ផ្លាយ អាស់៖ ភាពខុសគ្នារវាងកំណែនានា
ខ្លឹមសារដែលបានលុបចោល ខ្លឹមសារដែលបានសរសេរបន្ថែម
បន្ទាត់ទី១៦៣៖
===ភ្នាក់ងារចំលង===
Fly ash contains trace concentrations of [[heavy metals]] and other substances that are known to be detrimental to health in sufficient quantities. Potentially toxic trace elements in coal include [[arsenic]], [[beryllium]], [[cadmium]], [[barium]], [[chromium]], [[copper]], [[lead]], [[mercury (element)|mercury]], [[molybdenum]], [[nickel]], [[radium]], [[selenium]], [[thorium]], [[uranium]], [[vanadium]], and [[zinc]]. Approximately 10 percent of the mass of coals burned in the United States consists of unburnable mineral material that becomes ash, so the concentration of most trace elements in coal ash is approximately 10 times the concentration in the original coal.<ref name="USGS" >{{cite web
|author = U.S. Geological Survey | authorlink = USGS
|title = Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and Environmental Significance
|date = October 1997
|url = http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.pdf
|work = U.S. Geological Survey Fact Sheet FS-163-97
|format=PDF
}}</ref> A 1997 analysis by the [[U.S. Geological Survey]] (USGS) found that fly ash typically contained 10 to 30 ppm of uranium, comparable to the levels found in some [[granite|granit]]ic rocks, [[phosphate]] rock, and black [[shale]].<ref name="USGS" />
In 2000, the [[United States Environmental Protection Agency]] (EPA) said that coal fly ash did not need to be regulated as a hazardous waste.<ref>{{cite web
|author = Environmental Protection Agency | authorlink = Environmental Protection Agency
|title = Notice of Regulatory Determination on Wastes From the Combustion of Fossil Fuels
| url = http://frwebgate.access.gpo.gov/cgi-bin/getpage.cgi?dbname=2000_register&position=all&page=32214
| work=Federal Register Vol. 65, No. 99
| page=32214
|date = May 22, 2000
}}</ref> Studies by the [[USGS|U.S. Geological Survey]] and others of radioactive elements in coal ash have concluded that fly ash compares with common soils or rocks and should not be the source of alarm.<ref name="USGS" /> However, community and environmental organizations have documented numerous environmental contamination and damage concerns.<ref name="McCabe, 2008, Chesapeake" >{{cite news
|first=Robert |last=McCabe | coauthors=Mike Saewitz
|title=Chesapeake takes steps toward Superfund designation of site.
|url=http://www.norfolk.com/2008/07/chesapeake-takes-steps-toward-superfund-designation-site?page=1
|publisher =''The Virginian-Pilot'' |date=2008-07-19
}}</ref><ref name="McCabe, 2008, Golf" >McCabe, Robert.[http://hamptonroads.com/2008/03/above-ground-golf-course-just-beneath-it-potential-health-risks "Above ground golf course, Just beneath if potential health risks"], ''[[The Virginian-Pilot]]'', 2008-03-30</ref><ref name="CCC, 2000" >Citizens Coal Council, Hoosier Environmental Council, Clean Air Task Force (March 2000), [http://www.catf.us/publications/reports/Laid_to_Waste.pdf "Laid to Waste: The Dirty Secret of Combustion Waste from America's Power Plants"]</ref>
A revised risk assessment approach may change the way coal combustion wastes (CCW) are regulated, according to an August 2007 EPA notice in the [[Federal Register]].<ref>{{cite web
|author = Environmental Protection Agency | authorlink = United States Environmental Protection Agency
|title= Notice of Data Availability on the Disposal of Coal Combustion Wastes in Landfills and Surface Impoundments
|date=August 29, 2007
|work=72 [[Federal Register]] 49714
|url = http://edocket.access.gpo.gov/2007/pdf/E7-17138.pdf
|format=PDF
}}</ref> In June 2008, the U.S. House of Representatives held an oversight hearing on the Federal government's role in addressing health and environmental risks of fly ash.<ref name="HCNR, 2008, Risks" >{{cite web
| author = House Committee on Natural Resources, Subcommittee on Energy and Mineral Resources
|title =Oversight Hearing: How Should the Federal Government Address the Health and Environmental Risks of Coal Combustion Wastes?
|date=June 10, 2008
|url = http://resourcescommittee.house.gov/index.php?option=com_jcalpro&Itemid=65&extmode=view&extid=184
}}</ref>
===ការព្រួយបារម្ភនឹងការប៉ះពាល់===
[[ស៊ីលីស|គ្រីស្តាល់ស៊ីលីស]](Crystalline silica) និង [[កំបោរ(រ៉ែ)|កំបោរ]](lime) រួមជាមួយនឹងសារធាតុពុលផ្សេងទៀត អាចបង្កជាបញ្ហាដល់សុខភាព។ ថ្វីបើខាងឧស្សាហកម្មបានអះអាងថា ផ្លាយអាស់ មិនមែនជាសារធាតុពុលនិងគ្មានសារធាតុពុលក៏ដោយ ក៏ការដកដង្ហើមយកសារធាតុអស់នេះ ការប៉ះពាល់ដោយផ្ទាល់ជាមួយនឹងស្បែក និងការផឹកទឹកដែលមានសារធាតុអស់នេះ ប្រហែលជាអាចបង្កគ្រោះថ្នាក់ដល់សុខភាព<ref>Managing Coal Combustion Residues in Mines, Committee on Mine Placement of Coal Combustion Wastes, National Research Council of the National Academies, 2006</ref> ។
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