Chrysotile
Chrysotile | |
---|---|
dehydrates at 550–750 °C (1,022–1,382 °F) | |
Diagnostic features | White to grayish green thin, flexible curved fiber |
Solubility | Insoluble in water Fibres degrade in dilute acid |
References | [2][3][4] |
Chrysotile or white asbestos is the most commonly encountered form of
The material has physical properties which make it desirable for inclusion in building materials, but poses serious health risks when dispersed into air and inhaled.Polytypes
Three
Name | Crystal system | Type locality | mindat.org reference | Unit cell parameters | Crystal structure reference |
---|---|---|---|---|---|
Clinochrysotile | monoclinic
|
Złoty Stok*, Lower Silesia, Poland | a = 5.3 Å; b = 9.19 Å; c = 14.63 Å; β = 93° | [10] | |
Orthochrysotile | orthorhombic
|
Kadapa* district, Andhra Pradesh, India | a = 5.34 Å; b = 9.24 Å; c = 14.2 Å | [11] | |
Parachrysotile | orthorhombic
|
uncertain | a = 5.3 Å; b = 9.24 Å; c = 14.71 Å | [12] | |
Source: mindat.org. *Złoty Stok and Kadapa have formerly been known as Reichenstein and Cuddapah respectively, and these names may appear in some publications. |
Clinochrysotile is the most common of the three forms, found notably at
Physical properties
Bulk chrysotile has a hardness similar to a human
Chrysotile fibres have considerable
Chemical properties
The idealized
Chrysotile is resistant to even strong bases (asbestos is thus stable in high pH pore water of Portland
The global mass balance reaction of the chrysotile dehydration can be written as follows:
The chrysotile (serpentine) dehydration reaction corresponds to the reverse of the forsterite (Mg-
Applications
Previously, in the 1990s it was used in asbestos-cement products (like pipes and sheets).[14]
Magnesium sulfate (MgSO4) may be produced by treating chrysotile with sulfuric acid (H2SO4).[15]
Safety concerns
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/White_asbestos_%28Chrysotile%29.jpg/220px-White_asbestos_%28Chrysotile%29.jpg)
Chrysotile has been included with other forms of
Chrysotile has been recommended for inclusion in the Rotterdam Convention on Prior Informed Consent,[21] an international treaty that restricts the global trade in hazardous materials. If listed, exports of chrysotile would only be permitted to countries that explicitly consent to imports. Canada, a major producer of the mineral, has been harshly criticized by the Canadian Medical Association[22][23] for its opposition to including chrysotile in the convention.[24]
According to EU Regulation 1907/2006 (REACH) the marketing and use of chrysotile, and of products containing chrysotile, are prohibited.[25]
As of March 2024, the
Critics of safety regulations
1990s: Canada-European dispute GATT dispute
In May 1998, Canada requested consultations before the
2000s: Canadian exports face mounting global criticism
In the late 1990s and early 2000s, the Government of Canada continued to claim that chrysotile was much less dangerous than other types of asbestos.[28] Chrysotile continued to be used in new construction across Canada, in ways that are very similar to those for which chrysotile was exported.[29] Similarly, Natural Resources Canada once stated that chrysotile, one of the fibres that make up asbestos, was not as dangerous as once thought. According to a fact sheet from 2003, "current knowledge and modern technology can successfully control the potential for health and environmental harm posed by chrysotile".[30] The Chrysotile Institute, an association partially funded by the Canadian government, also prominently asserted that the use of chrysotile did not pose an environmental problem and the inherent risks in its use were limited to the workplace.[31]
However, under increasing criticism by environmental groups, in May, 2012, the Canadian government stopped funding the Chrysotile Institute.[32][33] As a result, the Chrysotile Institute has now closed.[34][35][36]
The Canadian government continues to draw both domestic and international criticism for its stance on chrysotile, most recently in international meetings about the
In September 2012, governments in Quebec and Canada ended official support for Canada's last asbestos mine in
See also
- Erionite
- Serpentinite reactions – Rock formed by hydration and metamorphic transformation of olivine
- Antigorite
References
- S2CID 235729616.
- ^ Mineralienatlas
- ^ Chrysotile on Mindat.org
- ^ Chrysotile data on Webmineral
- ^ a b c d e f "Asbestos" (PDF). Report on Carcinogens, Eleventh Edition. U.S. Department of Health and Human Services. 2005.
- ^ a b Occupational Safety and Health Administration, U.S. Department of Labor (2007). 29 C.F.R. 1910.1001. Appendix J.
- ^ a b c d Institut national de recherche sur la sécurité (1997). "Amiante Archived 2008-06-25 at the Wayback Machine." Fiches toxicologiques. n° 167. (in French)
- ^ Wicks, F. J.; Whittaker, E. J. W. (1975). "A reappraisal of the structures of the serpentine minerals". The Canadian Mineralogist. 13 (3): 227–243.
- doi:10.2113/gscanmin.44.6.1557. Archived from the original(PDF) on 2012-03-26. Retrieved 2010-11-30.
- .
- .
- .
- ^ In principle, all polytypes of chrysotile should have three independent refractive indices: in practice, two of the three are so close as to be indistinguishable by experimental measurement.
- PMID 7978966.
- ISSN 1313-0226.
- ^ International Agency for Research on Cancer (1998). "Asbestos." However, the study states " In some of these case reports and in other studies, asbestos fibres have been identified in the lung. Amphibole fibres have usually predominated, but in a few cases mainly or only chrysotile fibres were found." IARC Monographs on Evaluating the Carcinogenic Risks to Humans. Supplement 7 Archived 2008-03-06 at the Wayback Machine.
- ^ Agency for Toxic Substances and Disease Registry (ATDSR), U.S. Department of Health and Human Services (2007). "Asbestos Toxicity Archived June 6, 2011, at the Wayback Machine." Case Studies in Environmental Medicine.
- ^ "Archived copy" (PDF). Archived from the original (PDF) on 2010-06-09. Retrieved 2011-10-03.
{{cite web}}
: CS1 maint: archived copy as title (link) See e.g., Smith, Allen "Chrysotile is the main cause of pleural mesothelioma", Amer.J.Indus.Med., Vol. 32, pp. 252 to 266 (1996) - ^ [1] Tossavainen A, "Asbestos, asbestosis, and cancer: the Helsinki criteria for diagnosis and attribution" Scand J Work Environ Health 1997;23(4):311–316 (stating that all types of malignant mesothelioma can be induced by asbestos, with the amphiboles showing greater carcinogenic potency than chrysotile)
- PMID 20601327.
- ^ Rotterdam Convention: Chrysotile
- PMID 18936444.
- PMID 19047602.
- ^ MITTELSTAEDT, MARTIN (September 10, 2008). "Canada still blocking action on asbestos". The Globe and Mail. Toronto. Retrieved 2008-10-01.
- ^ Amtsblatt der Europäischen Union, L 396 from 30-12-2006 (PDF 1,8 MB; S. 129)
- ^ U.S. Bans the Last Type of Asbestos Still in Use by Coral Davenport in the New York Times, Mar. 18, 2024.
- ^ EC measures affecting asbestos products. World Trade Organization News. 29 October 1998
- ^ Harper, Tim (3 July 2011). "Canada diminished by asbestos hypocrisy". The Chronicle Herald. Archived from the original on 20 November 2012. Retrieved 28 September 2012.
- ^ Versailles, Guy (8 July 2015). "What Exactly Is Asbestos?". South Bay Mitigation.
- ^ "Chrysolite Asbestos Fact Sheet" (PDF). Natural Resources Canada. 3 February 2009. Archived from the original (PDF) on 27 September 2007. Retrieved 2010-01-12.
- ^ Vongdouangchanh, Bea (5 July 2011). "NDP MP Martin's one-man battle to ban asbestos mining in Canada gains traction". The Hill Times.
- ^ "Asbestos Advocacy Group Shuts Its Doors, Montreal Gazette". Archived from the original on 2012-07-10. Retrieved 2018-10-04.
- ^ "Canadian Cancer Society Disappointed with Proposed Federal Government Funding for Chrysotile Institute, 3 March 2012". Archived from the original on 28 June 2011. Retrieved 28 September 2012.
- ^ R.I.P. Chrysotile Institute, The Mad Scientist Blog>
- ^ Asbestos Advocacy Group Shuts Its Doors, Vancouver Sun, 29 April 2012[permanent dead link]
- ^ ""Minister Flaherty: Stop Funding The Chrysotile Institute", 2 Feb. 2011". Archived from the original on 2019-04-04. Retrieved 2012-09-28.
- ^ Stop Canada's Export Of Asbestos CFMEU Archived July 10, 2010, at the Wayback Machine
- ^ Daniel Lak (17 Oct 2012). "Canada axes support for asbestos mining". Al Jazeera.
External links
- The Chrysotile Institute
- International Chemical Safety Card 0014
- "Asbestos-containing Floor Tile and Mastic Abatement: Is there Enough Exposure to Cause Asbestos-related Disease?"
- Deer William Alexander, Howie Robert Andrew, Zussman Jack, ISBN 0-582-30094-0, OCLC 183009096 pp. 344–352, 1992
- Ledoux, RL (ed), Short course in mineralogical techniques of asbestos determination, Mineralogical Association of Canada, pp. 35–73, 185, 1979.
- http://www.microlabgallery.com/ChrysotileFile.aspx Photomicrographs of parachrysotile and clinochrysotile
- Nolan, RP, Langer AM, Ross M, Wicks FJ, Martin RF (eds), "The health effects of chrysotile asbestos", The Canadian Mineralogist, Special Publication 5, 2001.