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ENSC 201 Winter 2005 Particulates SIZE Greatest health hazard is associated with particulates less than 10 microns (.001 mm) ENSC 201 Particulates <2.5 microns (.00025 mm) can be inhaled into lower lung Mineral Dusts Larger particles can be ingested orally into gut March 10, 2005 SHAPE Fibres and barbed fibres particularly hazardous Dr. H. Jamieson (asbestos) Miller Hall Room 304 CHEMISTRY email@example.com Particulates may be hazardous because of physical and chemical nature (e.g. lead) Natural Dust Health hazards of transported dust • There is much more soil dust than anthropogenic dust over large areas of the earth • Carribean countries receive significant • North Africa and China are major sources of globally- amounts of African dust: asthma transported dust outbreaks can be correlated with storms • Images show large storm in Feb 2000 • New concern: long-range transport of pathogens carried with dust Respiratory hazard associated with crystalline silica Silica Dust depends on size and degree of crushing. • Silicosis (“miner’s asthma”) long recognized as a workplace disease • Silica and silicates common in soil dust • Crystalline silica (quartz) may be carcinogen • How can we regulate the second most common 6 cm crystals sub-microscopic crystals mineral on Earth (quartz) ? • Present in bricks, ceramics, concrete, Hazardous: sand-blasting, some mining and quarrying sandpaper, toothpaste, paper, kitty litter, etc. Non-hazardous: handling kitty litter or potting soil, going to the beach 1 ENSC 201 Winter 2005 Asbestos •Crocidolite “blue asbestos”: • Known to be carcinogenic if inhaled mined in South Africa, considered most dangerous • Refers to several minerals that crystallize as fine, long (3:1), flexible fibres •Tremolite: see case study on • Fire-retardant, found in many building components Libby, MT •Minerals can be distinguished by X-ray analysis • chrysotile • “white asbestos”: •Removing asbestos from • most common ore buildings is more dangerous (mined in Quebec) than leaving it there Case Study – Libby, Montana Vermiculite Vermiculite: clay mineral that expands into wormy shapes when heated Used for insulation, horticulture, etc. Mined in Libby since 1920’s Bought by W.R. Grace in 1963 Closed in 1990 Libby vermiculite is naturally contaminated with asbestiform tremolite Libby vermiculite was used to make Zonolite, a house insulation product used throughout North America. Asbestiform tremolite in Libby vermiculite However, hazardous exposure is probably limited to workers and residents. Family members were exposed by doing laundry. Standardized mortality rates from Libby Size of sample area increases to right Excavation by EPA of vermiculite waste piles in Libby http://www.atsdr.cdc.gov/HAC/PHA/libby/lib_toc.html 2 ENSC 201 Winter 2005 Study of garden, street and house Indoor Household Dust dusts in 50 houses in Ottawa • Canadians spend 90% of our time indoors mg/kg Garden Street House Dust Dust Soil • Toddlers ingest dust through hand-to- Lead 107 68 969 mouth acitivity Cadmium 0.4 0.6 15.3 Mercury 0.09 0.06 6.57 Arsenic 4 2 13 Iron 25950 25660 19120 Manganese 662 534 366 (Health Canada, 2002) Toxicology of fine particulate matter from WTC • Samples collected on Sep 12 and 13 • Fine fraction (<2.5 micron) was tested on mice • Consisted mostly of gypsum and calcite which are common in building materials • Little carbon from combustion • Caused mild to moderate inflammation • Equivalent to 8 hours of human exposure • Particulates high for approximately one month Gypsum from WTC collapse Scale bar is 2 microns Chrysotile from WTC collapse (rare) Scale bar is 2 microns 3
"ENSC 201 Mineral Dusts Particulates Natural Dust Silica Dust"