Selenium aerosol

Figure 5. Particle-size distribution of selenium aerosols ( ) 400°C, (O) 375°C...

Lead, tellurium, and selenium aerosols in 0.01 to 1 micrometer size range could be generated using a condensation aerosol technique. The particle size is dependent on the generation temperature. The aerosol output is dependent on both the generation temperature and the carrier gas flow rate. 

The stability and reproducibility were excellent for lead and tellurium aerosols. Selenium aerosol output decreased with time at a given temperature. 

Weissman et al. (1983) reported that selenium concentrated in the liver, kidney, spleen, and lungs of dogs following inhalation exposure to selenious acid or elemental selenium aerosols. 

Medinsky MA, Cuddihy RG, McClellan RO. 1981b. Systemic absorption of selenious acid and elemental selenium aerosols in rats. J Toxicol Environ Health 8 917-928. 

Aerosol concentrations in excess of 4.0 jag Se/m3 are potentially harmful to human health (Harr 1978). Concentrations in excess of this value (6.0 pg Se/m3) were regularly encountered in the vicinity of the smeltery at Sudbury, Ontario, Canada (Nriagu and Wong 1983). It is not now known whether respiration rates of wildlife, particularly birds, are comparable to those of humans, whether selenium absorption energetics are similar, or whether wildlife species that frequent point sources of air contaminated by high selenium levels for protracted periods are at greater risk than humans. Until additional and more conclusive data become available, aerosol concentrations of less than 4.0 pg Se/m3 are recommended for the protection of sensitive wildlife species. 

Hopke, et al. (4) and Gaarenstroom, Perone, and Moyers (7) used the common factor analysis approach in their analyses of the Boston and Tucson area aerosol composition, respectively. In the Boston data, for 90 samples at a variety of sites, six common factors were identified that were interpreted as soil, sea salt, oil-fired power plants, motor vehicles, refuse incineration and an unknown manganese-selenium source. The six factors accounted for about 78 of the system variance. There was also a high unique factor for bromine that was interpreted to be fresh automobile exhaust. Large unique factors for antimony and selenium were found. These factors may possibly represent emission of volatile species whose concentrations do not oovary with other elements emitted by the same source. 

Weissman SH, Cuddihy RG, Medinsky MA. 1983. Absorption, distribution, and retention of inhaled selenious acid and selenium metal aerosols in beagle dogs. Toxicol Appl Pharmacol 67 331-337. 

In coastal seawater such as the Western Mediterranean basin, soil-derived particles originated from arid areas (in this case the Sahara). The atmospheric flux of anthropogenic trace metals, however, was dominated by aerosols from industrialized regions of Western Europe. Volcanic activity (Mount Etna) contributes selenium. The atmospheric input of Cr, Hg, Pb, and Zn into the Western Mediterranean basin is of the same order of magnitude as the riverine and coastal inputs of these components (Arnold et al. 1983). For the southern bight of the North Sea, estimates even indicate a predominance of the atmospheric input of... 

A small fraction of selenium may exist in the gaseous state in the atmosphere (Table 7.2). However, the majority of atmospheric selenium is expected to be present in particulate form (NAS 1976). Removal of atmospheric selenium occurs primarily through wet and dry deposition and its association with sub-micrometer aerosols (Mosher and Duce 1983, NAS 1976, Jickells etal. 1984). Selenium is emitted naturally into the atmosphere mainly in the form as dimethylselenide (Jiang et al. 1983). Major producers of dimethylselenide are plants and soil bacteria (Terry et al. 2000). Through bacterial and phytovolatilization substantial amounts of selenium may be removed from selenium-contaminated soil. Inor-... 

Prophylactic induction of enzymes involved in the conjugation of xenobiotics reduced or prevented the acute toxic effects of T-2 toxin in the rat, while inhibition of these enzymes resulted in a higher toxicity for this trichothecene.96 Pretreatment with flavonoids,97 ascorbic acid,98 vitamin E," selenium,100 or chemoprotective compounds such as emetine101 that block trichothecene-cell association all reduce acute toxicity of these mycotoxins. However, none of these chemoprotective treatments have undergone extensive efficacy studies to evaluate their ability to protect against an aerosol or dermal exposure to trichothecene mycotoxins. 

Aerosol concentrations exceeding 4.0 jxg Se/m are considered potentially harmiful to human health however, no comparable database for birds and other wildlife species is available at this time. Selenium poisoning in livestock is prevented if diets do not exceed 5.0 mg Se/kg natural forage, or... 

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