ENSC 201 Mineral Dusts Particulates Natural Dust Silica Dust

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ENSC 201 Mineral Dusts Particulates Natural Dust Silica Dust Powered By Docstoc
					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
                    jamieson@geol.queensu.ca                         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




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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




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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




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