoro-edenite was present in the materials used by the local building industry, and these were widely used for dwellings and road pavements in Biancavilla. As a consequence, thousands of people were exposed to fluoro-edenite for decades. To our knowledge, this is only the 3rd fiber (other than erionite (6) and winchite (7), not yet classified as asbestos, that has a demonstrable mesotheliomatogenous action in humans.
Fluoro-edenite fibers from Biancavilla are not yet regulated by the Occupational Safety and Health Administration or the U.S. Environmental Protection Agency because they are new mineral fibers, which are distinct from the well-known fibers listed as asbestos. This represents a nomenclature and terminology problem that should be addressed immediately. Fibers not yet classified as asbestos--but which have a direct relationship with diseases--need regulation.
Submitted for publication February 9, 2002; revised; accepted for publication August 13, 2002.
Requests for reprints should be sent to Dr. Luigi Paoletti, Department of Ultrastructures, Istituto Superiore di Sanita, Viale Regina Elena 299, 00161 Roma, Italy.
E-mail: paoletti@iss.it
Table 1.--Relevant Mineralogical Data for Fluoro-Edenite from
Biancavilla (Extracted from Gianfagna and Oberti, 2001) (4)
Unit formula (O + OH +
Cell parameters Optical properties F = 24)
a = 9.847(2) [alpha] = 1.6058(5) [sup.A]([Na.sub.0.56]
b = 18.017(3) [beta] = 1.6170(5) [K.sub.0.15])
c = 5.268(2) [gamma] = 1.6245(5) [sup.B]([Na.sub.0.30]
[Angstrom] 2[V.sub.calc] = [Ca.sub.1.62]
[beta] = 104.84(2) 78.09[degrees] [Mg.sub.0.03]
[degrees] [Mn.sub.0.05])
V = 903.45 [sup.C]([Mg.sub.4.68]
[[Angstrom].sup.3] [Fe.sup.2+.sub.0.19]
[Fe.sup.3+.sub.0.10]
[Ti.sup.4+.sub.0.03])
[sup.T]([Si.sub.7.42]
[Al.sub.0.58])
[O.sub.22]
[sup.o.sub.3][([F.sub.
1.98] [C1.sub.0.02]).
sub.2]
References
(1.) Di Paola M, Mastrantonio M, Carboni M, et al. La mortalita per tumore maligno della pleura in Italia negli anni 1988-1992. [Mortality from malignant pleural neoplasms in Italy in the years 1988-1992.] Rapporti ISTISAN 96/40. Rome, Italy: Instituto Superiore di Sanita, 1996.
(2.) Mastrantonio M, Belli S, Binazzi A, et al. La mortalita per tumore maligno della pleura nei comuni italiani, 1988-1997. [Mortality from malignant pleural neoplasms in Italy, 1988-1997.] Rapporti ISTISAN. Rome, Italy: Instituto Superiore di Sanita, 2002.
(3.) Paoletti L, Batisti D, Bruno C, et al. Unusually high incidence of malignant pleural mesothelioma in a town of eastern Sicily: an epidemiological and environmental study. Arch Environ Health 2000; 55(6):392-98.
(4.) Gianfagna A, Oberti R. Fluoro-edenite from Biancavilla (Catania, Sicily, Italy): crystal chemistry of a new amphibole end-member. Am Mineralogist 2001; 86:1489-93.
(5.) Grice JD, Ferraris G. New minerals approved in 2000 by the Commission on New Minerals and Mineral Names. IMA. (No. 2000-049, p. 1001). Eur J Mineral 2001; 13(5):995-1002.
(6.) Temel A, Gundogdu MN. Zeolite occurrences and the erionite-mesothelioma relationship in Cappadocia, central Anatolia, Turkey. Mineralium Deposita 1996; 31:539-47.
(7.) Wylie A, Verkouteren J. Amphibole asbestos from Libby, Montana: aspects of nomenclature. Am Mineralogist 2000; 85:1540-42.
PIETRO COMBA
Higher Institute of Health
Rome, Italy
ANTONIO GIANFAGNA
Department of Earth Science
University "La Sapienza"
Rome, Italy
LUIGI PAOLETTI
Higher Institute of Health
Rome, Italy