User:Saltwolf/template asbestos

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Asbestos
Fiber Types
Products
Health Issues
Removal and Abatement
Litigation and Legislation
NGOs and Seminars


Health problems[edit]

Left-sided mesothelioma (seen on the right of the picture): chest CT

All types of asbestos fibers are known to cause serious health hazards in humans.[1][2][3] While it is agreed that amosite and crocidolite are the most hazardous asbestos fiber types, chrysotile asbestos has produced tumors in animals and is a recognized cause of asbestosis and malignant mesothelioma in humans.[4]

Mesotheliomas have been observed in people who were occupationally exposed to chrysotile, family members of the occupationally exposed, and residents who lived close to asbestos factories and mines.[5] According to the NCI, "A history of asbestos exposure at work is reported in about 70 percent to 80 percent of all cases. However, mesothelioma has been reported in some individuals without any known exposure to asbestos."[6] The most common diseases associated with chronic exposure to asbestos include: asbestosis and pleural abnormalities (mesothelioma, lung cancer).[7] Asbestosis has been reported primarily in asbestos workers, and appears to require long-term exposure, high concentration for the development of the clinical disease. There is also a long latency period (incubation period of an infectious disease, before symptoms appear) of about 12 to 20 years.[8]

Studies have shown an increased risk of lung cancer among smokers who are exposed to asbestos compared to nonsmokers.[9]

Asbestos exposure becomes a health concern when high concentrations of asbestos fibers are inhaled over a long time period.[10] People who become ill from inhaling asbestos are often those who are exposed on a day-to-day basis in a job where they worked directly with the material. As a person's exposure to fibers increases, because of being exposed to higher concentrations of fibers and/or by being exposed for a longer time, then that person's risk of disease also increases. Disease is very unlikely to result from a single, high-level exposure, or from a short period of exposure to lower levels.[10]

Possible Mechanisms of Carcinogenicity[edit]

Stanton and Layard hypothesized in 1977–78 that toxicity of fibrous materials is not initiated by chemical effects;[11] that is, any trigger-effects of asbestos must presumably be physical, such as (A) mechanical damage or (B) unwanted signal channels (a plausible property for slender transparent fibres) which might disrupt normal cell activity—especially mitosis.

(A) Mechanical Damage. There is experimental evidence that very slim fibers (<60 nm, <0.06 μm in breadth) do tangle destructively with chromosomes (being of comparable size).[12][13] This is likely to cause the sort of mitosis disruption expected in cancer.

(B) Unwanted Signal channels. This has recently been explored theoretically, but not yet experimentally. The theory argues that this effect would only be feasible for asbestos fibers >100 nm in breadth (>150 nm in the case of chrysotile), which suggests that we should be on the look-out for a possible mixture of different mechanisms for the different fiber-diameter-ranges.[14][15]

One popular idea of the causal chain is (1) Asbestos fiber → → (3) inflammation → (4) other pathology. While that may be true, it does not explain "(2), the actual trigger":

"What is the physical property of asbestos which initiates any such inflammation?" (After all, inflammation is usually seen as caused by chemical-based processes: immunological &/or bacterial). So inflammation (&/or oxidation etc.) may well be part of the causal chain, but not the crucial first step.[14]

Other asbestos-related diseases[edit]

Main article: Asbestos-related diseases
  • It is important to consult a doctor, particularly if the following symptoms develop: shortness of breath, wheezing, or hoarseness, persistent cough that worsens over time, blood in fluid coughed up, pain or tightening in chest, difficulty swallowing, swelling of neck or face, decreased appetite, weight loss, fatigue or anemia.[16]
  • Asbestosis: Progressive fibrosis of the lungs of varying severity, progressing to bilateral fibrosis, honeycombing of the lungs on radiological view with symptoms including rales and wheezing. Individuals who have been exposed to asbestos via home, environment, work should notify their doctors about exposure history.
  • Asbestos warts: caused when the sharp fibers lodge in the skin and are overgrown causing benign callus-like growths.
  • Pleural plaques: discrete fibrous or partially calcified thickened area which can be seen on X-rays of individuals exposed to asbestos. Although pleural plaques are themselves asymptomatic, in some patients this develops into pleural thickening.
  • Diffuse pleural thickening: similar to above and can sometimes be associated with asbestosis. Usually no symptoms shown but if exposure is extensive, it can cause lung impairment.
  • Pneumothorax: Some reports have also linked the condition of pneumothorax to asbestos related diseases.
  1. ^ World Health Organization fact sheet on asbestos disease
  2. ^ International Agency for Research on Cancer (IARC) Special Report, 2009 as published in The Lancet Oncology, May, 2009
  3. ^ Collegium Razmzzini 2010 Statement on Asbestos
  4. ^ Kanarek, Mesothelioma from Chrysotile Asbestos: Update, Annals of Epidemiology, Volume 21, Issue 9 , Pages 688–697, September 2011
  5. ^ Marbbn, C.A. (2009). "Asbestos Risk Assessment". The Journal of Undergraduate Biological Studies: 12–24.
  6. ^ Mesothelioma: Questions and Answers, National Cancer Institute
  7. ^ ATSDR – Asbestos – Health Effects. (1 April 2008). ATSDR Home. Retrieved 24 January 2011
  8. ^ Mossman, BT; Churg, A (1998). "Mechanisms in the Pathogenesis of Asbestosis and Silicosis". American Journal of Respiratory and Critical Care Medicine. 157 (5 Pt 1): 1666–80. PMID 9603153.
  9. ^ Berry, G.; Newhouse, Muriell.; Turok, Mary (1972). "Combined Effect Of Asbestos Exposure And Smoking On Mortality From Lung Cancer In Factory Workers". The Lancet. 300 (7775): 476. doi:10.1016/S0140-6736(72)91867-3.
  10. ^ a b "2001.09.16: (Fact Sheet) Asbestos". U.S. Department of Health & Human Services. 16 September 2001. Archived from the original on 14 July 2008. Retrieved 2010-01-12.
  11. ^ Stanton,M.F., and Layard,M. (1978). The carcinogenicity of fibrous minerals. National Bureau of Standards Special Publication 506 – from Gaitherburg conference of July 1977.
  12. ^ Voytek P., Anver T.Thorslund (1990). "Mechanisms of Asbestos Carcinogenicity". J. Amer. College of Toxicology. 9 (5): 541–550. doi:10.3109/10915819009078762.
  13. ^ Toyokuni S (2009). "Mechanisms of asbestos-induced carcinogenesis". Nagoya J. Med. Sci. 71 (1–2): 1–10. PMID 19358470.
  14. ^ a b Traill, R.R. (2010). The theoretical case that some asbestos fibers could trigger cancer optically, while others act mechanically. Ondwelle Publications: Melbourne.
  15. ^ Traill, Robert R (2011). "Asbestos as 'toxic short-circuit' optic-fibre for UV within the cell-net: — Likely roles and hazards for secret UV and IR metabolism". Journal of Physics: Conference Series. 329: 012017. Bibcode:2011JPhCS.329a2017T. doi:10.1088/1742-6596/329/1/012017.
  16. ^ Asbestos Exposure and Cancer Risk – National Cancer Institute. Cancer.gov. Retrieved on 2012-01-10.
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