Toxic species atmosphere

The physical characteristics of individual particles also are of environmental significance. For example, the smaller particles (diameters on the order of 1 micrometer of less) generally are most important in that they have very long atmospheric residence times (18), are least effectively controlled by pollution control devices (19), are preferentially deposited in the pulmonary regions of the lung (20,21), and may be most enriched in toxic species on a specific concentration (iig/g) basis (22-24). 

A number of species have been designated hazardous air pollutants (HAPs) or toxic air contaminants (TACs). Most are directly emitted into the air, but some also have significant secondary sources, i.e., are formed by chemical reactions in air. Furthermore, the ultimate health impacts are determined not only by the emissions and formation of such compounds in air but also by their atmospheric fates. In short, some pollutants react in air to form less toxic species, whereas others form more toxic compounds. Thus, scientific risk assessments of these pollutants require an accurate and complete understanding of their atmospheric chemistry. Some specific examples are discussed in this chapter. 

The presence of impurities and additives such as PVC as a fire retardant in polyurethanes has also been detected by means of TG-MS analysis [144], PU foam containing the flame retardant tetrakis (2-chloroethyl) ethylenediphosphate decomposes in an oxidative atmosphere at standard pressure in one rapid reaction whereby several highly toxic species are formed the TG-MS detection limit of this flame retardant was determined [166]. The most striking fact is the very early generation of vinylchloride from the flame retardant, while HCN is produced at much higher temperatures. 

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

The environmental impact of tin is appreciable, as it is one of the three most enriched metals—only lead and tellurium precede—in the atmospheric particular matter, as compared with the abundance of the element in the earth crust (2.2 ppm). Tin releases to the environment can be methylated by aquatic organisms, yielding organometallic species of toxicity comparable to that of methylated mercury5. 

Data Adequacy Although human data are limited to primarily occupational monitoring studies, the data base on animal studies is good. The test atmosphere in the key study was supplied via a face mask to the restrained test subjects restrained animals have been shown to be more sensitive than unrestrained animals to inhaled toxicants. Relative species sensitivity to inhaled HCN may be related to breathing rate. Compared to rodents, the slower breathing rate of humans and monkeys may make them less sensitive to the effects of HCN. 

Gardner DR, Panter KE, Pfister JA, Knight AP. 1999. Analysis of toxic norditerpenoid alkaloids in Delphinium species by electrospray, atmospheric pressure chemical ionization, and sequential tandem mass spectrometry. J Agric Food Chem 47 5049. 

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