1 Chrysotile Asbestos: Economic Benefit with Disregard to Health Dr. Richard A. Lemen To the Canadian Auto Workers Family Education Centre Port Elgin, Ontario September 27, 2008
2 The Chrysotile Lobby Say Chrysotile is Safe And they keep the Evidence Behind Closed Doors Only letting Out What They Spin To Their Favor
3 I Say: Open the Door and Come On IN Let Us See The Evidence
4 Discovery of Chrysotile In Canada DEPOSITS OF CHRYSOTILE were noted in the Eastern Township region of Quebec in Chrysotile asbestos was discovered in Quebec, Canada in The mining of these chrysotile deposits started in 1878, with 50 tons being produced during the mine s first year of operation. Two Regions: Thetford-mines and Asbestos were the areas of commercial exploration.
6 Geologist Geologist Geologist Geologist in in in in Training Training Training Training QAMA QAMA QAMA QAMA
7 Main Asbestos Fiber Types of Commercial Importance % of all asbestos 5% of all asbestos consumed Chrysotile - White fine, silky, flexible Amosite - Brown straight, brittle fibers Crocidolite- Blue & straight Anthophyllite brittle, white fibers Tremolite and Actinolite, Anthophyllite is found mainly as a contaminant in other minerals.
8 Asbestos Fiber Shapes Header Goes Here Fiber Shapes Ultrastructure Rock Formation sheet silicate Serpentine curved fiber with central hollow capillary (eg, chrysotile) Amphibole 23 straight and solid double panes of tetrahedra (eg, anthophyllite, amosite and crocidolite) Fiber Types Origin mined in Canada, Zimbabwe, Swaziland, Russia mined in South Africa (amosite, crocidolite) and Finland (anthophyllite) Usage 95% of all US asbestos 5% of all US asbestos 8
9 Chrysotile Asbestos Veins of chrysotile
10 ASBESTOS USES CHRYSOTILE ASBESTOS FIBERS SEPERATING FROM THE MINERAL Acoustical Plaster
11 Early Health Findings 1898, 1906, 1908 Britain, France, Italy Report severe and fatal respiratory disease in asbestos workers 1912 Canadian Department of Labour denied health effects to Quebec s millers and miners Caulk
12 1930 McGill University Metropolitan Life Assurance Co. who sponsors the Dept. of Industrial Hygiene at McGill was told by the Clinical Director that no abnormalities of significance found and no cases of pneumoconiosis from asbestos in Canada Metropolitan s own records found claims from Thetford mines in 1935, preponderance from lung disorders Drywall From: Greenberg, 2008 & Fitzhugh, 1935 in Castleman, 1996.
13 Asbestos Becomes a Major Market Electrical uses
14 SCIENTISTS, ALCHEMISTS OR THE DEVIL S DOCTORS?
15 CHRYSOTYLE PRODUCERS Create Doubt Chrysotile Asbestos Obscure the Facts
16 Quebec Johns-Manville Medical Officer denies validity of the world literature over the past 40 years showing serious human health effects from asbestos Even though his study reported in those employed >10 years : 17 early asbestosis; 5 moderate asbestosis; 0 advanced asbestosis dismissed these radiological findings as irrelevant because without case history & physical examination no diagnosis is made Ebony Board in Laboratories Concluded no case of asbestosis found From: Greenberg, 2008
17 Quebec Wives of 75 Miners On May 7th, 75 miners wife's attended the local council meeting, addressing it to tackle their husbands health problems A counselor promised to submit a resolution to the Quebec Asbestos Association, the Provincial Dept. of Health, the County Bureau of Hygiene & Philip Carey Manufacturing Company The resolution was never pursued and the wives were brushed off with uninformative official communications From: Greenberg, 2008 Asbestos FFFF llll oor iiii ng
18 Fi rrrr epr oofi ng Thetford Medical textbook by RT Johnstone reports even though millworkers in Thetford were heavily exposed to fine asbestos dust, their medical officer states they do not suffer from asbestosis. From: Greenberg, 2008
19 East Broughton, Quebec Mr. LaDoux, a local newspaper man, reported that the hazards of asbestos had been well known in N. American mining for the proceeding 15 years. He also stated that the high tuberculosis rates may be due to misdiagnosis when in fact they may be due to asbestosis Fire Door Core Both Canadian Medical Association and the government said he was wrong and still do so today From: Greenberg, 2008
20 Quebec two cases of pleural mesothelioma, one with minimal asbestosis and the other with no asbestosis, among 4,000 asbestos workers : seen at the Mesothelioma Thetford International Clinic in Quebec, Canada where Canadian asbestos miners were seen. [Cartier P, Abstract of discussion. Arch Ind Hyg Occup Med: 5; 262]. Ga ske ts
21 Quebec, 1955 Cartier also reported 128 with asbestosis Asbestos Packing's From Cartier P, Some clinical observations of asbestosis in miners and mill workers. Arch Indust Health. 11:
22 , 1955 Quebec BBBB uuuu iiii llll dddd iiii nnnn g g g g SSSS iiii dddd iiii nnnn gggg While making no statement on these current findings which his predecessors had maintained the miners to be superlatively fit over the years Dr. Cartier stated:... More frequently it [asbestosis] remains a disease which can be tolerated quite well for many years... this disease may look more serious and cause important medicolegal problems if a too scientific medical concept [sic] or a too liberal social interpretation is accepted by medicolegal professions, labor and compensation bodies. From Cartier P, Some clinical observations of asbestosis in miners and mill workers. Arch Indust Health. 11: & Greenberg, 2008
23 Insulation in appliance Thetford medical officer informs a visiting British industry physician that he had observed 126 workers with pleural plaques and that 93% of them had signs of asbestosis. The communication was kept confidential From Greenberg M, The art of perpetuating a public health hazard. JOEM. 47 (2), February as taken from Knox JF, Thetford
24 Thetford Rossiter reported a high prevalence of various abnormal radiological changes among miners and millers from Thetford- Mines. Light Fixtures Gibbs found a markedly higher prevalence of pleural calcification among workers from Thetford- Mines than from the Asbestos region. From: Ataollah N, Dufresne A, Case B, Vali H, Williams- Jones AE, Martin R, Normand C, Clark J, Lung Mineral Fibers of Former Miners and Millers from Thetford- Mines and Asbestos Regions: A Comparative Study of Fiber Concentration and Dimension Archives of Environmental Health, Jan. The finest branches of the airway, the respiratory bronchioles, and the alveolar sacs which are involved in gas exchange. The inhalation of irritant fibers of asbestos sets up inflammation which may cause impairment of uptake of oxygen, and can lead eventually to respiratory failure.
25 1980 Quebec Results of an epidemiological study of an birth cohort of Quebec chrysotile employees of both mining regions were published. Among men employed between 1926 and 1975, an excess mortality of 2% for the Asbestos region and 10% for Thetford-Mines was found. Laboratory equipment From: Lung Mineral Fibers of Former Miners and Millers from Thetford-Mines and Asbestos Regions: A Comparative Study of Fiber Concentration and Dimension Archives of Environmental Health, Jan, 2001 by Ataollah Nayebzadeh, Andre Dufresne, Bruce Case, Hojatolah Vali, A.E. Williams-Jones, Robert Martin, Charles Normand, James Clark
26 1993 Quebec In a follow-up of the original study the SMR for lung cancer was higher among workers at Thetford-Mines (1.89) than among workers from Asbestos region (1.55) for cumulative exposures that exceeded 100 million particles per cubic fiber x year (mpcf/y). Mastics and Adhesives From: Ataollah N, Dufresne A, Case B, Vali H, Williams-Jones AE, Martin R, Normand C, Clark J, Lung Mineral Fibers of Former Miners and Millers from Thetford-Mines and Asbestos Regions: A Comparative Study of Fiber Concentration and Dimension Archives of Environmental Health, Jan.
27 The Idea Sent the Alchemist again back to the lab to find why these increases were occurring
28 THE ALCHEMIST WENT TO THE LITERATURE Chrysotile bio-persistence in the lung Chrysotile Asbestos migration Mesotheliomas and chrysotile The significance of low-level amphibole exposures in predominantly chrysotile mixes was not appreciated until studies of fibres in lungs using electron microscopy showed the high lung burden of amphibole fibres in the 1970s and 1980s. Elmes P, Mesotheliomas and chrysotile. Ann Occup Hyg. Aug;38(4):547-53, 415. Behold Novelty products It s TREMOLITE NOT CHRYSOTILE
29 Tremolite not Chrysotile Reviewing the current evidence published and unpublished, it seems likely that chrysotile uncontaminated by tremolite may not have caused any mesotheliomas even at high cumulative life-time exposures. Asbestos Siding for Houses From: Elmes P,, Mesotheliomas and chrysotile. Ann Occup Hyg. Aug;38(4):547-53, 53, 415.
30 OOPS!!!! Roofing Materials Mixed Exposures to Chrysotile and Amphiboles Begin, et al. noted that although exposure to tremolite may be as much as 7.5 times higher in Thetford than in the city of Asbestos, the incidence of mesothelioma in these two Quebec mining towns was proportional to the size of their work forces. Stayner, Dankovic, Lemen, Occupational Exposure to Chrysotile Asbestos and Cancer Risk: A Review of the Amphibole Hypothesis, Am. J. Pub. Health 86:
31 specificity of this conclusion, have shown that amphibole fibres also differ from chrysotile in being far more durable and bio-persistent in lung tissue lung lung burden burden analyses, analyses while adding to the Fate of Chrysotile Epidemiological research during the past 40 years has demonstrated with increasing clarity that amphibole asbestos fibres--crocidolite, amosite and tremolite--are more carcinogenic than chrysotile. Stair Covering McDonald JC, Mineral fibre persistence and carcinogenicity. Ind Health. Oct;36(4): A smaller number of well-controlled studies using
32 Bio-persistence Crocidolite is much more bio-persistent than chrysotile (half-time of several years). Tremolite present in the patients [lungs] with mesothelioma raise the possibility that these fibers may be important in the pathogenesis of the tumors. Berry G, Models for mesothelioma incidence following exposure to fibers in terms of timing and duration of exposure and the biopersistence of the fibers. Inhal Toxicol. Feb;11(2): Churg A, Wiggs B, Depaoli L, Kampe B, Stevens B.,1984. Lung asbestos content in chrysotile workers with mesothelioma. : Am Rev Respir Dis. Dec;130(6):1042-5
33 Mesothelioma develops in the two layers of the pleura But Where Does Mesothelioma Occur Remaining Lung Tumor then spreads to covers the lung in a thick sack that squeezes and suffocates as it grows
34 Where Does Mesothelioma Occur
35 Chrysotile Leaves the Lung By 12 months post exposure, 99.92% of all the remaining chrysotile was less than 5 micron in length. The long tremolite fibers, once deposited in the lung, remain over the rat's lifetime with essentially an infinite half-time. Even the shorter fibers, following early clearance, also remain with no dissolution or further removal. Bernstein DM, Chevalier J, Smith P., Comparison of Calidria chrysotile asbestos to pure tremolite: final results of the inhalation biopersistence and histopathology examination following short-term exposure. Inhal Toxicol. Aug;17(9):
36 The Pathogenesis of Asbestos-Associated Disease Header Goes Here June 17, 1982 John E. Craighead, M.D., and Brooke T. Mossman, PhD. Much current debate centers around the question of whether all types of asbestos possess the capacity to induce mesothelioma. Experiments in animals yield an affirmative answer 73 Fiber Types 36
37 Asbestos and Its Diseases 2008 Header Goes Here John E. Craighead, M.D., and Allen R. Gibbs 73Overall, this book is a rich source of historical facts and studies on asbestos and its diseases, yet highly personalized with strong individual viewpoints. viewpoints. It is less authoritative as a source for risk assessment and litigation issues. New England Journal of Medicine: Book Reviews, Alex Burdorf, Burdorf, July 31, Fiber Types 37
38 2008 Chapter 4. Epidemiology and Risk Assessment Header Goes Here Graham W. Gibbs and Geoffrey Berry ` EPIDEMIOLOGY AND RISK ASSESSMENT 107 replaced by acetone clearing. When modern quality control methods and sample density rules were introduced, the fiber concentration became 3200 f/ml. Host and Environmental Considerations The third category of parameter influencing risk estimates includes smoking, as well as other host and environmental variables. Selikoff et al. (1968) first reported a synergis-tic effect between asbestos and smoking in the causation of LC, and this observation was confirmed by Berry et al. (1972). In a later follow-up Berry et al. (1985) found that "overall nonsmokers have a RR of LC due to asbestos exposure 1.8 times that of smokers." More recently, Liddell (2001a) concluded, "the RR of LC from asbestos exposure is about twice as high in nonsmokers as in smokers." His conclusion was not without controversy since in another review, Lee (2001) stated, "asbestos exposure multiplies risk of LC by a similar factor in nonsmokers and smokers." The work of Liddell (2001a) was extended by Berry and Liddell (2004) who concluded, "The excess RR for LC from asbestos exposure is about three times higher in nonsmokers than in smokers," and "If interactions are pres-ent the RR from exposure changes only slightly between light and heavy smokers, but is higher (in the former than the latter). The RR estimated from epidemiological studies of a mixed population of nonsmokers and smokers applies to smokers." In some areas, radon in homes is elevated. While debated, radon and radon daughters are now established carcinogens (Darby et ai., 1998). This factor has not been generally taken into account in asbestos risk estimations. The effect of not taking confounding, or modifying factors into account could lead to either an underestimation or an overestimation of the risk ascribed to asbestos, but an overestimation of risk is more likely, since in practice coexposures tend to correlate positively. Even the asbestos scientists That Negate the Role of Chrysotile Have to Admit: 73 _ Thresholds of Risk There are levels of exposure below which asbestosis resulting from exposure does not occur, but estimates of thresholds differ. It is debated whether there is a threshold below which there is no increase in risk of LC and MM (Browne and Gibbs, 1998). A lin-ear dose-response relationship between RR and exposure is often used as "a widely accepted and scientifically reasonable compromise rather than an established scientific principle" (HEI-AR, 1991). Hodgson and Darnton (2000) noted that "direct statistical confirmation of a threshold from human data is virtually impossible," and used a non-threshold model. Browne (2001) criticized these authors, while Liddell (2001b), noted, "nonlinearity is extremely difficult to detect epidemiologically, especially at low levels of exposure." While it might seem prudent for regulators to assume a linear risk through zero in the absence of proven evidence, it is argued that such an assumption is contrary to what is known about the interaction of asbestos with the respiratory tract. For example, not all fibers in the air are inhaled or penetrate into the lung. It is necessary for fibers to get to the pleura to cause disease, some fibers dissolve and are eliminated and the majority deposit proximally in the respiratory tract. Fibers are coated by biological fluids that may serve to protect the lung. There are DNA repair mechanisms that provide protection in the event genetic damage occurs. Taken together, it is highly improbable that there is a finite risk at close to zero exposure and it seems reasonable to conclude that thresholds exist. Fiber Types It is necessary for fibers to get to the pleura to cause disease... 38
39 Where Does the Chrysotile Go? Fibers translocation is a slow process developing over decades of life: it is aided by high biopersistence, by inflammation-induced induced increase in permeability, it is hindered by fibrosis that increases interstitial flow resistances. Miserocchi G, Sancini G, Mantegazza F, Chiappino G, Translocation pathways for inhaled asbestos fibers. Environ Health. Jan 24;7:4. In lung, amosite fibers were greatest in number followed by chrysotile, crocidolite, tremolite/actinolite, and anthophyllite. In mesothelial tissues, chrysotile fibers were 30.3 times more common than amphiboles. Suzuki Y, Yuen SR Asbestos fibers contributing to the induction of human malignant mesothelioma. Ann N Y Acad Sci. Dec;982:
40 Biologic Plausibility Coherence Hill s Considerations for Determining Causality Strength of Association Consistency of Observed Association Biological Gradient Experimental Analogy As an overall model for determining causality, the considerations espoused by Sir Austin Bradford Hill is well accepted and have been widely used by epidemiologists. Accordingly, as Hill noted, None of my nine view points can bring indisputable evidence for or against the cause-and-effect hypothesis, and none can be required as a sine qua non. Specificity of the Association Temporality
41 Biological Plausibility It is not the chemical composition, of asbestos fibers alone, that is important in their ability to produce disease. The health effects of asbestos are related primarily to their morphology, shape and size. Many researchers contend that the potency of crocidolite is related to its thin diameter (Stanton & Wrench, 1972) (Stanton, et al, 1981). Similarly, inhaled chrysotile fibers have a tendency to split longitudinally and partially dissolve creating short fibrils of the thin fibers in the lung (Dement & Brown, 1993) (Sebastien et al, 1989). The consensus view is that chrysotile asbestos is carcinogenic and capable of causing or contributing to the development of lung cancer (IPCS, 1998) (IARC 1977)
42 Biological Plausibility Mesotheliomas develop in the pleura, peritoneum and other mesothelial cells (Galateau-Sallé F, 2006 ). Chrysotile is a cause of cancer in the lung and chrysotile migrates to the mesothelial linings of the body (Suzuki & Kolynema, 1991) (Kolyema & Suzuki, 1991) (Sebastien, et al, 1980). Plausibility Studies indicate that chrysotile penetrates individual cells, enters the nucleus and induces abnormal chromosome formations in dividing cells (Malami, et al, 1990) Some of the abnormalities include the deletion of the P53 gene growth (Leversse, et al, 1997)
43 Coherence Coherence asks if the causal theory is not inconsistent with what is already known of the injury or disease. It is universally accepted that chrysotile reaches the pleura and causes injury in the pleura (pleural plaques / pleural thickening) It is universally accepted that chrysotile is carcinogenic There is no biologic argument that explains why chrysotile is incapable of causing mesothelioma.
44 Strength of Association Strength of Association is a reflection of the strength of effect in a given study. When evaluating the issue of chrysotile asbestos and its risk of inducing mesothelioma it is important to note: Mesothelioma is rare if not non-existent among the population of people not exposed to asbestos.
45 Strength of Association The rarity of the disease, coupled with the lack of mortality rates in the populations used as controls and problems in diagnosis and reporting, make the assessment of the actual risk for mesothelioma through the means of epidemiologic studies difficult (EHC 203). Although no background incidence of mesothelioma has been firmly established, it is estimated that it occurs probably on the order of 1 case per 1,000,000 persons per year or less (Hillderdal, 1999)
46 Is there a dose-response relationship between chrysotile and disease? Like other forms of asbestos, there is an increased risk of mesothelioma with increasing exposure to chrysotile. (See, Rogers et al, 1991) Biological Gradient
47 Consistency In the German Federal State of Saxony-Anhalt, Strum and his colleagues reviewed 843 cases of proven asbestos-accepted mesotheliomas and determined that 67 of the cases were related to exposure to only chrysotile asbestos. Strum, W. et al. Use of asbestos, health risks and induced occupational diseases in the former East Germany. Toxicology letters 72 (1994)
48 Consistency Chrysotile miners in Canada (Cartier 1952) Chryotile miners in Italy (Piolatto( 1990) Chrysotile miners in Zimbabwe (Cullen and Baloyi 1991) (Baloyi( 1989) Asbestos cement workers in Louisiana (Hughes 1986) Textile workers in New Jersey (Borrow 1973) Friction product manufacturing in Connecticut (Teta( 1983) Friction product manufacturing in England (Newhouse & Sullivan 1989) Friction product manufacturing in Germany (Konetzke( 1981)
49 Consistency Mechanics who installed brake linings in Canada (McDonald 1970) Mechanics in the United States (Langer 1982) (Kagan 1983) (Huncharek 1989) Mechanics who installed brake linings in Australia (Leigh & Driscoll 2003) Textile workers in North Carolina (Dement 1983) (Robinson 1979) Railroad workers using chrysotile insulation in Italy (Malsoni 1991) Railroad workers using chrysotile insulation in Finland (Nokso-Kovisto 1994) Railroad workers using chrysotile insulation in the United States (Mancuso 1988) Wives of textile and friction workers in New York (Vienna & Polen 1985)
50 Consistency Mechanics who installed brake linings in England (Greenberg 1974) Railroad workers using chrysotile insulation in Switzerland (Rattuner( 1991) Mechanics who installed brake linings in Denmark (Hansen 1989) Italian worker in the wine filter industry (Scansetti( 1984)
51 Chrysotile with no Contamination AUTHOR, YEAR COHORT STUDIES Piolatto (1990) Silvestri (2001) Mirabelli et al(2008) Yano (2001) Xiaorong (2005) Cullen & Bayoli (1991) Kogan (1986) Observed / Expected 2 v v v v v v v v Relative Risk / Odds Ratio P-Value (95% CI) Alleged Contaminant Balangeroite Tremolite Anthophyllite None 14 cases have now occurred among the entire work force and 13 cases among persons exposed outside the workplace to Balangero chrysotile.
52 Chrysotile AUTHOR, YEAR Population Studied Observed / Expected Relative Risk 95% CI Begin (1992) Thetford & Asbestos 49 v Camus (1998) Women Thetford Mining Area 7 v Raffn et al (1993) Asbestos Cement Workers >20 Years Robinson (1979) Textile, Friction & Packing Workers 17 (males) 4 (females) (SMR) (SMR)
53 Simson reported fibrosis and golden yellow bodies in the lungs of guninea-pigs similar to those found in humans. The animals were exposed 2 hours per day for 50 days in 1925 to chrysotile. EARLY EXPERIMENTAL EVIDENCE Simson,, F.W., Pulmonary asbestosis in South Africa [abstract]. Brit Med J, July-Dec., p. 258.
54 EARLY EXPERIMENTAL EVIDENCE From Greenberg M, The art of perpetuating a public health hazard. JOEM. 47 (2), February. As taken from Nordman M, Sorge A. Lungenkrebs durch asbeststraub in Tierversuch. Z. Krebsforsch. 51: A German study of mice exposed to chrysotile containing dust found Hyperplasia and metaphasa of the bronchial epithelium some considered premalignant
55 EXPERIMENTAL EVIDENCE 1963 Effects of chrysotile dust on rat & guinea-pig lungs Seen only in alveolar macrophages Varies in size from 10 microns long to less than 1 micron After some months some of the dust showed structural changes as dissolved by body fluids Blood-air barrier became thicker than normal From: Davis, An electron microscopy study of the effect of asbestos dust on the lung. Br J Exp Path; 44; blood air barrier of a capillary on the wall of an alveole of the lung (rat)
56 EARLY EXPERIMENTAL EVIDENCE Study of chrysotile inhalation on the rat lung Small particle size < 3 microns Rapidly produced fibrotic lesion in the rat lungs Found asbestos is fibrogenic only when it can be ingested by phagocytes From: Holt et al., The early effects of chrysotile asbestos dust on the rat lung. J Path Bact: : 87 (1); 15-23
57 EARLY Experimental Evidence 1964 Chrysotile heated between degrees centigrade showed remarkable toxicity when compare to quartz which lost its cytotoxicity when heated over 500 degrees centigrade Unheated chrysotile and chrysotile heated in other ranges did not exhibit such toxicity The disordered state of chrysotile in the heat treatment may explain the differences in toxicity during the the transformation of chrysotile into fosterite From: Hayashi, Cytotoxicity of heated chrysotile. Env Health Presp: : 9; chrysotile Quartz
58 EARLY Experimental Evidence 1965 Chrysotile effects on the guinea-pig lung First effects after airborne exposure to chrysotile occurred after 14 days with lesions and bronchiolitis After 266 days after first exposure all animals showed widespread fibrosis but few asbestos bodies From: Holt et al., Experimental asbestos with four types of fibers: Importance of small particles. Ann NY Acad of Sci: : 132; 87-97
59 Mesothelioma - Rat Inhalation Zimbabwean Chrysotile 0.6% (1/169) Quebec Chrysotile 4.7% (9/193) Canadian Chrysotile 2.9% (4/137) = Lippman M, Deposition and retention of inhaled fibers: Effects on incidence of lung cancer and mesothelioma. Occ Env Med, 51: = Wagner et al, The effects of the inhalation of asbestos in rats. Br J Ca, 29: In intra pleural inoculation experiments Canadian chrysotile UICC Grade 7 most carcinogenic
60 Experiment Do laboratory experiments support the hypothesis that chrysotile causes mesothelioma? Animal studies show chrysotile causes mesothelioma; Cellular studies show chrysotile kills cells, and alters DNA; Pathology studies show chrysotile is found in the mesothelial tissue of mesothelioma victims
61 Coherence Amosite Crocidolite Chrysotile Cellular Damage x x x Genetic Damage x x x Animal Fibrosis x x x Animal Cancer x x x Animal Mesothelioma x x x Human Asbestosis x x x Human Cancer x x x Human Mesothelioma x x x
62 Neoplasms of rodents and other animals are fundamentally similar in nature, and there are many examples of chemicals that cause tumors in both humans and animals. It is a fundamental principle that in the absence of adequate data on humans, it is biologically plausible and prudent to regard agents and mixtures for which there is sufficient evidence of carcinogenicity in experimental animals as they presented a carcinogenic risk to humans. Wilbourn J., Haroun L., Heseltine E., Kaldor J., Partensky C., Vainio H. Response of experimental animals to human carcinogens: An analysis based on the IARC monographs programme. Carcinogenesis 7: (1986). Rice, J. M., Wilbourn, J. D. Tumors of the nervous system in carcinogenic hazard identification Toxicologic Pathology vol. 28 (1), (2000).
63 Analogy Do similar substances cause similar diseases? Like exposure to chrysotile, exposure to other forms of asbestos: causes asbestosis, lung cancer, and mesothelioma. > 95% of all asbestos Used Amphiboles Amosite - Brown Crocidolite- Blue Anthophyllite chrysotile
64 Hill s Considerations Plausibility Can Chrysotile Cause Mesothelioma? SATISFIED Coherence SATISFIED Strength of Association SATISFIED Consistency SATISFIED Biological Gradient SATISFIED Experimental Evidence SATISFIED Analogy SATISFIED Specificity NOT APPLICABLE Temporality SATISFIED Lemen, 2004
65 Mixed Exposures to Chrysotile and Amphiboles Case Control Study Relative Risk = 1 for no asbestos in lung tissue Relative Risk = 6 for chrysotile Relative Risk = 12 for amphiboles Relative Risk = 61 for chrysotile plus amphiboles Mixtures of fibers are associated with higher relative risks than either type of fiber alone, both when the total quantity of fiber found is low and when it is high. Mixtures of amphiboles and chrysotile occur much more commonly in the lungs of mesothelioma patients relative to controls than do either of the main types of fiber alone. Acheson ED, Gardner MJ, Mesothelioma and exposure to mixtures of chrysotile and amphibole asbestos, Arch Environ Health. 34(4): (1979)
66 As Consumption Goes Up Indicators of Human Exposure go up Ferruginous Bodies Tokyo General Population (5mg wet tissue) % Years Ferruginous Bodies If human indicators, like asbestos bodies increase as consumption increases then so do environmental background levels.
67 Suicide Cor Pulmonale Asbestosis Peritoneal Mesothelioma Larynx Cancer Pleural Mesothelioma Lung Cancer Gastrointestinal Cancers Asbestos Skin Warts Asbestos One Substance Many Diseases
68 Chrysotile Asbestos Hazards Recognized Worldwide Argentina Scotland Poland Italy Latvia Slovenia Gabon Austria Finland Netherlands Luxembourg Germany Denmark Chile Estonia Greece France Switzerland Uruguay Norway Sweden Slovakia Cyprus Wales Spain Malta Ireland Australia England Hungary Iceland Portugal Seychelles Honduras Belgium New Zealand United Arab Emirates Saudi Arabia Czech Republic Northern Ireland South Africa Kuwait Japan (new use) Lithuania Brazil (banned by 4 most industrialized states)
69 Governmental Agencies conclude Chrysotile causes Mesothelioma Surgeon General of the United States WHO EPA World Trade Organization National Academy of Sciences ILO
71 In a profit-driven frenzy, the asbestos alchemists peddle their toxic wares to ill-informed informed governments and consumers. But blow away their smoke, remove their mirrors, and the truth emerges for all to see: All forms of asbestos are deadly, there is no safe concentration of exposure identified, industry propaganda is unreliable and the continued to use of chrysotile is unconscionable. From: Lemen RA, Smoke and Mirrors: Chrysotile asbestos is good for your Illusion and confusion but not fact. In: India s Asbestos Time Bomb, Eds. David Allen and Laurie Kazan-Allen, IBAS, London, September.
17 Mesothelioma and Asbestos Exposure J. Corbett McDonald and Alison McDonald Historical Background It was the Conference on the Biological Effects of Asbestos at the New York Academy of Sciences, organized
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1 Asbestos as a metaphor for teaching risk perception (modified slightly from Gunter, M.E. (1994) Journal of Geological Education, 42, 17-24) ABSTRACT Asbestos -- the word means different things to different
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Home Search Collections Journals About Contact us My IOPscience Heterogeneity of exposure and attribution of mesothelioma: Trends and strategies in two American counties This content has been downloaded
Thorax 1996;51(Suppl 2):S9-S15 S9 Asbestos exposure, asbestosis, and asbestos-attributable lung cancer Robert N Jones, Janet M Hughes, Hans Weill Departments of Medicine and Biostatistics and Epidemiology,
Asbestos Toxicological overview Kinetics and metabolism Key Points Short asbestos fibres are deposited in the upper respiratory tract where they are cleared by mucociliary action Longer fibres are carried