Document MM09nZgxK4a9Njk5zg9wm488j

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GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Geological Society ofAmerica Special paper 373 2003 History ofasbestos discovery and use and asbestos-related disease in context with the occurrence ofasbestos within ophiolite complexes Malcolm Ross* Robert P. Nolan* Earth and Environmental Sciences ofthe Graduate School and University Center of The City University ofNew York, 365 Fifth Avenue, New York, New York 10016, USA ABSTRACT Two ancient asbestos mines, one near Karystos, Greece, and the other southeast of Mount Troodos, Cyprus, were located in what we now know to be ophiolite terrane. Evidence suggests that asbestos was discovered and utilized in Cyprus, perhaps as long as 5,000 years ago, for manufacture of cremation cloths, lamp wicks, hats, and shoes. Some of the adverse health effects of asbestos became known only in the early twentieth century, but it was not until the 1960s that the asbestos-related diseases-- asbestosis, lung cancer, and mesothelioma--were fully understood. Approximately 85% of the world's asbestos was produced from ophiolite com plexes, most of which was the chrysotile variety; tremolite, actinolite, and anthophyllite asbestos accounting for only a few percent of the total. Asbestos minerals crystallize within tectonized ophiolites--along shear, fault, and dilation zones, and at contacts with intruded dikes and sills. Important chrysotile asbestos mines are found in the ophiolites of eastern Canada, the Russian Urals, California, northwest Italy, northern Greece, and Cyprus. A high incidence of mesothelioma, a cancer of the lung lining, is reported among residents of villages located within or near ophiolite com plexes in Greece, Turkey, Cyprus, Corsica, and New Caledonia. These villagers were exposed to tremolite asbestos while processing stucco and whitewash for application to homes. Asbestos contamination in various geographic localities has generated con cern about health risks and has prompted costly remedial actions, especially in the United Kingdom and the United States. A scientific basis for public policy is offered to address the utilization of asbestos-bearing rocks. Keywords: mineral fibers, asbestos, chrysotile, tremolite, serpentines, serpentinite, lung cancer, mesothelioma, ophiolite. INTRODUCTION Ophiolite complexes, including the associated serpentinite belts, are found in many parts of the world. It was in these rocks that asbestos was first discovered and utilized as long as 5,000 years ago and from which ~85% of the world's asbestos was pro duced, most being chrysotile asbestos. This paper is intended to *Mailing address, Ross: 1608 44th Street, NW, Washington, D.C. 20007, USA. E-mails: Ross--mrdrr@earthlink.net; Nolan--rnolan@gc.cuny.edu. give the ophiolite specialist insight to the importance of ophiolites as a source of chrysotile, tremolite, actinolite, and anthophyllite asbestos by presenting their mineralogical descriptions, the nature of crystal growth of the asbestos minerals, their mode of occur rence within ophiolite complexes, and descriptions of some of the more important ophiolite-hosted asbestos deposits. We will discuss the origin of the Latin and English word "asbestos" from the writings of the ancient Greek and Roman philosophers; pres ent a history, from ancient times to the present, of the discovery, production, and utilization of the various asbestos minerals; and Ross, M., and Nolan, R.P., 2003, History of asbestos discovery and use and asbestos-related disease in context with the occurrence of asbestos within ophiolite complexes, in Dilek, Y., and Newcomb, S., eds., Ophiolite concept and the evolution of geological thought: Boulder, Colorado, Geological Society of America Special Paper 373, p. 447-470. For permission to copy, contact editing@geosociety.org. 2003 Geological Society of America. 447 448 M. Ross and R.P. Nolan present an early history of the development of an understanding of asbestos-related disease that took such a toll on asbestos workers' lives. Epidemiological studies are presented to show that asbes tos workers who experienced uncontrolled asbestos exposures, such as miners, millers, and insulators, developed three serious diseases: asbestosis (scarring of the part of the lung where gas exchange takes place), lung cancer, and mesothelioma (cancer of the lining of the lung and abdominal cavity). From British medical pneumoconiosis studies of asbestos workers in the early part of the twentieth century to the recent epidemiological studies, there developed a great concern over the health effects of asbestos and as a result many countries have promulgated strict regulations for the use of asbestos (WHO, 1989). More recent bans on the mineral's use have been adopted or proposed (see Wilson et al., 2001). The Fifth Circuit Court of Appeals struck down the U.S. Environmen tal Protection Agency's (EPA) proposed ban on asbestos in 1991, citing the EPA's failure to pursue the least burdensome, most rea sonable regulation required to protect the environment adequately (United States Court of Appeals, 1991). In addition to chrysotile asbestos, tremolite and actinolite asbestos minerals are also found in ophiolites, but have been mined only in small quantities. As will be discussed, these two asbestos minerals present a much more serious health problem to miners and other workers than does chrysotile asbestos. Six ophiolite localities in Turkey, Greece, Cyprus, Corsica, and New Caledonia are described, where the residents of nearby rural villages were exposed to tremolite asbestos through its use as ingredients for stucco (a fine plaster composed of cement mixed with asbestos added for strengthening) and whitewash (usually a mixture of water, asbestos, and calcium carbonate). Examples will be presented of some ofthe asbestos mitigation efforts now being undertaken in the United States and Cyprus. In the discussion, we present the scientific basis for developing a pub lic policy to address the health hazards when mining or construc tion activities occur in rocks that contain fibrous minerals. ORIGINS OF THE WORD "ASBESTOS" The various words used in antiquity to denote the asbes tos minerals--including asbestos, asbestus, asbestinon, asbest, asbeste, asbeston, abeston, amiantos, amiantus, amianthus, amiant, and amiante--can be traced back to the writings of the ancient Greek philosophers and their use of two words--aptavxoq and aoPeoxoq. The Greek word aptavxoq (transliterated as "amian tos"), when used as a noun is synonymous with the English word asbestos, and when used as an adjective can mean pure or unde filed (G.E.L., 1940, p. 83). The Greek word aoPeoxoq (properly transliterated as "asvestos"--not "asbestos"), when used as a noun means lime, quicklime, or unslaked lime (CaO), and when used as an adjective, can mean inextinguishable, unquenchable, or not quenched (G.E.L., 1940, p. 255). Note, that quenching or slaking of calcium oxide with water produces calcium hydroxide. Latin translations of the Greek words for asbestos and quicklime have caused some confusion that is perhaps related to the difficulty of translating the complex noun and adjective declensions of Greek into Latin, an equally complex language, to the interchange of noun modifiers and nouns, and to the Greek versus Latin trans literation of the letter p. The Greek physician, Pedanius Dioscorides of Cilicia (40-90 A.D.) reports of an "undefiled stone," aptavxoq fo,0oq-- transliterated as "aminatos lithos," that occurs in Cyprus and resembles fissile alum that can be woven and is not consumed by fire (MateriaMedica, 5, 138; see also G.E.L., 1940, p. 83 and O.E.D., 1933, p. 280). In modern Greek usage, the noun ^t0oq ("lithos") is omitted and replaced with aptavxoq ("amiantos"), synonymous with the Latin and English noun asbestos, the Ger man and Russian noun asbest, the French nouns asbeste and amiante, and the Italian and Spanish nouns asbesto and amianto. The ancient Greek writers (e.g., Dioscorides, Materia Med ica,, 5, 115; see also G.E.L., 1940, p. 255 and O.E.D., 1933, p. 480) used the noun aopeoxoq ("asvestos") to mean quicklime; a mean ing retained in modern Greek; however, Pliny the Elder (Caius Pliny Secundus, 23-79 A.D., Natural History, Book 19, paragraph 20; see also Rackham, 1961, p. 432-433), apparently misunder standing the use of this word by the early Greek philosophers, replaced the Greek noun for quicklime (aopeoxoq) with the dubi ous Greek word aapeaxtvov (G.E.L., 1940, p. 255), which he interpreted to mean a non-combustible material. Pliny then trans literated aopeoxtvov into the Latin noun "asbestinon," alluding to an incombustible linen, cleansed by fire, and used as shrouds for royalty during cremation. Pliny also refers to this incombustible linen as linum vivum--live linen. Pliny was undoubtedly referring to what we now know as asbestos cloth but reported that the mate rial came from a plant that "grows in the deserts and sun-scorched regions of India" (Rackman, 1961, p. 433). A computer search for the many variations of the word for asbestos that possibly may have been used in the 37 books of Pliny's Natural History (which is copied onto an Internet web site; Thayer, 2002) revealed that Pliny, in addition to "asbesti non" (Book 19, 20), used the words "amiantus" (Book 36, 139; see also Bailey, 1932, p. 120-123, 256-257) and "asbestos" (Book 37, 146, Thayer, 2002). Pliny states that "amiantus" resembles alumen in appearance and is not destroyed by fire. The alumen of Pliny is probably not alum as we know it (potas sium aluminum sulfate), but possibly an iron sulfate efflorescent produced by decomposition of pyrite (see Hoover and Hoover 1950, footnote 11, p. 572). In using the word "amiantus," Pliny may indeed be describing an asbestos mineral, but relating it to alumen because of similarity of certain physical properties. In Book 37, 146, Pliny states that iron colored "asbestos" is found in the Arkadian mountains (located in the central Pelopon nesus of Greece) perhaps suggesting that this fibrous material has a mineral origin. Here Pliny has taken the Greek word "asvestos" (quicklime) to mean something quite different--a fibrous min eral, now referred to as "asbestos" in both the Latin and English languages. It is not at all clear whether Pliny really understood the geological origin of asbestos, whereas ancient Greek writers, such as Strabo, Dioscorides, and Theophrastus, certainly did. History ofasbestos discovery and use 449 In summary, various words for asbestos have entered the vocabulary ofLatin and other languages; the words amiantus, ami anthus, amiant, amiante, and amianto were derived from the Greek word aptavxoq--"amiantos," whereas the words asbestos, asbestus, asbestinon, asbest, asbeste, asbeston, abeston, and asbesto were derived from the Greek word aaPeaxoq--"asvestos". HISTORY OF ASBESTOS DISCOVERY, PRODUCTION, AND UTILIZATION Early Beginnings While the general use of asbestos in international commerce dates only to the late nineteenth century, its utility in human cul ture goes back at least 4,500 years. Archeological studies (Europaeus-Ayrapaa, 1930) show that inhabitants of the Lake Juojarvi region of East Finland knew how to strengthen earthenware pots and cooking utensils with an asbestos mineral, later identified as anthophyllite (anthophyllite asbestos was mined commercially in East Finland between 1918 and 1975). According to Huuskonen (1980; see also Europaeus-Ayrapaa, 1930 and Noro, 1968), the use of asbestos-strengthened ceramic wares began during the Stone Age and continued throughout the Bronze Age and into the Iron Age. The use of such utensils spread over a wide area of Fin land, Scandinavia, and Russia. One of the most important uses of asbestos in the twentieth century--to strengthen materials--was used for this purpose several thousand years ago. There is also evidence that asbestos was discovered and uti lized in Cyprus during classical times, perhaps as long as 5,000 years ago, for manufacture of cremation cloths, lamp wicks, hats, and shoes (Dioscorides, Materia Medica, 5, 138). Bowles (1955, p. 9) suggests a location for the ancient asbestos depos its, and states that Cyprus was a well known source of asbestos in ancient times and that "although it is difficult to determine, from early references the exact location of the ancient deposit, probably it was southeast of Mount Troodos in a village known as Amianto the identity of which is lost." Evans (1906, p. 145) states that sixteenth-century travelers referred to the existence of abandoned asbestos mines near the village of Paleandros or Pelendria. Pelendria (now Pelendri) is situated within the Troo dos ophiolite complex and ~6 km southeast of the Mount Troodos chrysotile asbestos mine; however, Dr. George Constantinou, former head of the Cyprus Geological Survey Department, suggests that asbestos was mined in ancient times near the towns of Vavla, Vasa, and Apsiou, 25 km southeast of Mount Troodos. These towns are located within the Akapnov Forest, a large area of ophiolite terrane within the Arakapas (transform) Sequence. We suggest that the ancient asbestos deposits were located within the Akapnov Forest area; the deposit near Pelendri may have been developed much later and prior to opening of the nearby Mount Troodos chrysotile asbestos mine in 1904. The descriptions of asbestos use in Greece clearly goes back more than 2000 years. Herodotus (ca. 484-425 B.C.) clearly documented the use of asbestos for lamp wicks in the early Greek civilization. The Greek philosopher Theophrastus (ca. 372-287 B.C.), one of Aristotle's students, was perhaps one of the first to carefully describe the mineral we now call asbestos as "a stone, in its external appearance somewhat resembling wood, on which, if oil is poured, it burns; but when the oil is burnt away, the burning of the stone ceases, as if it in itself not liable to such accidents" (Hoover and Hoover, 1950, p. 440, footnote 5). Plutarch (ca. 46-120 A.D.) recorded that the vestal virgins used "perpetual" lamps to serve Rome's sacred fire (the fabrication of asbestos lamp wicks, such as described by Herodotus and Plu tarch, probably was an important cottage industry in Greek and Roman times). Pliny, as discussed before (Book 19, 20), refers to tablecloths, lamp wicks, and a rare and costly asbestos cloth-- lithium vivum--the funeral dress of kings. Pliny's reference to iron colored asbestos occurring in the Arkadian mountains (Book 37, 146) is supported by the town history of Kandyla, Province of Arkadia, central Peloponnesus, Greece. In a translation from the original ancient Greek, it is reported that early in the first mil lennium there was a merger of three towns into one--Kandyla. Further, it is stated that after the merger "the inhabitants began to construct homes that were solid, with the use of such materials as stone and asbestos" (Deligiannis, 2002, p. 1). As will be men tioned latter, villagers in the rural areas of Greece, as well as in other countries, commonly applied asbestos-bearing stucco and whitewash to their homes. The Greek geographer, Strabo (64 B.C.-21 A.D.), in Geographia, Book 10, (see also Bailey, 1932, p. 256) referred to a "Karystian stone" obtained from quarries near Karystos (Karistos), a town on the southern tip of the Greek island of Euboea (Evvia). Hoover and Hoover (1950, p. 440, footnote 5) quoting from Strabo (Book 10, 1): "at Carystus (Karystos) there is found in the earth a stone, which is combed like wool, and woven, so that napkins are made of this substance, which when soiled, are thrown into the fire and cleaned, as in the washing of linen." Examination of geologic maps of Evvia shows extensive out crops of ophiolitic rocks in the north-central region of the island and one smaller outcrop ~30 km north of Karystos (Rassios and Smith, 2000, fig. 2; Geological Map of Greece, Division of Geology and Economic Geology, Athens, 1983). Thus, this ancient source of asbestos known to the ancients as "Karystian stone," may have been quarried within ophiolite terrane. There are also numerous references (see Bowles, 1955. p. 8 10) to the use of asbestos in post-Roman times and before the start of the modern asbestos industry in the late part of the nineteenth century. The origin of asbestos remained a subject of fanciful speculations into the Middle Ages, when alchemists made claims that asbestos was the hair of a type of fire-resistant salamander (Alleman and Mossman, 1997). Since at least the early part of the sixteenth century, the image of the salamander has been symbolic for asbestos. Probably the most famous anecdote is that of Char lemagne (or, according to some writers, Charles V) astonishing his guests by cleansing a tablecloth by throwing it into a fire. Marco Polo, in his travels through Siberia during the thirteenth century, mentions the "amianthus" cloth, which resisted the action of fire. 450 M. Ross and R.P. Nolan As early as 1720, chrysotile asbestos was commercially mined in the Urals Region of Russia along the Tagyl River in the Middle Urals. The silky mineral fibers were woven into cloth to fabricate aprons, gloves, and caps for the high-tempera ture shops of the eighteenth-century metallurgical plants that were common in the Urals. In 1722, a sample of the asbestos cloth was presented to Peter the Great (Kashansky, 1999). Start of the Modern Industry In the 1860s and 1870s, the market for asbestos products rapidly expanded, probably for three reasons: the need for insulation for the new steam technology, the formation of an international consortium of Italian and English entrepreneurs, and the reopening of the asbestos deposits in northern Italy and simultaneous development of the vast chrysotile resources in Quebec, Canada. By 1890, the modern asbestos industry was full blown, with hundreds of applications being introduced (Jones, 1890; Alleman and Mossman, 1997). Chrysotile and tremolite asbestos deposits in the Susa, Lanzo, Aosta, and Val Malenco areas of the Italian Alps were first exploited in Roman times, but it was not until the early 1800s when manufacture of asbestos threads, fabrics, and paper was perfected, that the alpine deposits became economi cally important. Between 1860 and 1875, several new Italian companies formed to advance the technology of fabrication of asbestos into spun products, rope packings, and heat-insulat ing board. Exhibits by these companies at the Paris Universal Exposition in 1878 helped to bring these asbestos products to international attention. (Ross, 1981; Bowles, 1955). Marcuse (1930) describes the first discovery of asbestos in the Province of Quebec, Canada by the early French settlers who referred to the local asbestos (now known to be chrysotile) as "Pierre a Coton" (the cotton stone). Bowles (1955) reports that the first small deposit of asbestos was discovered near St. Joseph, Quebec in 1860 and samples of the mineral were exhib ited in London in 1862; however, the first deposit capable of major development was discovered near Danville, Quebec, in 1877. Active mining began in 1878, when 50 tons of fiber was produced. By 1885, seven asbestos mines, centered around the town of Thetford Mines, were in production. Asbestos was discovered in the Ural Mountains near the city of Ekaterinburg in the early part of the eighteenth cen tury and the fiber was used sporadically in textile production. Systematic development of the Ural deposits, however, did not began until the huge Bazhenovskoye deposit of chrysotile asbestos was discovered near Asbest City in 1884. Commer cial mining of this deposit began in 1886, and by 1889 24,000 tons of chrysotile asbestos had been produced. Since 1918, the mines and mills have been operated by the Uralasbest Company (Shcherbakov et al., 2001). The occurrence of "crocidolite" asbestos was discovered in 1812 in the Profret area, Northern Cape Province, South Africa, but it was not until 1893 that asbestos production began near the town of Koegas and in 1926 near the Pomfret area (Beukes and Dreyer, 1986). "Amosite" asbestos was discovered near the town of Penge, Transvaal Province, South Africa, in 1907, and commercial production began in 1916 (Bowles, 1955). Asbestos Production From the time of the first recorded use of asbestos by Stone Age man to 1900, total world production was probably between 200,000 and 300,000 metric tons. Of this, 150,000 tons were pro duced in Quebec, Canada (Ross, 1981). After World War I, use of asbestos greatly increased; total world production of all forms of asbestos between 1931 and 1999 was ~166 million metric tons (Ross and Virta, 2001), of which 90 to 95% was the chrysotile variety. A large percentage of the total chrysotile production was from ophiolite complexes. Approximately 3 million metric tons each of "amosite" and "crocidolite" asbestos have thus far been mined worldwide, and ~350,000 metric tons of anthophyllite asbestos was mined in east Finland (Huuskonen et al., 1980). Commercial production of tremolite and actinolite asbestos has been small and sporadic. Russia is the leading producer of asbes tos, followed (in decreasing amount of production) by China, Canada, Brazil, Zimbabwe, and Kazakhstan. At present, the only producing asbestos mine in the United States is located within the New Idria serpentinite, located at the south end of the Diablo Range, California. THE ASBESTOS MINERALS Chrysotile Asbestos Chrysotile asbestos, the only fibrous member of the serpentine mineral group, has the ideal chemical formula Mg3Si2O5(OH)4. Small amounts of aluminum, iron, manganese, calcium, potassium, and sodium may enter the crystal structure of this mineral. The chrysotile fibers consist of long hollow "rolled up" tubes and each fibril is ~25 nanometers in diameter, with lengths varying from well under one micrometer for an individual fibril to well over 10 cm for fiber bundles (Fig. 1). Chrysotile is identified by a combination of optical properties, quantitative chemical analysis, polyfilamentous bundles, size, hollow tube morphology, and a characteristic powder x-ray diffraction or selected area electron diffraction pattern (Langer and Nolan, 1994; Wicks, 1999). Chrysotile asbestos is by far the most common asbestos mineral, generally occurring at trace levels in most serpentinites, whereas the commercial deposits contain several volume percent of this mineral. Amphibole Asbestos The three main forms of amphibole asbestos found in ophiolite complexes are: (1) anthophyllite asbestos, ideally (Mg,Fe2+)7 Si8O22(OH)2, where 0 to 50 atom percent of Mg can be replaced by Fe2+; (2) tremolite asbestos, ideally Ca2(Mg,Fe2+)5Si8O22(OH)2, History ofasbestos discovery and use 451 Figure 1. Transmission electron photomicrograph of chrysotile asbestos displaying polyfilamentous bundles offibers and individual fibril having a central capillary associated with the hollow tube structure. where 0 to 10 atom percent of Mg can be replaced by Fe2+; and (3) actinolite asbestos, ideally Ca2(Fe2+,Mg)5Si8O22(OH)2, where 10 to 50 atom percent of Mg can be replaced by Fe2+ (Leake et al., 1997). The amphibole asbestos minerals are char acterized by their chemical composition, distinctive diffraction patterns, generally long straight fiber morphology, and trans parency to electrons when viewed by transmission electron microscopy. Fibers typically vary in width from 0.1 to >1 micrometer and in length from a few micrometers to several centimeters. Anthophyllite asbestos was mined mostly within an ophiolite complex located in the Paakkila (Tuusniemi) area of East Finland. With the close of the Finnish mines in 1975, there is now very little anthophyllite mined anywhere in the world. Small amounts of anthophyllite were mined earlier in this cen tury within the serpentinite belt of the eastern United States, particularly in the states of Georgia, Maryland, and North Carolina. Minor amounts of tremolite asbestos and actinolite asbestos have been mined in various serpentinite belts, but were (with a few exceptions) of little commercial importance and mined mostly for local uses. Tremolite and actinolite asbestos is still possibly being mined to a very limited extent in ophiolites of Greece and Turkey, and perhaps in ophiolites of Cyprus and Iran. The asbestos minerals in the tremolite-actinolite series are associated with environmental mesotheliomas in several countries and are much more hazardous than chrysotile and anthophyllite asbestos. Thus, it would be useful for geologists to particularly note their presence and any mining activity dur ing field investigations. The two other commercial asbestos minerals, which do not occur in ophiolite complexes, have been important in com merce. These are: (1) grunerite asbestos, (Fe2+,Mg)7Si8O22(OH)2, usually referred to colloquially as "amosite" (from the acronym AMOS, representing Asbestos Mines of South Africa), which was mined only in metamorphosed banded iron formations of the Cape Province of South Africa; and (2) riebeckite asbestos, Na2(Fe2+,Mg)3Fe23+Si8O22(OH)2, usually referred to colloquially as "crocidolite," which was mined in four localities--in the banded iron formations of the Transvaal and Cape Provinces of South Africa, in the iron formations of the Hammersley Range of Western Australia, and in the Cochabamba area of Bolivia. The geologic occurrence and mineralogy of the asbestos miner als are discussed in detail in Ross (1981, 1984), Skinner et al. (1988), and Veblen and Wylie (1993). It should be noted that five of the six minerals designated as asbestos (tremolite, actinolite, anthophyllite, grunerite, and 452 M. Ross and R.P. Nolan riebeckite asbestos) can also occur in a non-fibrous form. It is important to use the mineralogical definition of asbestos for iden tification. Historically, non-asbestos fibers (for which there is no evidence of an asbestos health hazard) have occasionally been misidentified as asbestos (Langer et al., 1991; Langer, 2001). Crystal Growth of Asbestos Fibers Most asbestos appears to crystallize under very special conditions that occur within rock formations that are under going intense deformation characterized by folding, faulting, shearing, and dilation. Such deformations are often accom panied by the intrusion of magmatic fluids forming dikes and sills. The fibers crystallize in high strain environments, such as within folds, shear planes, faults, dilation cavities, and at intru sion boundaries. Ophiolite complexes are highly tectonized rocks containing many of these deformation attributes, thus they present conditions ideal for fiber formation. Slip-fibers are formed within the fault and shear zones, the fibers crystallizing or recrystallizing from solutions that move within the two rock faces that compose the shear or slip plane-- thus the term slip-fiber (Fig. 2). We observed this type of fiber formation in samples collected from a shear zone within a meta morphosed iron formation in northeastern Minnesota. There non-fibrous ferroactinolite had come into contact with low tem perature acidic solutions that were moving through an active shear zone, causing the amphibole to recrystallize into a fibrous form having the fiber axis lying parallel to the shear and flow plane. Nolan et al. (1999) report on the occurrence of grunerite asbestos ("amosite") in a similar iron formation in Michigan. They state that "grunerite asbestos is developed within quartz- ankerite-stilpnomelane veins and along their contacts with the host rock and sills. The veins are deformed and exhibit signs of shearing, brecciation, faulting, and folding" (p. 3413). Cross-fibers occur within cracks formed when the rock undergoes dilation due to tectonic stress, a process in which parallel cracks and fissures form open spaces in the rock. The process of folding in layered rocks can also produce openings or dilation cavities between adjacent layers. Asbestos crystallizes from a fluid phase, the fibers nucleating on a wall of the crack or cavity and growing toward the opposite wall--thus the term cross-fibers. Examples of cross-fiber growth within folds occur in the "crocidolite" and "amosite" deposits of South Africa and the "crocidolite" deposits of Western Australia. There, the fibers crystallized only where the Precambrian banded iron forma tions were folded into monoclines, inducing splitting and dila tion cavities between mesobands (Dreyer and Robinson, 1981; Trendall and Blockley, 1970). ASBESTOS AND DISEASE Early History of Asbestos-Related Disease While great advances were being made to advance the technology of asbestos mining and milling and invention of new uses for asbestos through product development, giving tangible benefits to society, asbestos workers were dying of asbestosrelated diseases from exposure to asbestos dusts. The ancient world recognized the remarkable properties of asbestos and wrote about the "magic mineral" and its ability to resist fire; however, the health effects associated with the inhala tion of asbestos fiber were not known to any of the ancient writ- Figure 2. Large sheets of nemalite (fi brous brucite-chrysotile), occurring as a slip-fiber in Mine Jeffrey, Quebec, Canada. The Canadian coin for scale is 2.8 cm in diameter. History ofasbestos discovery and use 455 workers (Ohlson and Hogstedt, 1985); (4) English asbestos cement factory workers (Gardner et al., 1986); and (5) British friction product workers (Newhouse and Sullivan, 1989). The health experience of the five above-mentioned cohorts is in great contrast to many other asbestos workers who worked under the historically high exposures, such as occurred in asbes tos textile manufacturing, during installation and removal of asbestos in heating and electrical conduits, in poorly ventilated asbestos factories, and in workplaces and mines where there was exposure to large quantities of "crocidolite" and "amosite" asbestos dust (Ross, 1981, table 4). Worker cohorts engaged in such activities were often exposed to dust levels of hundreds of fibers per ml (Gibbs and DuToit, 1973; Doll and Peto, 1985). Studies of Those Who Had a Non-Occupational Exposure to Chrysotile Asbestos Mines within the towns of Thetford Mines and Asbestos, located in the province of Quebec, Canada, have produced over 40 million metric tons of chrysotile asbestos since first opening in 1878. Many mines have closed, but two large-capacity mines are still producing asbestos. These two towns have a combined population of 30,000, and a large number of the male residents work, or have worked, in the asbestos mines and mills. Most of the asbestos workers are male; very few are female. Historically, the ambient asbestos exposures were high in these towns and res idents were continually exposed to asbestos dust from the nearby mines, mills, and mine waste dumps. Camus et al. (1998) give estimates of the number of ambient asbestos fibers (those longer than 5 micrometers) per milliliter (f/ml) of air in the two asbestos towns for the period 1900-1989. They state that average levels exceeded 1 f/ml during World War II and into the early 1950s. Thus, ambient chrysotile asbestos dust levels in these Quebec towns prior to the introduction of modern dust control technol ogy in the 1970s were ~230 to 23,000 times the average levels found in schools with asbestos insulation (Ross, 1995, p. 186). A mortality study was made by Siemiatycki (1982) of 1130 deceased women who had lived in Thetford Mines and Asbestos but did not work in the asbestos industries. This study shows that the health of these women was unaffected by these very high non-occupational 24-hour-a-day lifetime exposure to asbestos dust. The standard mortality ratio (SMR = observed deaths/expected deaths) for all cancer in these women is 0.91, for lung cancer is 1.07, for digestive cancer is 1.06, and for non-malignant respiratory disease is 0.58. None of these SMRs is statistically different from the control cohort composed of unexposed women of similar socioeconomic background liv ing outside the asbestos mining townships (SMRs >1.2 might imply a statistically significant health risk). A previous study by Graham (1981) also showed no excess cancer among the female residents of these Quebec mining towns (also see Ross, 1984, p. 82-85). More recently, Camus et al. (1998) reported similar results in an update for lung cancer among this same population of women with non-occupational exposure to chrysotile asbes tos in the Quebec chrysotile mining towns. Their study indicates that the U.S. Environmental Protection Agency overestimates the potency of chrysotile asbestos to increase lung cancer risk by a factor of at least 10. A major breakthrough in bringing a new understanding of the relative health risks of asbestos to a scientific, political, and public audience came from the work of Mossman et al. (1990). Their paper was published in Science at the time when billions of dollars where being spent to remove asbestos from schoolrooms and other buildings in the United States. These authors stated: "clearly the asbestos panic in the U.S. must be curtailed." Their very low risk estimates to children attending classes in schools with asbestos-containing material were reviewed in detail by HEI.AR (1991) and Wilson et al. (1994). Data given in these references show that the average concentration of asbestos measured in 219 American schools is 0.00022 f/ml. Using this average fiber concentration and the most pessimistic methods (or worst case scenario) for calculating risk, the risk for residing in the classroom six hours a day, five days a week for 14 years is one excess cancer death per million lifetimes (Ross, 1995, table 1). SOME OF THE IMPORTANT OCCURRENCES OF ASBESTOS IN OPHIOLITE COMPLEXES AND ASSOCIATED SERPENTINITES In this review, we use a broad definition of the term ophiolite to include those rocks that at least in part are pieces of oce anic crust that have been obducted onto the edges of continental plates. The idealized ophiolite, from the base upward, includes: (1) layered cumulates or mantle sequence comprising tectonized dunites, lherzolites, and harzburgites; (2) gabbros; (3) sheeted diabase dikes; (4) pillow basalts; and (5) various marine sedi ments. The Troodos ophiolite of Cyprus (Robinson and Malpas, 1990) and the Semail ophiolite of Oman (Vetter and Stakes, 1990) are two of the best examples of places where complete or nearly complete sequences of these five rock types are exposed; however, not all of these rock types can be observed in outcrop in many of the ophiolite occurrences, including some of the important serpentinite belts of the world. O'Hanley (1996) gives a very comprehensive review of serpentine mineralogy and the petrology and geology of serpentinites. Not included in this review are the chrysotile-bearing serpentinites of various greenstone terranes, for example, the Abitibi greenstone belt of Ontario, Canada, and the Barberton greenstone belt of South Africa, because characteristic ophiolite assemblages are not observed (O'Hanley, 1996, p. 217). Also not included in this discussion are the carbonate-hosted chryso tile deposits, such as those found in the Barberton-Caroline District and near Kanye, South Africa; in the Laiyuan district, Hepeh Province, China; and in Gila County, Arizona, USA. Anthophyllite Asbestos Deposit in Finland Significant commercial production of anthophyllite asbes tos has occurred only in the north Karelian mountains of eastern 460 M. Ross and R.P. Nolan tos. The tremolite asbestos was quarried in the nearby mountains by the male population for local use and for sale elsewhere. Women then ground the asbestos ore into a powder and mixed the powder with water to form a slurry for application to build ings. This process was repeated every year; consequently the homeowners were repeatedly exposed to tremolite asbestos dusts from an early age. We note that these five "asbestos" villages are located within or a few kilometers from the Guleman and Killan Group ophiolites that form part of the Maden Complex. Aktas and Robertson (1990) describe the Killan Group as consisting of serpentinized peridotite, gabbro, dolerite, basic pillow lava, and pelagic sediments. These observations strongly suggest that the tremolite asbestos was quarried within one or more of the rock units within these complexes. Ankara Ophiolite, Turkey Figure 7. Transmission electron photomicrograph of tremolite asbes tos from Akapnov Forest, Cyprus. Guleman and Killan Group Ophiolites within the Maden Complex, Turkey Yazicioglu et al. (1980) reported on 41 patients having respiratory cancer that were admitted to the Diyarbakir Chest Hospital, Diyarbakir, Turkey, from 1977 to 1978. Of these 41 cases, 23 and 18 were cancers of mesothelial tissue and lung, respectively. Of these, 22 of the mesothelioma and 11 lung can cer cases came from the "asbestos" villages of Cermik, Ergani, Cungus, Maden, and Siverek, whereas one mesothelioma and seven lung cancer cases came from the "non-asbestos" vil lages of Lice, Kulp, Dicle, Hani, Silvan, Harzo, and Cinar. The extraordinarily high incidence of mesothelioma among both genders in the five "asbestos" villages of very low population strongly suggested that the villagers were exposed to asbestos environmentally. It was discovered that tremolite asbestos was used locally to make a whitewash or stucco for the walls, floors, and roofs of houses. The whitewash contained fibrous tremolite and the nonfibrous minerals talc, chlorite, antigorite, and lizardite. Although occasional chrysotile fibers were found in the environment, Yazicioglu et al. (1980) attributed these mesothelioma cases occur ring in the Cermik village region to exposure to tremolite asbes Apparent asbestos-like diseases of the chest, including mesothelioma, have also been reported in the small Anato lian Village of Caparkayi in the Sabanozu area of the Cankiri district, Turkey (Baris et al., 1988a, 1988b). Four cases of pleural mesothelioma were reported in a population of 425 over a three-year period. All of the tumors occurred in women between 26 and 40 years of age. The non-occupational nature of exposure is indicated by the tumors occurring at a young age and in women. Although there is no asbestos mine near this village, the villagers commonly used white stucco described by Baris et al. (1988b, p. 838, fig. 2) as "rich in tremolite asbestos including some very fine fiber." The Baris report indicates that the high incidence of mesothelioma and some of the lung and pleural tissue abnormalities in the village are associated with exposure to tremolite fibers. The villages of Sabanozu and Cankiri lie a few kilometers west and east, respectively, of the Eldiven Dagi, a mountainous area that lies within the Ankara ophiolite melange belt of northern Anatolia (Tankut and Gor ton, 1990, fig. 1). We suggest that the residents of Caparkayi, and probably residents of nearby villages, obtained the stucco ingredients from veins of tremolite asbestos occurring within the Ankara ophiolite complex. Pindos Ophiolite, Greece Six out of the seven reported deaths (3 males and 4 females) from malignant pleural mesothelioma occurred among resi dents of the villages of Milea, Metsovo, Anilio, and Votonosi. These villages are located in the Pindos mountain region of northwestern Greece. Of the 268 people who underwent Xray examination, 46% showed some pleural change, including bilateral pleural plaques, pleural thickening, and restrictive lung function. These lung changes and the mesothelial cancers constitute the cluster of disease referred to as "Metsovo lung" (Constantopoulos et al., 1985, 1987; Langer et al., 1987). Biopsy of the lung tissue in the mesothelioma cases, as well as others with pleural disease, contained tremolite asbestos fibers. Also, History ofasbestos discovery and use 469 sol Forest Complex: in Malpas, J., Moores, E.M., Panayiotou, A. and Xenophontos, C., eds., Ophiolites, Oceanic Crustal Analogues: Proceed ings of the Symposium "Troodos 1987," Geological Survey Department, Nicosia, Cyprus, p. 75-85. Meurman, L.O., Kiviluoto, R., and Hakama, M. 1974, Mortality and morbidity among the working population of anthophyllite asbestos miners in Fin land: British Journal of Industrial Medicine, v. 31, p. 105-112. Mossman, B.T., Bignon, J., Corn, M., Seaton, A., and Gee, J.B.L., 1990, Asbes tos--scientific developments and implications for public policy: Science, v. 247, p. 294-301. Mumpton, F.A., and Thompson, C.S., 1975, The mineralogy and origin of the Coalinga asbestos deposit: Clays and Clay Minerals, v. 23, p. 131-143. Murray, R., 1990, Asbestos: A chronology of its origins and health effects: Brit ish Journal of Industrial Medicine, v. 47, p. 361-365. Newhouse, M.L., and Sullivan, K.R., 1989, A mortality study of workers manufacturing friction materials: 1941-86: British Journal of Industrial Medicine, v. 46, p. 176-179. Nolan, R.P., and Langer, A.M., 2001, Concentration and type of asbestos fibers in the air inside buildings, in Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., The Health Effects of Chrysotile-Asbestos: Contribution of Science to Risk-Management Decisions: The Canadian Mineralogist, Special Publication 5, Ottawa, Canada, p. 39-51. Nolan, R.P., Langer, A.M., and Wilson, R., 1999, A risk assessment for expo sure to grunerite asbestos (amosite) in an iron ore mine: Proceedings of the National Academy of Sciences, v. 96, p. 3412-3419. Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., 2001, Health Effects of Chrysotile-Asbestos: Contribution of Science to Risk Management Decisions: The Canadian Mineralogist Special Publication 5, Ottawa, Canada, p. 1-304. Noro, L., 1968, Occupational and non-occupational asbestosis in Finland: American Industrial Hygiene Association Journal, v. 29, p. 53-59. O.E.D., 1933, The Oxford English Dictionary, v. 1 (A-B), Oxford University Press, Oxford, 1240 p. Ohlson, C.G., and Hogstedt, C., 1985, Lung cancer among asbestos cement workers. A Swedish cohort study and a review: British Journal of Indus trial Medicine, v. 42, p. 397-402. O'Hanley, D.S., 1996, Serpentinites-Records of tectonic and petrological his tory: Oxford University Press, New York, N.Y., 277 p. Petrov, V.P., and Znamensky, V.S., 1981, Asbestos deposits in the USSR: in Riordon, P.H., ed., Geology of asbestos deposits: Society of Mining, Met allurgical, and Petroleum Engineers, Inc., New York, N.Y., p. 45-52. Rackham, H., 1961, Pliny Natural History with an English translation in ten volumes, v. 5, (Books 17-19): Harvard University Press, Cambridge, MA, 544 p. Rassios, A., and Smith, A.G., 2000, Constraints on the formation and emplacement age of western Greek ophiolites (Vourinos, Pindos, and Othris) inferred from deformation structures in peridotites: in Dilek, Y., Moores, E.M., Elthon, D., and Nicolas, A., eds., Ophiolites and Oceanic Crust: New insights from field studies and the ocean drilling program: Boulder, Colorado, Geological Society of America Special Paper 359, p. 473-483. Rey, F., Boutin, C., Steinbauer, J., Viallat, J.R., Allessandroni, P., Jutisz, P., Di Giambattista, D., Billon-Galland, M.A., Hereng, P., Dumortier, P., and De Vuyst, P., 1993, Environmental pleural plaques in an asbestos exposed population of northeast Corsica: European Respiratory Journal, v. 6, p. 978-982. Rey, F., Boutin, C., Viallat, J.R., Steinbauer, J., Allessandroni, P., Jutisz, P., Di Giambattista, D., Billon-Galland, M.A., Hereng, P., Dumortier, P., and De Vuyst, P., 1994, Environmental asbestotic pleural plaques in north east Corsica: Correlation with airborne and pleural mineralogic analysis: Environmental Health Perspectives, v. 102 (supplement 5), p. 251-252. Robinson, P.T., and Malpas, J.,1990, The Troodos ophiolite of Cyprus: New perspectives on its origin and emplacement, in Malpas, J., Moores, E.M., Panayiotou, A., and Xenophontos, C., eds., Ophiolites, Oceanic Crustal Analogues: Proceedings of the Symposium "Troodos 1987," The Geo logical Survey Department, Nicosia, Cyprus, p. 13-26. Rohl, A.N., Langer, A.M., and Selikoff, I.J., 1977, Environmental asbestos pollution related to use of quarried serpentine rock: Science, v. 196, p. 1319-1322. Rom, W.N., Hammar, S.P., Rusch, V., Dodson, R., and Hoffman, S., 2001, Malignant mesothelioma from neighborhood exposure to anthophyllite asbestos: American Journal of Industrial Medicine, v. 40, p. 211-214. Ross, M., 1981, The geologic occurrences and health hazards of amphibole and serpentine asbestos: in Veblen, D.R., ed., Amphiboles and other Hydrous Pyriboles-Mineralogy, v. 9A, Mineralogical Society of America, Wash ington D.C., p. 279-323. Ross, M., 1984, A survey of asbestos-related disease in trades and mining occu pations and factory and mining communities as a means of predicting health risks of nonoccupational exposure to fibrous minerals: in Levadie, B., ed., Definitions for Asbestos and Other Health-related Silicates, ASTM STP 834, American Society for Testing Materials, Philadelphia, Pennsylvania, p. 51-104. Ross, M., 1994, The New Idria serpentinite of California: a toxic rock?: Geo logical Society of America Abstracts with Programs, v. 26., No. 7, 1994 Annual Meeting, Seattle, Washington, October 24-27, p. A320. Ross, M., 1995, The schoolroom asbestos abatement program: a public policy debacle: Environmental Geology, v. 26, p. 182-188. Ross, M., and Virta, R.L., 2001, Occurrence, production and uses of asbestos: in Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., The Health Effects of Chrysotile Asbestos: Contribution of Science to Risk Management Decisions: The Canadian Mineralogist Special Pub lication 5, Ottawa, Canada, p. 79-88. Saracci, R., Simonato, L., Baris, Y., Artvinli, M., and Skidmore, J., 1982, The age-mortality curve of endemic pleural mesothelioma in Karain, central Turkey: British Journal of Cancer, v. 45, p. 147-149. Seiler, H.E., 1928, A case of pneumoconiosis. Result ofthe inhalation of asbes tos dust: British Medical Journal, v.2, p.982. Shcherbakov, S.V., Kashansky, S., Domnin, S.G., Koggan, F.M., Kozlov, V., Kochelayev, V.A., and Nolan, R.P., 2001, The health effects of mining and milling chrysotile: the Russian experience: in Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., The health effects of chrysotile asbestos: Contribution of Science to Risk Management Decisions: The Cana dian Mineralogist Special Publication 5, Ottawa, Canada, p. 187-198. Siemiatycki, J., 1982, Mortality in the general population in asbestos mining areas: In Proceedings of the World Symposium on Asbestos, May 24-27, 1982, Canadian Asbestos Information Centre, Montreal, Canada, p. 337-348. Silvestri, S., Magnani, C., Calisti, R., Bruno, C., 2001, The experience of the Balangero chrysotile asbestos mine in Italy: Health effects among work ers mining and milling asbestos and the health experience of persons living nearby: In Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., The health effects of chrysotile asbestos: Contribution of Science to Risk Management Decisions: The Canadian Mineralogist Special Publication 5, Ottawa, Canada, p. 177-186. Simonen, A., 1980, The Precambrian in Finland: Geological Survey of Finland, Bulletin no. 304, 58 p. Skarpelis, N., and Dabitzias, S., 1987, The chrysotile deposit of Zidani, north ern Greece: Ofiolliti, v. 12, p. 403^10. Skinner, H.C.W., Ross, M., and Frondel, C., 1988, Asbestos and Other Fibrous Minerals: Oxford University Press, New York, N.Y., 204 p. Spadea, P., and Scarrow, J.H., 2000, Early Devonian boninites from the Mag nitogorsk arc, southern Urals (Russia): Implications for early develop ment of a collisional orogen: in Dilek, Y., Moores, E.M., Elthon, D., and Nicolas, A., eds., Ophiolites and Oceanic Crust: New insights from field studies and the ocean drilling program: Boulder, Colorado, Geological Society of America Special Paper 359, p. 461-472. Tankut, A., and Gorton, M.P., 1990, Geochemistry of a mafic-ultramafic body in the Ankara melange, Anatolia, Turkey: Evidence for a fragment of ocean lithosphere: in Malpas, J., Moores, E.M., Panayiotou, A. and Xenophontos, C., eds., Ophiolites, Oceanic Crustal Analogues: Proceed ings of the Symposium "Troodos 1987," Geological Survey Department, Nicosia, Cyprus, p. 339-349. Thayer, B., 2002, Pliny the Elder: the Natural History, Books 1-37 (in Latin): http://www.ku.edu/history/index/europe/ancient_rome/E7Roman/Texts/ Pliny_the_Elder/home.html). Thomas, H.F., Benjamin, I.T., Elwood, P.C., and Sweetman, P.M., 1982, Further follow-up of workers from an asbestos cement factory: British Journal of Industrial Medicine, v. 39, p. 273-276. Timbrell, V., 1989, Review ofthe significance of fiber size in fibre-related lung disease: A centrifuge cell for preparing accurate microscope evaluation specimens from slurries used in inoculation studies: Annals of Occupa tional Hygiene, v. 33, p. 483-505. Timbrell, V., Griffiths, D.M., and Pooley, F.D., 1971, Possible biological impor tance of fiber diameters of South African amphiboles: Nature, London, v. 232, p. 55-56.