Amorphous silica dust

Vitums VG, Edwards MJ, Niles NR, Borman JO Pulmonary fibrosis from amorphous silica dust. A product of silica vapor. Arch Environ Health 32 62-68, 1977... 

SYNS ACTICEL AEROSIL AMORPHOUS SILICA DUST AQUAFIL CAB-O-GRIP II CAB-O-SIL CAB-O-SPERSE CATALOID COLLOIDAL SIUCA COLLOIDAL SILICON DIOXIDE DAVISON SG-67 DICALITE DRI-DIE PESTICIDE 67 ENT 25,550 FOSSIL FLOUR FUMFX) SILICA FUMED SILICON DIOXIDE O LUDOX NALCOAG NYACOL NA ACOL 830 NYACOL 1430 SANTOCEL SG-67 SIUCA, AMORPHOUS SILICIC ANHYDRIDE SIUCON DIOXIDE (FCQ SIUKILL VULKASIL... 

Metal Surface Composition To determine which metal bound to surfaces of road dust, soil dust was collected that contained larger particles (400 to 3000 nm diameter in air) and that compared closely to amorphous silica dust (6, 7). This dust was thought to be composed of both particles ground from the Earth s emst and particles generated by transportation vehicles that drive on the roads from which road dust was collected. Dust was collected near a road in four fractions. <56 nm, <100nm, both ultrafine (nano) particle aerosols, a fraction <2500 nm (a fine aerosol), and one < 10,000 nm (a coarse aerosol). Different elements were enriched on the surface of different-sized particles (6, 7). 

Synonyms cas 112945-52-5 acticel aerosil amorphous silica dust aquafil cAB-o-oRipn cab-o-sil... 

Amorphous silica dust See Silica, fumed Amorphous silica gel. See Silica, amorphous AMP. SeeAminomethyl propanol... 

CAS 112945-52-5 EINECS/ELINCS 231-545-4 Synonyms Amorphous silica dust Cl 77711 Colloidal silica Colloidal silicon dioxide Eossil flour Eumed silica Fumed silicon dioxide Pigment white 27 Silica, amorphous Silica, amorphous fumed Silica, pyrogenic Silicic anhydride Silicon dioxide Definition High surface area aggregate particles of silica, with min. 89.5% SiOj content Empirical OjSi Formula SiOj... 

CAS 112945-52-5 EINECS/ELINCS 231-545-4 Synonyms Amorphous silica dust Cl 77711 Colloidal silica Colloidal silicon dioxide Fossil flour... 

Under actual working conditions silicosis involving fibrosis of the lungs is not caused by amorphous silica dust, but rather by quartz dust. However, in innumerable studies, the effects of particle size were not clearly separated from differences in crystallinity. 

From a practical standpoint there are very few conditions under which amorphous silica (glass) dust could be encountered in the dangerous 1-4 micron size range. Almost all amorphous silica dusts consist of particles at least two. orders of magnitude smaller than this. On the other hand, almost all silica dusts in the 1-4 micron range encountered in industry are crystalline—usually quartz. 

G. W. H. Schepers The Biological Action of Flame Process Submicron Amorphous Silica Dust, AMA Arch. Ind. Health, 16, 125, 203, 363 (1957). 

Amorphous silica dust. See Silica, fumed Amorphous silica gel. See Silica, amorphous AMP. See Aminotrimethylene phosphonic acid Aminomethyl propanol t-AMP. See p-t-Amylphenol AMPD. See Aminomethyl propanediol AMPD-isostearoyl hydrolyzed collagen CAS 169590-82-3... 

Inhalation of crystalline or fused vitreous silica dust, usually overlong periods, causes a disabling, progressive pulmonary disease known as silicosis (84). Amorphous siUcas have not been linked to siUcosis (85), but can cause respiratory irritation. The history and poHtics of siUcosis have been reviewed (86). Standards have been set or recommended for occupational exposures (87,88) and review articles on the health effects of siUca are available (83,89). 

A soft, gritty amorphous silica composed of minute siliceous skeletons of small aquatic plants. Used in filtration and decoloration of liquids, insulation, filler in dynamite, wax, textiles, plastics, paint, and rubber. Calcined and flux-calcined diatomaceous earth contains appreciable amounts of cristobalite, and dust levels should be the same as for cristobalite. 

Silica, amorphous Silica, crystalline Silica in coal mine dust Silicon... 

The nuisance dust aspect of bauxite is in sharp contrast to the limited industrial situation where lung injury was reported in Canadian workers, who in the 1940s engaged in the manufacture of alumina abrasives in the virtual absence of fume control. Fusing of bauxite at 2000°C gave rise to a fume composed of freshly formed particles of amorphous silica and aluminum oxide. Despite the poor choice of the term—bauxite fume pneumoconiosis—sometimes used to describe the disease, scientific opinion favors the silica component as the probable toxic agent. It should be emphasized that bauxite from some sources may contain small amounts of silica. 

The 2003 ACGIH proposed threshold limit value-time-weighted average (TLV-TWA) for amorphous silica, natural diatomaceous earth, is lOmg/m for the inhalable particulate and 3mg/m for respirable dust containing no asbestos and <1% quartz. 

Adverse effects on the lungs of workers exposed to the fumes of ferrosilicon furnaces have been recognized since 1937. Subsequent clinical studies of workers exposed to amorphous silica fume in silicon and ferrosilicon plants reported pulmonary symptoms and X-ray findings difficult to differentiate from classic silicosis due to crystalline silica, especially because there is often concurrent exposure to quartz dust during furnace operations. 

Amorphous silica is classified by the Occupational Safety and Health Administration as a nuisance dust. The principal reported health reaction is contact dermatitis resulting from the absorption of protective oils from the skin (1). 

The amount of BSA measured in an initial concentration range of 10 to 1000 mg/L adsorbed on Qzm dusts, is compared in Figure 3A with the amount of BSA adsorbed on A50. Qzm and A50 exhibit different affinities for BSA with increasing protein concentration the coverage on amorphous silica increases up to a value of 500 pg/rrr, and on quartz the amount of BSA adsorbed reaches 1500 pg/rrr. In both samples, the amount of BSA adsorbed does not reach the monolayer value (around 2 mg/m2), assuming that the protein adsorbs sideways-on. 

The determination of quartz dust in the air samples in industrial workplace is an established procedure. Although capable of collecting the particulates, organic polymer membranes can not be employed as an XRD substrate since the diffuse diffraction lines at or near the 10 angle of quaru makes polymeric membtanes not suitable for this application [Minneci and Paulson, 1988]. It is possible to quantify as low as 0.005 mg quartz under well controlled conditions (Bumsted, 1973]. Similarly, silver membranes can also be used as a collecting medium and XRD substrate for measuring crystalline and amorphous silica, lead sulfide, boron carbide and chrysotile asbestos [Leroux and Powers. 1970]. 

A desiccant dust containing amorphous silica gel in combination with 1.00% pynelhrins and 10.00% PBO can be applied as a crack and crevice treatment against fleas and lice and may also be applied directly to the animal. A companion formulation containing 0,50% pyrethrins and 5.00% PBO in a silica gel base is designed for use on zoo and laboratory animals including monkeys, chimpanzees and rodents. Both products kill lice, fleas, and ticks on contact by a combination of physical dehydration and chemical action. 

Various industries use large quantities of fumed and precipitated silica (amorphous silica). These forms of silica do not cause silicosis but protection from exposure to dust must be provided because any excessive dust decreases efficiency of lungs. ... 

The fact that particles of 5 jam and less, as used in HPLC, may pass into the lungs (they are not retained by the bronchial tubes but pass straight through) is less well known and the potential long-term risk to health has not yet been adequately researched. Amorphous silica, as used for stationary phases, is not hazardous but inhalation should be avoided anyway. As a safety precaution, any operation involving possible escape of stationary phase dust (opening phials, weighing etc.) must be carried out in a fume cupboard. 

---