Scientific Publications Retrievals

Under this heading, the ICA wishes to draw your attention to some recent and past scientific publications of interest which may have escaped your scrutiny. This site will be updated periodically.
Updated August 2017

First Identification of Pulmonary Asbestos Fibres in a Spanish Population.

Lung. 2017 Aug 8. doi: 10.1007/s00408-017-0042-1.

Velasco-García MI , Cruz MJ, Diego C, Montero MA, Álvarez-Simón D1, Ferrer J.

This study, first undertaken as a PhD tesis, was undertaken to characterize, for the first time in Spain, the type of asbestos fibres in the lungs of exposed and non-exposed populations.
Lung samples from subjects living in Barcelona and Ferrol, Spain, were studied in three groups: Group A : subjects without known respiratory disease; Group B : ex-shipyard workers and Group C : patients with lung cancer. To identify the type of fibre, the samples were analysed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX).

RESULTS: All the fibres identified corresponded to amphiboles (crocidolite 45%, anthophyllite 22%, tremolite 16%, amosite 15% and actinolite 3%. Forty-six percent of the AF analysed had a length > 5 µm and a diameter < 0.2 µm.

CONCLUSIONS: The authors conclude that the results of this study provide the first data on the type of asbestos retained in the lung of Spanish population. They note a particularly striking finding : the exclusive retention of amphiboles, which suggests that chrysotile is eliminated after inhalation.

Lung function not affecred by asbestos exposure in workers with normal CT scans.

American Journal of Indutrial Medicine, March 30, 2017
DOI 10.1002/ajim.22717

C. Schikowsky C., Felten M, Eisenhawer C., Das M.and Kraus T,

This study by was conducted by specialists of occupational medecine and diagnostic radiology from Germany an the Netherlands.
They investigated the suggestion that asbestos exposure affects lung function, even in the absence of asbestos-related interstitial or pleural risk factors such as cumulative asbestos exposure or emphysema.
They analyzed associations beteween known risk factors such as cumulative asbestos exposure and key lung function parameters in formerly asbestos workers with normal CT scans.

They found that lung function parameters such as FVC (forved vital capacity), airway resistance and other lung function parameters were significantly associated with the burden of smoking, BMI (body mass index) and years from end of exposure. However, they were not affected by factors diectly related to amount and duration of exposure.

The authors conclude that their « results confirm the well-known correlation between lung function, smoking habit and BMI, … but no significant association between lung function and asbestos exposure.

Association Between Laryngeal Cancer and Asbestos Exposure : A Systematic Review

JAMA Otolaryngol Head Neck Surg. doi:10.1001/jamaoto.2016.3421
Published online December 1, 2016

Ashley P, O’Connell Ferster, Jane Schubart, Yesul Kim, David Goldenberg,

Question : Is there a link exists between laryngeal cancer and asbestos exposure. In this publication, the authors update the most recent literature since 2000. Findings : Of the 162 articles screened, 15 articles comprising 438 376 study participants were included. Of these 15 studies, 10 showed no correlation between asbestos exposure and laryngeal cancer. The remaining 5 studies claimed a correlation between asbestos exposure and incidence of laryngeal cancer, although only 1 accounted for smoking or alcohol exposure while 3 others did not, and 1 study included only 2 patients.

Evaluation of asbestos-containing products and released fibers in home appliances

Sung Ho Hwang (National Cancer Center) & Wha Me Park Seoul, South Korea.
Journal of the Air & Waste Management Association

Accepted author version posted online: 04 May 2016, Published online: 04 May 2016
Download citation http://dx.doi.org/10.1080/10962247.2016.1180329.

This study is about asbestos-containing products and released asbestos fibers from home appliances. The authors investigated a total of 414 appliances manufactured between 1986 and 2007. Appliances were divided into three categories: large- and small-sized electric appliances, and household items. Analysis for asbestos-containing material (ACM) was performed using polarized light microscopy (PLM) and stereoscopic microscopy. Air sampling was performed to measure airborne concentration of asbestos using a phase contrast microscope (PCM). The results of the analysis for ACM in appliances show that large-sized electric appliances (refrigerators, washing machines, etc.) and household items (bicycles, motorcycles, gas boilers) contain asbestos material. Small-sized electric appliances do not contain asbestos material. All appliances with detected asbestos material showed typical characteristics of chrysotile (7–50 %) and tremolite (7–10 %). No released fiber concentration of ACM was measured from the tested appliances when the appliances were operating.

Airborne asbestos exposures associated with the installation and removal of roofing products

Lotter J. T. et al
J Occup Environ HYG (2016) Vol 13, Issue 8, 121-131
DOI:10.1080/15459624.2016.1183010

Roofing products are generally considered non-friable and are not expected to release appreciable amounts of airborne asbestos fibers; however, despite the variety of roofing products that have contained asbestos over time, there are no comprehensive analyses of the exposure data associated with these products in the published literature. The objective of this study was to analyze the available data and characterize asbestos exposures associated with the installation, removal, and replacement of built-up roofing (BUR), felts, flashings, shingles, coatings, cements, and mastics under a variety of work practices. Published and unpublished literature that contained the following information was included in the analysis: (1) airborne fiber concentrations determined by PCM; (2) a description of the product(s) used; and (3) a description of the task(s) performed. More than 800 personal air samples from 12 studies performed between 1982 and 2010 were identified which fit the inclusion criteria. The findings indicate that short-term and full-shift exposures from the use of asbestos-containing roofing products were typically well below applicable occupational exposure limits. Additionally, the cumulative exposures associated with roofing work would be well below published chrysotile no-observed-adverse-effect-levels (NOAELs) for asbestos-related diseases.

An Evaluation of Reported No-Effect Chrysotile Asbestos Exposures for Lung Cancer and Mesothelioma

Critical Reviews in Toxicology, 38:191–214, 2008

Jennifer S. Pierce, Meg A. McKinley, Dennis J. Paustenbach, and Brent L. Finley
ChemRisk, Inc., San Francisco, California, USA

Abstract:
Numerous investigators have suggested that there is likely to be a cumulative chrysotile exposure below which there is negligible risk of asbestos-related diseases. However, to date, little research has been conducted to identify an actual “no-observed adverse effect level” (NOAEL) for chrysotile-related lung cancer and mesothelioma. The purpose of this analysis of several publications was to summarize and present all of the cumulative exposure-response data reported for predominantly chrysotile-exposed cohorts in the published literature. The review covered cohorts from A/C manufacturing, friction materials, textiles, mining and milling. A must read.

The authors conclude from their extensive review that « it does seem to indicate that low occupational exposures to chrysotile (e.g.: exposures historically experienced by vehicle mechanics) are unlikely to cause mesothelioma. »

Fiber analysis vignettes: Electron microscopy to the rescue!

Ultrastructural Pathology
Published online at : http://dx.doi.org/10.3109/01913l 23.2016.1149531

Roggli, V. L. (Duke University Medical Center, Durham, NC.)

Abstract:
The author, Dr. Victor Roggli, demonstrates that the use of electron microscopy to analyze the different asbestos fiber types retained in lung tissue is the best tool to attribute relationships with mesothelioma. The relation with commercial amphiboles (amosite and crocidolite) and mesothelioma is verified in a number of asbestos-exposed workers such as in textiles, friction products, auto mechanics, railroad workers, insulators etc. The results show that it is not related to chrysotile, but to the amphibole fiber types, which are retained in the lung far longer compared to chrysotile. The author concludes that he findings by electron microscopy do not support the claims that light and intermittent exposures to chrysotile asbestos are related to mesothelioma, but rather to the high, long and cumulative exposure to commercial amphiboles retained in the lung. TABLE I of this paper is compelling.

Historical ambiant asbestos concentrations in the United States- analysis of published literature (1960-2000s)

Inhalation Toxicology (2015) 27 :754-766
Abelman et al.

Abstract:
This is a comprehensive review and analysis of data describing outdoor concentrations of asbestos. The authors have identified data from the published literature, government reports, and unpublished studies, some of which have never previously been presented.  Their analysis combined 2,058 samples collected in at least 40 U.S. states from 17 published and unpublished studies.

The authors found that the estimated overall mean ambient asbestos concentration for the 1960s through 2000s was 0.00093 f/cc.  The concentration in the 2000s was estimated to be two orders of magnitude lower than in the 1960s-1980s.

Pleural mesothelioma and lung cancer risks in relation to occupational history and asbestos lung burden

Occup Environ Med 2015,0 : 1-10
Gilham C. et al.

Abstract:
This is a population-based study of pleural mesothelioma patients with occupational histories and measured asbestos lung burdens in occupationally exposed workers and in the general population.

The authors indicate that the relationship between lung burden and risk, particularly at environmental exposure levels, will enable furure mesothelioma rates in people born after 1965 who never installed asbestos to be predicted from their asbestos lung burdens.

They indicate that he lifetime mesothelioma risk is approximately 0.02% per 1000 amphibole fibers per gram of dry lung tissue over a more tha 100-fold range, from 1 to 4 in the most heavily exposed building workers to less than 1 in 500 in most of the population.

The measured lung burdens indicated that the asbestos fibers counted were amosite (75%), crocidolite (18%), other amphiboles (5%) and chrysotile (2%). It confirms the major contribution of amosite to UK mesothelioma incidence The authors conclude that the approximate linearity of the dose-response together with lung burden measurements in youger people will provide reasonably reliable predictions of future mesothelioma rates in those norn since 1965.

Critical reappraisal of Balangero chrysotile and mesothelioma risk
Edward B. Ilgren, Frederick D. Pooley, Yumi M Kumiya and John A. Hoskins

Epidemiology Biostatistics and Public Health - 2015, Volume 12, Number 1

Balangero, located some 40 km northwest of Torino in Italy, was home to the largest and most active chrysotile mine in Europe operating from 1916 – 1990. and employed over 300 men at any one time. The chrysotile was thought to be pure. However, claims were made that it had been responsible for causing numerous mesotheliomas. The authors of this report refute this claim on the grounds that it is not pure but potentially contaminated by tremolite asbestos. In addition they found numerous alternate sources of naturally occurring and commercially available amphibole asbestos in the region. The authors mention geological studies that illustrate the presence of naturally occurring tremolite and various analyses showing naturally occurring and commercially used amphibole by its presence in animal and human tissue.

Several authors have searched available registries for post-mortem information and listed possible mesothelioma cases. Cross-matching these searches has been attempted and the strength of their diagnoses examined. Their conclusions: There is good evidence that crocidolite, amosite and tremolite are responsible for the alleged mesothelioma cases at Balangero. The authors found several sources of naturally occurring and commercial amphibole asbestos in the region to account for the alleged cases.

In an accompanying paper (same reference, entitled « Supplemantal Data », the authors indicate that vast amounts of amphibole asbestos were imported from South Africa used in the manufacture of several products around Torino where cases of mesothelioma were recorded. Clusters of the desease extended to the Balangero area. The authors mention that crocidolite asbestos cement from Casale was also said to be used in the town of Balangero.

Airborne asbestos take-home exposures during handling of chrysotile-contaminated clothing following simulated full shift workplace exposures.

Journal of Exposure Science and Environmemental Epidemiology (April 29, 2015 Jenifer Shmel et al.)

This article, authored by Jennifer Sahmel and several colleagues, is an extension of their previously published research on airborne asbestos exposure potential associated with the handling of chrysotile-contaminated work clothes. The present study extends that work by assessing several different exposure conditions, including sustained exposures representing a full work shift.

In the current study, the authors evaluated take home exposures associated with clothes handling following full shift exposures to airborne chrysotile at 9 f/cc as an 8-hr time-weighted average (TWA). The resulting airborne TWA concentrations for simulated weekly clothes handling activity were approximately 0.2–1% of the simulated workplace TWAs, consistent with previously published research.

South African experience with asbestos related environmental mesothelioma: Is asbestos fiber type important?

Regulatory Toxicology and Pharmacology (2008) Volume 52, Issue 1, Supplement, pp. S92–S96

Neil Whitea^{a, †}, Gill Nelsonb^b, Jill

Abstract

It well known that South Africa (SA),has mined and milled all three commercially important asbestos minerals. Proven cases of mesothelioma have been linked with environmental exposure to asbestos. In this study, the authors illustrate the importance of fiber type in the occurrence of environmental mesothelioma. Studies have reviewed the source of occupational or environmental asbestos exposure in 504 histologically proven cases of mesothelioma in. 23% of cases were thought to be related to environmental exposure to asbestos. The vast majority of these cases were related to exposure to crocidolite mining activities in the Northern Cape Province. No cases were reported with exposure to South African chrysotile.

In the vast majority of cases of mesothelioma, environmental exposure to asbestos occurred in the Northern Cape Province, in proximity to mines, mills and dumps where crocidolite was processed. Crocidolite appears to be far more mesotheliomagenic than amosite, and chrysotile has not been implicated in the disease. This is true for both occupationally and environmentally exposed individuals.

A presentation in Malaysia (February25, 2015) by Dr. Robert Nolan of the International Environmental Foundation (New York), entitled "Scientific Update on Safe Use of Asbestos"

Click here to download the PowerPoint presentation. (9.6 mb)

Evaluation of the scientific basis for the WHO’s statement on asbestos

The World Health Organization (WHO) has issued a document entitled “Elimination of asbestos related diseases” which provides the scientific basis for the WHO statement that there are about 107,000 deaths related to asbestos. The WHO web site states that “According to WHO estimates, more than 107,000 people die each year from asbestos-related lung cancer, mesothelioma and asbestosis resulting from occupational exposures.”

The implication in this document as well as in the WHO document “Model National Programme for Elimination of Asbestos-Related Diseases” , is that chrysotile as used today is largely responsible for these deaths.

The document states that the WHO estimated the number of deaths related to asbestos in their document by Ezzati et al. (2004) entitled “Comparative Quantification of Health Risks: Global and Regional Burden of Disease Attribution to Selected Major Risk Factors”. They cite the chapter by Concha-Barrientos, et al. in Volume 2, Chapter 21: “Selected occupational risk factors” of this document in support of their statement:

“Asbestos is one of the most important occupational carcinogens causing about half of the deaths from occupational cancer”

However, in the entire document by Ezzati et al. (2004), the word chrysotile appears one time on page 1687 in the following statement:

“In 20 studies of over 100,000 asbestos workers, the standardized mortality rate ranged from 1.04 for chrysotile workers to 4.97 for amosite workers, with a combined relative risk of 2.00. It is difficult to determine the exposures involved because few of the studies reported measurements, and because it is a problem to convert historical asbestos measurements in millions of dust particles per cubic foot to gravimetric units. Nevertheless, little excess lung cancer is expected from low exposure levels.”

The WHO Ezzati et al. (2004) document cites a review by Steenland et al. (1996) entitled “Review of Occupational Lung Carcinogens”. The Steenland et al. paper summarized 20 studies of asbestos workers exposed 20 to 50 years earlier with no assessment or differentiation of whether there was exposure to amphibole asbestos in those studies listed as chrysotile. The Ezzati et al. (2004) document, however, further states that little excess lung cancer is expected from low exposure levels, without mentioning asbestos fiber type.

Steenland et al. (1996) summarized the relative risk for a number of lung carcinogens as follows:

The relative risk for asbestos is listed as 2 based on how it was used 20 to 50 years ago (without differentiating whether it was chrysotile or amphibole asbestos). It is also interesting to note that arsenic and chromium have higher relative risks and that none of the other agents listed are banned.

The WHO also cites the more recent publication by Driscoll et al. (2005) in support of the statements entitled:

Driscoll T, Nelson Dl, Steenland K, Leigh J, Concha·Barrientos M, Fingerhut M, Prüss-Ustiln A: The global burden of non-malignant respiratory disease due to occupational airborne exposures. Am J Ind Med. 2005, 48;432-45,

In the paper by Driscoll et al. the authors cite the more recent and considerably more complete publication by Hodgson and Darnton (2000) on asbestos risk which differentiates chrysotile from amphibole asbestos and not the older paper by Steenland et al. (1996).

Driscoll et al. states that:

“This combined estimate is based on best estimates of risk of 400 per 100 000/fibre.year per ml for crocidolite, 65 per 100 000/fibre.year per ml for amosite and 2 per 100 000/fibre.year per ml for chrysotile, and the changing mixture of amphiboles and chrysotile that has characterised exposure 20 and 50 years ago [Hodgson and Darnton, 2000].”

In another publication from the WHO entitled:

Prüss-Ustiln A, Vickers C, Haefliger P, Bertollini B. Knowns and unknowns on burden of disease due to chemicals; a systematic review. Environmental Health. 2011, 10:9.

The authors state:

“The global burden of disease attributable to asbestos has been estimated to amount to 107,000 deaths and 1,523,000 DALYs for the three mentioned diseases in 2004.”

Prüss-Ustiln et al. (2011) cite three references in support of this statement. These include the Concha-Barrientos, et al. (2004) publication discussed above which clearly does not attribute the effect to chrysotile; the publication by Driscoll et al. (2005) which also clearly differentiates chrysotile effects from those from amphibole asbestos; and the WHO 2009 report entitled “Global health risks: mortality and burden of disease attributable to selected major risks⁴” which does not ever mention the word chrysotile.

In the paper by Prüss-Ustiln et al. (2011), chrysotile is also not ever mentioned in the text. Any possible relationship of the “107,000 deaths” to chrysotile is certainly not supported by this paper. The references cited by Prüss-Ustiln et al. (2011) for the 107,000 deaths per year are the same as mentioned above and are based upon the exposure to all types of asbestos (amosite, crocidolite and chrysotile asbestos) at the exposure concentrations that occurred 20 to 50 years ago.

From the publication by Hodgson and Darnton, 2000, based upon exposure levels 20-50 years ago and the analysis of studies as “chrysotile” which actually had exposures to amphibole asbestos (Bernstein et al., 2013), the calculated mesothelioma risk for chrysotile is 2 per 100 000/fibre.year per ml. As explained by Bernstein et al. (2013), with the elimination of amphibole use today and under the controlled use employed which greatly reduces potential exposure, the risk for mesothelioma today would be very low. Similarly, Ezzati et al. (2004) stated that: “little excess lung cancer is expected from low exposure levels”.

In addition the most recent evaluation of scientific evidence performed by the International Agency for Research on Cancer (IARC Monograph 100c) which stated that all forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite and anthophyllite) are carcinogenic to humans (Group 1) was also based upon exposure concentrations that occurred 20 to 50 years ago using studies as chrysotile only in which there was amphibole asbestos exposure. The IARC classification is a hazard classification based upon whether any study has reported an effect at any time and at any exposure concentration. It does not provide an assessment of risk today from exposure to chrysotile alone (with no amphibole asbestos) at exposure concentration that occur with controlled use.

The documents put forward by the WHO clearly do not support the statement that the 107,000 deaths per year are occurring today and provide no basis for attributing these to chrysotile.

David Bernstein, Ph.D.
Jacques Dunnigan, Ph.D
John Hoskins, Ph.D
20 August 2014

References

Bernstein D, Dunnigan J, Hesterberg T, Brown R, Velasco JA, Barrera R, Hoskins J, Gibbs A. 2013 Health risk of chrysotile revisited. Crit Rev Toxicol. 2013 Feb;43(2):154-83.

Broeck, J.; Brestoff, J. R.; Kaulfuss, C. (2013). "Statistical Estimation". Epidemiology: Principles and Practical Guidelines. p. 417.

Driscoll T, Nelson Dl, Steenland K, Leigh J, Concha·Barrientos M, Fingerhut M, Prüss-Ustiln A: The global burden of non-malignant respiratory disease due to occupational airborne exposures. Am J Ind Med. 2005, 48;432-45.

Ezzati, M, Lopez, AD, Rodgers, A and Murray, CJL. Editors. 2004. Comparative Quantification of Health Risks Global and Regional Burden of Disease Attributable to Selected Major Risk Factors Volume 2, World Health Organization.

Hodgson J, Darnton A (2000). The quantitative risks of mesothelioma and lung cancer in relation to asbestos exposure. Annals of Occupational Hygiene, 44:565-601.

Prüss-Ustiln A, Vickers C, Haefliger P, Bertollini B, Knowns and unknowns on burden of disease due to chemicals; a systematic review. Environmental Health. 2011, 10:9.

Steenland K, Loomis D, Shy C, Simonsen N (1996) Review of occupational lung carcinogens. American Journal of Industrial Medicine, 29:474–490.

Regional variations in German mesothelioma mortality rates: 2000–2010

Cancer Causes & Control (2014) Volume 25, Issue 5, pp. 615-624

Sara J. Schonfeld, Valerie McCormack, Mark J. Rutherford, Joachim Schüz

This is a study on geografical differences in mesothelioma mortality rates in two parts of Germany with data coming from the former West Germany which had access to amphibole sources from South Africa, while East Germany relied almost exclusively on chrysotile from Canada, and possibly other chrysotile-only sources.

As mesothelioma occurs many (≥30) years after asbestos exposure, contemporary rates likely reflect exposures in the 1960–1970s. During this period, political division between West and East Germany led to differences regarding the import and consumption of asbestos of asbestos fiber types, West germany having access to large imports of amohiboles, while East germany The authors focused in particular on regional variations in mesothelioma mortality rates in in 2000–2010. They calculated truncated (≥40 years) age-standardized mesothelioma mortality rates (ASRs40+) per 100,000 person-years. There were 12,854 mesothelioma deaths at ages ≥ 40 years in Germany during 2000–2010. ASRs40+ were higher in West (males 4.4; females 0.8) than East (males 1.7; females 0.6) Germany.

The authors conclude that these geographical differences in mesothelioma mortality rates are consistent with heterogeneous historical asbestos exposures. They suggest that differences may also exist for other asbestos-related cancers and should be investigated. Incidentally, this study appears in line with many other studies confirming the vast difference with regard to the mesotheliomagenic potential between amphiboles and chrysotile. Among such studies are :
-Wagner, J.C., Newhouse, M.L., Corrin, B., Rossiter, C.E. and Griffiths, D.M. (1988). Correlation between fibre content of the lung and disease in East London asbestos factory workers. British Journal of Industrial Medicine 45(5):305-308 ; -Kleinerman, J. (1988). The pathology of asbestos related lung disease, Proceedings, The Fleischner Society, Eighteenth Annual Symposium on Chest Disease, Montréal, Canada, 16-18 May, pp. 33-46 ; -Gardner, M.J. and Powell, C.A. (1986). Mortality of asbestos cement workers using almost exclusively chrysotile fibre. Journal of the Society of Occupational Medicine 36(4):124-126 ; - ---Berry, G. and Newhouse, M.L. (1983). Mortality of workers manufacturing friction materials using asbestos. British Journal of Industrial Medicine 40(1):1-7. -Thomas, H.F., Benjamin, I.T., Elwood, P.C. and Sweetnam, P.M. (1982). Further follow-up study of workers from an asbestos cement factory. British Journal of Industrial Medicine 39(3):273-276.

South African experience with asbestos related environmental mesothelioma: Is asbestos fiber type important?

Regulatory Toxicology and Pharmacology (2008) Volume 52, Issue 1, Supplement, pp. S92–S96

Neil Whitea, †, Gill Nelsonb, Jill

It well known that South Africa (SA),has mined and milled all three commercially important asbestos minerals. Proven cases of mesothelioma have been linked with environmental exposure to asbestos. In this study, the authors illustrate the importance of fiber type in the occurrence of environmental mesothelioma. Studies have reviewed the source of occupational or environmental asbestos exposure in 504 histologically proven cases of mesothelioma in. 23% of cases were thought to be related to environmental exposure to asbestos. The vast majority of these cases were related to exposure to crocidolite mining activities in the Northern Cape Province. No cases were reported with exposure to South African chrysotile.

In the vast majority of cases of mesothelioma, environmental exposure to asbestos occurred in the Northern Cape Province, in proximity to mines, mills and dumps where crocidolite was processed. Crocidolite appears to be far more mesotheliomagenic than amosite, and chrysotile has not been implicated in the disease. This is true for both occupationally and environmentally exposed individuals.

The health risk of chrysotile asbestos

Current Opinion in Pulmonary Medicine (2014) Vol. 20, No. 4, 389-392

David Bernstein

Abstract

This review clarifies the differences between the two mineral families (chrysotile and amphiboles) referred to as « asbestos » The author summarizes the scientific basis for understanding the important differences in the toxicology and epidemiology of these two minerals. Biopersistence studies and sub-chronic inhalation toxicology studies have shown that exposure to chrysotile at up to 5,000 times the current threshold limit value (0.1 fibers/cm3) produces no pathological response. These studies demonstrate as well that following short-term exposure the longer chrysotile fibers rapidly clear from the lung and are not observed in the pleural cavity. In contrast, short-term exposure to amphibole asbestos results quickly in the initiation of a pathological response in the lung and the pleural cavity.

The author concludes that the valuation of the toxicology and epidemiology studies of chrysotile indicates that it can be used safely under controlled use. In contrast, even short-term exposure to amphibole asbestos can result in disease.

The review is available here.

Potential health hazards associated with exposures to asbestos-containing drywall accessory products: A state-of-the-science assessment

Critical Reviews in Toxicology (2012) Vol. 42, No. 1 , Pages 1-27

Amanda D. Phelka¹, Brent L. Finley²

In this review on the risk assocated with the presence of asbestos as an ingredient in most industrial and consumer drywall accessory products such as patching compounds. The authors mention that in 1977, the Consumer Product Safety Commission (CPSC) had issued a ban of consumer patching compounds containing “respirable, free-form asbestos” based on their prediction of exceptionally high rates of asbestos-related diseases among individuals using patching compounds for as little as a few days.

The authors provide a comprehensive review and analysis of the scientific studies assessing fiber type and dimension, toxicological and epidemiological endpoints, and airborne fiber concentrations associated with joint compound use. They conclude that:

1. asbestos in drywall accessory products was primarily short fiber (< 5 µm) chrysotile,

2. asbestos in inhaled joint compound particulate is probably not biopersistent in the lung,

3. estimated cumulative chrysotile exposures experienced by workers and homeowners are below levels known to be associated with respiratory disease, and

4. mortality studies of drywall installers have not demonstrated a significantly increased incidence of death attributable to any asbestos-related disease. Consequently, contrary to the predictions of the CPSC, the current weight of evidence does not indicate any clear health risks associated with the use of asbestos-containing drywall accessory products.

Asbestos Content of Heavy Equipment Brake-Wear Debris and Associated Airborne Exposure During Brake Work

Society of Toxicology 53rd Annual Meeting and ToxExpo Phoenix, AZ. March 23-27, 2014

Grespin, M.E., E.D. Donovan, R.J. Ward, A.K. Madl, and B.L. Finley

Abstract
This study was performed to determine whether individuals working with heavy equipment brake components, or bystanders to such work, were exposed to chrysotile asbestos above exposure limits dependent upon chrysotile content of equipment brake wear debris (BWD) and type of machinery. Publicly available published and unpublished studies examining BWD asbestos content in various heavy equipment were identified. Variables potentially contributing to BWD and airborne asbestos concentrations included common brake job practices, infrequent manipulative activities, cleaning methods, and brake component dimensionality. Tasks included combinations of changing brakes, inspection of brake pads, glazing breaks with sandpaper, and cleaning with solvent or compressed air. The degree to which airborne asbestos concentrations correlated to BWD composition and physical characteristics, the type of heavy machinery, and the brake work activities was determined. Most, but not all, BWD samples contained less than one percent chrysotile by weight. For air samples, phase contrast microscopy results for personal, bystander and area samples did not exceed 0.622 total f/cc based on short-term, task-based sampling. 8-hr time weighted average concentrations did not exceed 0.045 asbestos f/cc after adjusting for asbestos content using transmission electron microscopy. These results are consistent with those observed for smaller vehicles, including automobiles. This suggests that individuals working with these materials would not have been exposed to asbestos above contemporaneous or current exposure limits, regardless of BWD chrysotile content. It is unlikely that the dimension of brake components influences the degree to which mechanics working with such products were historically exposed to asbestos.

EVOLUTION OF WORLD PRODUCTION AND CONSUMPTION OF ASBESTOS
(Metric tons, all types)

(Source : US Department of Interior, US Geological Survey)

Evaluation of the deposition, translocation and pathological response of brake dust with and without added chrysotile in comparison to crocidolite asbestos following short-term inhalation: Interim results

Toxicology and Applied Pharmacology (2014) Vol 276, No. 1, pp. 28-46

David M. Bernstein, Rick Rogers, Rosalina Sepulveda, Peter Kunzendorf, Bernd Bellmann, Heinrich Ernst, James I. Phillips

This study was designed to provide an understanding of the biokinetics and potential toxicology following inhalation of brake dust following short term exposure in rats. The deposition, translocation and pathological response of brake dust derived from brake pads manufactured with chrysotile were evaluated in comparison to the amphibole, crocidolite asbestos. Rats were exposed by inhalation 6 h/day for 5 days to either brake dust obtained by sanding of brake-drums manufactured with chrysotile, a mixture of chrysotile and the brake dust or crocidolite asbestos. No significant pathological response was observed at any time point in either the brake dust or chrysotile/brake dust exposure groups. The long chrysotile fibers (> 20 µm) cleared quickly with T1/2 estimated as 30 and 33 days, respectively in the brake dust and the chrysotile/brake dust exposure groups. In contrast, the long crocidolite fibers had a T1/2 > 1000 days and initiated a rapid inflammatory response in the lung following exposure resulting in a 5-fold increase in fibrotic response within 91 days. These results provide support that brake dust derived from chrysotile containing brake drums would not initiate a pathological response in the lung following short term inhalation.

Cumulative Retrospective Exposure Assessment (REA) as a predictor of amphibole asbestos lung burden: validation procedures and results for industrial hygiene and pathology estimates

Posted online on January 9, 2014. (doi:10.3109/08958378.2013.845273)

James O. Rasmuson¹, Victor L. Roggli², Fred W. Boelter³, Eric J. Rasmuson¹, and Charles F. Redinger⁴

A study conducted to compare retrospective exposure assessment (REA) and asbestos lung burden assessment (LBA). Both REA and pathology assessment (LBA) are reliable and complementary predictive methods to characterize asbestos exposures. Correlation analysis between the two methods effectively validates both REA methodology and LBA procedures within the determined precision, particularly for cumulative amphibole asbestos exposures since chrysotile fibers, for the most part, are not retained in the lung for an extended period of time.

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Journal of Immunotoxicology
Posted online on October 28, 2013. (doi:10.3109/1547691X.2013.847510)

Aaron Ferro¹, Christian Nash Zebedeo², Chad Davis², Kok Whei Ng², and Jean C. Pfau²

This srudy aims to demonstrate that while exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, serum ANA/ENA (antinuclear antibodies/extractable nuclear antigens) were analysed following chalenges with both amphibole and chrysotile.
Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.

Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature

Critical reviews in Toxicology, October 2012, Vol. 42, No. 9 , Pages 703-731

Ellen P. Donovan¹, Brooke L. Donovan¹, Meg A. McKinley¹, Dallas M. Cowan², Dennis J. Paustenbach¹

In this review article, the authors have conducted a literature review in order to characterize reported cases of asbestos-related disease among household contacts of workers occupationally exposed to asbestos. In some 60 articles, cases of asbestos-related disease are described and thought to be caused by para-occupational exposure, over 65% of these cases were in persons who lived with workers classified as miners, shipyard workers, insulators, or others involved in the manufacturing of asbestos-containing products, with nearly all remaining workers identified as craftsmen. 98% of the available lung samples of the persons with diseases indicated the presence of amphibole asbestos. The authors indicate that the literature is dominated by case reports, the majority of which involved household contacts of workers in industries characterized, generally, by high exposures to amphiboles or mixed mineral types. The available data do not implicate chrysotile as a significant cause of disease for household contacts.

Biodurability/Retention of Libby Amphiboles in a Case of Mesothelioma

Posted online on October 17, 2013. (doi:10.3109/01913123.2013.821194)

Ronald F. Dodson, PhD¹, Eugene J. Mark, MD², and Lee W. Poye, BS^{3 1}Dodson Environmental Consulting, Inc. and ERI Environmental Consulting, Inc., Tyler, Texas USA

This present case study reports on tissue burden of fibrous dust in a person who used a vermiculite material (Zonolite) as an attic insulator some 50 years prior to her death. The exposure occurred in her private residencies. She potentially had exposures to wall board/joint compounds during renovations. She additionally was reported to occasionally be involved in occupational activity, including drilling holes in presumed asbestos-containing electrical boxes. Tissue burden analysis revealed the presence of noncommercial amphibole asbestos fibers and consistent presence in the lung and lymph samples of Libby amphibole fibers. The findings of Libby amphibole fibers in human tissue can be attributed to exposure to Libby vermiculite. This is an illustration that analytical transmission electron microscopy can distinguish these structures from “asbestos” fibers. The findings also indicate that a population of these structures is biodurable and retained in the tissue years after first/last exposure.

Domestic asbestos exposure: a review of epidemiologic and exposure data.

Emily Goswami; Valerie Craven; David L Dahlstrom; Dominik Alexander; Fionna Mowat
Int J Environ Res Public Health 10, 5629 (2013)

This review offers a meta-analysis that evaluates epidemiologic studies of asbestos-related disease or conditions (mesothelioma, lung cancer, and pleural and interstitial abnormalities) among domestically exposed individuals and exposure studies that provide either direct exposure measurements or surrogate measures of asbestos exposure.

The studies are limited with regard to lung cancer (n = 2). Several exposure-related studies describe results from airborne samples collected within the home (n = 3), during laundering of contaminated clothing (n = 1) or in controlled exposure simulations (n = 5) of domestic exposures, the latter of which were generally associated with low-level chrysotile-exposed workers. Lung burden studies (n = 6) were also evaluated as a surrogate of exposure. In general, available results for domestic exposures are lower than the workers' exposures. Recent simulations of low-level chrysotile-exposed workers indicate asbestos levels commensurate with background concentrations in those exposed domestically.

Identification of ferruginous bodies in the lungs of children and analyses of the elemental composition of fibers

Inhalation Toxicology, August 2013, Vol. 25, No. 9 , Pages 517-524

Pilar Eguía-Aguilar¹, Mario Pérezpeña-Díazconti¹, and Francisco Arenas-Huertero¹,²

Ferruginous bodies (FBs) are iron-coated entities that form in the body around inorganic fibers or other particulates. Studies of FB have been conducted consistently in the lungs of adults but have not been explored in children during the past 20 years. The objective of this study was to quantify the FBs, classify them as to morphological type and conduct a mineralogical analysis using the energy dispersive X-ray microanalysis (EDXA) with samples obtained from 72 autopsies performed on children.

Three grams of lung tissue were digested in commercial bleach, and all the FB found were quantified. The FB from the positive cases was analyzed by EDXA. Results show that 17% of cases presented FB with a median concentration of 5.7 ferruginous bodies per gram of dry weight (FB/g). Larger quantities of FB were recovered from the lungs of rural residents, at concentrations of 11.33 FB/g. Ten cases of children under 5 years of age also presented 5.7 FB/g, but none of these groups showed significant differences when compared to populations of children residing in Mexico City or to children over 5 years of age (p > 0.05). Type-1 FB was the predominant morphological form present. All FBs were aluminosilicates. It can be concluded that Mexican children retain FBs at low concentrations. All the cores of the FB analyzed in this study were aluminosilicates. Only one contained kaolinite, while the other 10 consisted of some kind of feldspar or clay-like mineral and may thus reflect intramural exposure in children.

Biodurability/Retention of Libby Amphiboles in a Case of Mesothelioma

Ultrastructural Pathology : Posted online on October 17, 2013.
(doi:10.3109/01913123.2013.821194)

Ronald F. Dodson, PhD1, Eugene J. Mark, MD2, and Lee W. Poye, BS3

This is a case study reporting on tissue burden of fibrous dust in a women who used a vermiculite material (Zonolite) as an attic insulator some 50 years prior to her death.

The exposure occurred in two construction/renovation projects in her private residencies. She potentially had exposures to wall board/joint compounds during renovations. The tissue burden analysis revealed the presence of noncommercial amphibole asbestos fibers and consistent with the presence in the lung and lymph samples of Libby amphibole fibers. The findings of Libby amphibole fibers in human tissue can be attributed to exposure to Libby vermiculite. There is no report of chrysotile fibers accumulation in her lung tissues. This study illustrates that analytical transmission electron microscopy can distinguish these structures from "asbestos" fibers, and indicates that a population of these structures is biodurable and retained in the tissue years after first/last exposure.

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Journal of Immuntoxicoloy
Posted online on October 28, 2013. (doi:10.3109/1547691X.2013.847510)

Aaron Ferro¹, Christian Nash Zebedeo², Chad Davis², Kok Whei Ng², and Jean C. Pfau<sup>2

1</sup>Pacific Northwest University of Health Sciences, College of Osteopathic Medicine, Yakima, WA, USA and ²Idaho State University, Department of Biological Sciences, Pocatello, ID, USA

It is known that exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and also increases the risk of systemic autoimmune disease.

Eight months after the final treatments with amphiboles and chrysotile, the authors exanined the changes in serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes. The results show that amphiboles, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17, an interleukin which induces the production of pro-inflammatory cytokines. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice.

Evaluation of take home (para-occupational) exposure to asbestos and disease: a review of the literature.

Crit Rev Toxicol. 2012; 42(9):703-31 (ISSN: 1547-6898)

Donovan EP; Donovan BL; McKinley MA; Cowan DM; Paustenbach DJ, ChemRisk LLC, San Francisco, CA 94105, USA. edonovan@chemrisk.com

In this review article, the authors have covered over 200 published articles where some Nearly 60 articles described cases of asbestos-related disease thought to be caused by para-occupational exposure. Over 65% of these cases were in persons who lived with workers classified as miners, shipyard workers, insulators, or others involved in the manufacturing of asbestos-containing products, with nearly all remaining workers identified as craftsmen. 98% of the available lung samples of the persons with diseases indicated the presence of amphibole asbestos. Eight studies provided airborne asbestos concentrations during (i) handling of clothing contaminated with asbestos during insulation work or simulated use of friction products; (ii) ambient conditions in the homes of asbestos miners; and (iii) wearing previously contaminated clothing. This review indicates that the literature is dominated by case reports, the majority of which involved household contacts of workers in industries characterized, generally, by high exposures to amphiboles or mixed mineral types. The available data do not implicate chrysotile as a significant cause of disease for household contacts.

Asbestos Fibre Burden in the Lungs of Patients with Mesothelioma Who Lived Near Asbestos-Cement Factories

Ann Occcup Hyg (2012) Vol 56, 660-670,

Barbieri GP, Mirabelli D, Somigliana A, Cavone C, Merler E

Epidemics of malignant mesothelioma are occurring among inhabitants of Casale Monferrato and Bari never employed in the local asbestos-cement (AC) factories. Analysis was performed by a scanning electron microscope equipped with X-ray microanalysis wet (formalin-fixed) lung tissue samples from eight mesothelioma patients who lived in Casale Monferrato or Bari and underwent surgery.

The lung fibre burden ranged from 110 000 to 4 300 000 fibres per gram of dry lung (f/g) and was >1 000 000 f/g in three subjects. Of the eight mesothelioma cases, only amphibole fibres were detected in four cases, and mixed fiber types were detected in the other four cases. Environmental exposures had ceased at least 10 years before samples were taken.

The authors conclude that environmental exposure to a mixture of asbestos fibres may lead to a high lung fibre burden of amphiboles years after exposure cessation.

Potential health hazards associated with exposures to asbestos-containing drywall accessory products: A state-of-the-science assessment

Critical Review in Toxicology. January 2012, Vol. 42, No. 1 , Pages 1-27

Amanda D. Phelka¹, Brent L. Finley^2
1ChemRisk LLC, Chicago, IL, USA²
ChemRisk LLC, San Francisco, CA, USA

Until the late 1970s, chrysotile asbestos was an ingredient incorporated in most industrial and consumer drywall accessory products manufactured in the US. In 197. Prediction of exceptionally high rates of asbestos-related diseases among individuals using patching compounds for as little as a few days had led the Consumer Product Safety Commission (CPSC) to issue a ban of consumer patching compounds containing "respirable, free-form asbestos" Although hundreds of thousands of workers and homeowners handling these products may have experienced exposure to asbestos prior to the ban, there has been no systematic effort to summarize and interpret the information relevant to the potential health effects of such exposures. The review is meant to provide a comprehensive review and analysis of the scientific studies assessing fiber type and dimension, toxicological and epidemiological endpoints, and airborne fiber concentrations associated with joint compound use. The authors find that asbestos in drywall accessory products is primarily short fiber (< 5 µm) chrysotile, that estimated cumulative chrysotile exposures experienced by workers and homeowners are below levels known to be associated with respiratory disease, and mortality studies of drywall installers have not demonstrated a significantly increased incidence of death attributable to any asbestos-related disease.

The authors state that contrary to the alarmist predictions of the CPSC, the current weight of evidence does not indicate any clear health risks associated with the use of asbestos-containing drywall accessory products.

Asbestos fiber concentrations in the lungs of brake repair workers: commercial amphiboles levels are predictive of chrysotile levels

Inhalation Toxicology. October 2011, Vol. 23, No. 12 , Pages 681-688

Gary M. Marsh1, Ada O. Youk¹, Victor L. Roggli^2
1Department of Biostatistics, Graduate School of Public Health, Center for Occupational Biostatistics and Epidemiology,
University of Pittsburgh, Pittsburgh, PA, USA
²Department of Pathology, Duke University Medical Center, Durham, NC, USA

The authors investigated the lung levels of commercial and non-commercial amphiboles (principally tremolite as a marker for chrysotile asbestos) in brake repair workers with mesothelioma. 15 persons whose only known exposure to asbestos was through brake repair work were investigated to evaluate whether case-reported duration of employment as a brake repair worker predicted lung levels of commercial amphiboles or tremolite. The authors found that their data provided no evidence that duration of employment as a brake repair worker was a predictor of lung levels of tremolite or commercial amphiboles. Their findings also suggest that elevated lung levels of tremolite in the lungs of brake repair workers with elevated levels of amphiboles arose from concurrent exposures to commercial amphibole and chrysotile asbestos in occupational settings other than brake repair work. The weight of the scientific evidence does not support a role for occupational exposure to brake dust and other friction products in the development of mesothelioma.

Lung cancer and mesothelioma risk assessment for a population environmentally exposed to asbestos.

Int J Hyg Environ Health. 2013 Jul 20. pii: S1438-4639

Bourgault MH, Gagné M, Valcke M.
Institut national de santé publique du Québec (INSPQ), Montréal, Québec, Canada.
Electronic address: marie-helene.bourgault@inspq.qc.ca.

Recent published data on asbestos environmental concentrations in Thetford Mines, a mining city in Quebec, Canada, provided an opportunity to undertake a prospective cancer risk assessment in the 'general population' exposed to these concentrations. This 'general population' includes smokers and non-smokers, mining as well as non-occupationaly exposed population. Using an updated Berman and Crump dose-response model for asbestos exposure, the authors selected population-specific potency factors for lung cancer and mesothelioma. These factors were evaluated on the basis of population-specific cancer data attributed to the studied area's past environmental levels of asbestos. they also used more recent population-specific mortality data along with the validated potency factors to generate corresponding inhalation unit risks. These unit risks were then combined with recent environmental measurements made in the mining town to calculate estimated lifetime risk of asbestos-induced lung cancer and mesothelioma. Depending on the chosen potency factors, the lifetime mortality risks varied between 0.7(best estimate) and 2.6(upper bound) per 100,000 for lung cancer, and between 0.7 and 2.3 per 100,000 for mesothelioma.

The authors concluded that the estimated lifetime cancer risk for both cancers combined is close to Health Canada's threshold for "negligible" lifetime cancer risks.

Health risk of chrysotile revisited

Crit Rev Toxicol, 2013; 43(2): 154-183 (Open Access)

David Bernstein, Jacques Dunnigan, Thomas Hesterberg, Robert Brown, Juan Antonio Legaspi Velasco, Raul Barrera, John Hoskins, and Allen Gibbs (OPEN ACCESS)

Abstract : This review provides a basis for substantiating both kinetically and pathologically the differences between chrysotile and amphibole asbestos. Chrysotile, which is rapidly attacked by the acid environment of the macrophage, falls apart in the lung into short fibers and particles, while the amphibole asbestos persist creating a response to the fibrous structure of this mineral. Inhalation toxicity studies of chrysotile at non-lung overload conditions demonstrate that the long (>20µm} fibers are rapidly cleared from the lung, are not translocated to the pleural cavity and do not initiate fibrogenic response. In contrast, long amphibole asbestos fibers persist, are quickly (within 7d} translocated to the pleural cavity and result in interstitial fibrosis and pleural inflammation. Quantitative reviews of epidemiological studies of mineral fibers have determined the potency of chrysotile and amphibole asbestos for causing lung cancer and mesothelioma in relation to fiber type and have also differentiated between these two minerals. These studies have been reviewed in light of the frequent use of amphibole asbestos. As with other respirable particulates, there is evidence that heavy and prolonged exposure to chrysotile can produce lung cancer. The importance of the present and other similar reviews is that the studies they report show that low exposures to chrysotile do not present a detectable risk to health. Since total dose over time decides the likelihood of disease occurrence and progression, they also suggest that the risk of an adverse outcome may be low with even high exposures experienced over a short duration.

A retrospective cohort study of cancer mortality in employees of a Russian chrysotile asbestos mine and mills: Study rationale and key features Cancer Epidemiology

(Accepted 2 March 2013)
Available online : www.cancerepidemiology.net

J. Schüz ^a,*, S.J. Schonfeld ^a, H. Kromhout ^b, K. Straif ^c, S.V. Kashanskiy ^d, E.V. Kovalevskiy ^e, I.V. Bukhtiyarov ^e, V. McCormack ^a

^a Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France
^b Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands
^c Section of IARC Monographs, International Agency for Research on Cancer, Lyon, France
^d Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Yekaterinburg, Russian Federation
^e Scientific Research Institute of Occupational Health of the Russian Academy of Medical Sciences, Moscow, Russian Federation

The authors from France, the Netherlands and Russia have begun fieldwork on a retrospective cohort study of employees of one of the world’s largest chrysotile mine and mills, situated in Asbest, Russia. The primary aim of the study is to better characterize and quantify the risk of cancer mortality in terms of (i) the dose - response relationship of exposure with risk; (ii) the range of cancer sites affected, including female - specific cancers; and (iii) effects of duration of exposure and latency periods. This information will should help in understanding of the scale of the impending cancer burden due to chrysotile, including if chrysotile use ceased worldwide forthwith. In this publication, the authors describe the scientific rationale for conducting this study and the main features of its study design.

Change of carcinogenic chrysotile fibers in the asbestos cement (eternit) to harmless waste by artificial carbonatization: Petrological and technological results.

Source

J. Hazard. Mater. 252-253, 390-400 (2013)

Martin Radvanec; Lubomír Tuček; Ján Derco; Katarína Cechovská; Zoltán Németh

This article presents a procedure and experimental results of artificial carbonatization, applied in to asbestos cement (eternit). The wet crushed and pulverized asbestos cement is first thermally modified at 650°C. Then the chrysotile fibers are easily and completely reacted with a mixture of CO2 and water, producing new Mg-rich carbonates - hydromagnesite and magnesite: Applying this methodology, the asbestos-bearing waste can be stabilized and environmentally friendly permanently deposited. This procedure may be a way of neutralizing of extreme pH values (around 12) at large eternit dumps. Simultaneously, the artificial carbonatization of chrysotile asbestos by applying CO2 offers an alternative way for permanent elimination of a part of industrial CO2 emissions, thus contributing to multiple benefits of this methodology.

Mesothelioma and Analysis of Tissue Fiber Content.

Recent Results Cancer Res. 189, 79 (2011)

Source

Volker Neumann; Stefan Löseke; Andrea Tannapfel. German Mesothelioma Register, University Hospital Bergmannsheil, Bochum, Germany. volker.neumann@ruhr-uni-bochum.de

A study was conducted at the German Mesothelioma Registry in Bochum, Germany on the relationship between mesothelioma and asbestos exposure. The study was based on the fact that mineral analysis of lung tissue can provide valuable information for the research of asbestos-related diseases and for assessment of exposure.

Their analysis of lung tissue for asbestos burden led the authors to state that « The predominant fiber-type identified by electron microscopy in patients with mesothelioma is amphibole asbestos (crocidolite or amosite). »

Critical Reviews in Toxicology

This review provides a basis for substantiating both kinetically and pathologically the differences between chrysotile and amphibole asbestos. Chrysotile, which is rapidly attacked by the acid environment of the macrophage, falls apart in the lung into short fibers and particles, while the amphibole asbestos persist creating a response to the fibrous structure of this mineral. Inhalation toxicity studies of chrysotile at non-lung overload conditions demonstrate that the long (420 mm) fibers are rapidly cleared from the lung, are not translocated to the pleural cavity and do not initiate fibrogenic response. In contrast, long amphibole asbestos fibers persist, are quickly (within 7 d) translocated to the pleural cavity and result in interstitial fibrosis and pleural inflammation. Quantitative reviews of epidemiological studies of mineral fibers have determined the potency of chrysotile and amphibole asbestos for causing lung cancer and mesothelioma in relation to fiber type and have also differentiated between these two minerals. These studies have been reviewed in light of the frequent use of amphibole asbestos. As with other respirable particulates, there is evidence that heavy and prolonged exposure to chrysotile can produce lung cancer. The importance of the present and other similar reviews is that the studies they report show that low exposures to chrysotile do not present a detectable risk to health. Since total dose over time decides the likelihood of disease occurrence and progression, they also suggest that the risk of an adverse outcome may be low with even high exposures experienced over a short duration.

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Review of the differences between chrysotile and amphibole asbestos

David M. Bernstein, Ph.D

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Safety in the Use of Chrysotile - Requirements and Achievements

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Safety in the Use of Chrysotile - A manual on preventive and control measures

Download document [.PDF, 5.3 Mo, 180p.]

Asbestos: The cause of 100,000 Deaths...yearly? MYTH OR REALITY?

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The Basics of Chrysotile Asbestos Dust Control

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Undeniable facts about chrysotile

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MORTALITY FROM OCCUPATIONAL EXPOSURE TO RELATIVELY PURE CHRYSOTILE: A 39-YEAR STUDY

Occupational exposure to relatively pure chrysotile within permissible levels was not associated with a significant increase in lung cancer or with mesothelioma. Decreased overall mortality of workers indicates a healthy worker effect, which – together with the relatively small cohort size – could have prevented small risks to e detected.
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Le monde du chrysotile en 2008

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Is Abestos Killing 100,000 People Each Year?

A careful examination of studies shows that this statement is grossly misleading and represents only selective parts of the scientific info.
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Asbestos Fibre Types and Health Risks

Are Perceptions Related to FACTS?
This document is a rapid overview of the recent scientific studies that support a controlled approach for the use of chrysotile and puts in perspective the pitfalls of over regulation.
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The Asbestos saga

Why so much emotion?
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IBE - Opinion Paper
Asbestos on the carcinogenic substances list
Scientists re-establish facts 

The health effects of chrysotile: Current perspective based upon recent data
David M. Bernstein, John A. Hoskins

Chrysotile as a Cause of Mesothelioma: An Assessment Based on Epidemiology
Charles M. Yarborough, Exponent, Inc., New York, New York, USA

The Toxicological Response of Brazilian Chrysotile Asbestos: A Multidose Subchronic 90-Day Inhalation Toxicology Study with 92-Day Recovery to Assess Cellular and Pathological Response
By: David M. Bernstein, Rick Rogers, Paul Smith, Jörg Chevalier

Inhalation Toxicology, Second Edition
By: David M. Bernstein

An Exposure Study of Bystanders and Workers During the Installation and Removal of Asbestos Gaskets and Packing
by: Carl Mangold, Katherine Clark, Amy Madl and Dennis Paustenbach

CASITILE, THE NEW ASBESTOS: Time to clear the air and save £20 billion
By: Professor John Bridle and Sophie Stone MSc BSc (Hons)

Understanding Chrysotile Asbestos: A New perspective Based upon Current Data
By: David M. Bernstein

The toxicological response of Brazilian chrysotile asbestos : A multi-dose sub-chronic 90-day inhalation toxicology study with 92 day recovery to assess cellular and pathological response.
By: David M. Bernstein

Occupational Environmental Medicine

The Asbestos Dilemma: I. Assessment of risk

The Asbestos Dilemma: II. The ban

Alarm rising in Denmark over plastic piping
Environment Daily 1395, 28/02/03

Special Report: Asbestos-Cement Pipe 
Chrysotile Asbestos-Cement (a/c) pipe has been used in water distribution systems around the world for more than 70 years. More than 2.5 million kilometres of a/c pipe are in use world wide. As this Special Report demonstrates, a/c pipe is cost effective, energy efficient, durable and safe. 

Understanding Mesothelioma 
This Special Report takes a look at some of the key studies conducted over the last 30 years and reviews the evidence relating to the nature of mesothelioma risks, their association with exposure to the different asbestos fibres, as well as findings that a significant percentage of cases appear to be unrelated to asbestos exposure. 

Special Report : Among The Least Hazardous Industrial Fibres