Respirable fraction

Safety. Magnesium oxide (fume) has a permissible exposure limit (PEL) (134) (8 hours, TWA), of 10 mg/m total dust and 5 mg/m respirable fraction. Tumorigenic data (intravenous in hamsters) show a TD q of 480 mg/kg after 30 weeks of intermittent dosing (135), and toxicity effects data show a TC q of 400 mg/m for inhalation in humans (136). Magnesium oxide is compatible with most chemicals exceptions are strong acids, bromine pentafluoride, chlorine trifluoride, interhalogens, strong oxidizers, and phosphorous pentachloride. 

Mishima, J., 1993, Recommended Values and Tedmical Bases for Airborne Relea.se Fractions (ARFs), Airborne Release Rates (ARRs), and Respirable Fractions (RFs) for Materials from Accidents in DOE Fuel Cycle, Ex-Reactor Facilities, Revision 2, Draft DOE report, April. 

Table 4 Respirable Fractions as Designated by the American Conference of Governmental and Industrial Hygienist and the U.S. Atomic Energy Commission... 

Aerodynamic diameter (pm) Respirable fraction (%) Respirable fraction11 (%)... 

TB Martonen, I Katz, K Fults, AJ Hickey. Use of analytically defined estimates of aerosol respirable fraction to predict lower lung deposition. Pharm Res 9 1634-1639, 1992. 

Wesley and Wall (4 ) and Brown and coworkers (18) collected dust samples at five cotton gins with high volume air samplers at three locations in the gin. The dust was removed from the filters in the seime manner as the weave room dusts discussed above. The average ash content was 32.9%. X-ray fluorescence analyses showed that silicon was the most abundant element detected (7.69%), followed by potassium (1.82%), aluminum (1.46%), calcium (1.15%), magnesium (1.05%), phosphorous (0.52%), iron (0.45%), sulphur (0.33%) and chlorine (0.16%). The total dust was separated into a "respirable fraction" (28) by the sonic sifting procedure and analyzed as above. The ash content of the respirable fraction of gin dusts increased to 46.0%. Only the... 

The 2003 ACGIH threshold limit value-time-weighted average (TLV-TWA) for diquat is 0.5mg/m for total dust and O.lmg/m for the respirable fraction of dust there is a notation for skin absorption. 

Pentaborane Diborane Decaborane Sodium borate Boron trifluoride Calcium borate Boron tribromide Boron oxide Total dust Respirable fraction Sodium tetraborate Decahydrate... 

Results showing the respirable fraction and total dust for different employees in the two processes are included in Tables IV and... 

In an attempt to increase the amount of particles retained in the lungs, large porous particles with low density (p < 0.1 g/cm2) have been designed (Edwards et al. 1997). The particles were composed of 50% lactide and 50% glycolide. Porous and nonporous particles loaded with testosterone were aerosolized into a cascade impactor system from a dry powder inhaler (DPI) and the respirable fraction was measured. Nonporous particles (d = 3.5 pm, p = 0.8 g/cm3) exhibited a respirable fraction of 20.5 3.5%, whereas 50 + 10% of porous particles (d = 8.5 pm, p = 0.1 g/cm3) were respirable, even though the aerodynamic diameter of the two particle types were nearly identical. Porous particles as a consequence of their large size and low mass density can... 

Ten years after the spread of activity, about two-thirds of the deposited Pu was in the top 50 mm of soil and reduced availability for resuspension probably accounts for the fall in air concentrations shown in Fig. 5.6. The region is moderately arid, with an annual rainfall of 400 mm, and the area near the source of Pu is untilled grassland. Because the Pu in air was mostly attached to soil particles, the particle size was large, and only about 25% was in the respirable fraction (Volchok etal., 1972). 

Volchok, H.L., Knuth, R. Kleinman, M.T. (1972) Respirable fraction of plutonium at Rocky Flats. Health Physics, 23, 395-6. 

EPA OAR Total dust Respirable fraction Standards of Performance for New Stationary Sources 15 mg/m3 5 mg/m3 OSHA 1974... 

NIOSH REL— Aluminum Total dust Respirable fraction Pyro powders Welding fumes Soluble salts Alkyls 10 mg/m3 TWA 5 mg/m3 TWA 5 mg/m3 TWA 5 mg/m3 TWA 2 mg/m3 TWA 2 mg/m3 TWA NIOSH 1992... 

Inhalation of dust irritates lungs. Ingestion causes abdominal pain and diarrhea. Highly toxic.1 TLV-TWA 0.01 (Cd)/m3 (total dust) TLV-TWA 0.002 (Cd)/m3 (respirable fraction of dust).6... 

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