Toxic Air Contaminant

Methanol use would also reduce pubHc exposure to toxic hydrocarbons associated with gasoline and diesel fuel, including ben2ene, 1,3-butadiene, diesel particulates, and polynuclear aromatic hydrocarbons. Although pubHc formaldehyde exposures might increase from methanol use in garages and tunnels, methanol use is expected to reduce overall pubHc exposure to toxic air contaminants. 

California EPA. 2001. Evaluation of methyl parathion as a toxic air contaminant. Department of Pesticide Regulation, California Environmental Protection Agency. Http //www.cdpr.ca.gov 8765/. January 19, 2001. 

EPA. 1986b. Extension of the public comment periods on notices of intent to list trichloroethylene and perchloroethylene as potentially toxic air contaminants. U.S. Environmental Protection Agency. Federal Register 51 9510. 

California maintains a list of Toxic Air Contaminants (TACs) and a program for adding additional TACs. 

Fossa AK, Riano MM, Lavin PJ, et al. 1984. New York State techniques and experience in regulating toxic air contaminants. Proceedings - Air Pollution Control Association Annual Meeting 77. 84- 6.2. 

ND Env. Health Sec. 1998a. Moderate toxicity air contaminants. North Dakota Environmental Health Section, State Department of Health and Consolitdated Laboratory. NDRSE33-24-01-04. 

NY Div. Air Res. 1998. Moderate toxicity air contaminants. New York Division of Air Resources, Department of Environmental Conservation. NY Air Guide 1. 

California Air Resources Board/Office of Environmental Health Hazard Assessment, Benzol a] pyrene as a Toxic Air Contaminant (1994) Office of Environmental Health Hazard Assessment/California Environmental Protection Agency, Air Toxics Hot Spot Program Risk Assessment Guideline, Part II Technical Support Document for Describing Available Cancer Potency Factors (1998) Collins et al. (1998). 

Clearly, a sound evaluation of the total mutagenic/carcinogenic potencies of a complex mixture of POM emissions (e.g., diesel exhaust) should include not only the PEFs of the primary particle- and vapor-phase PAHs and PACs but also those of the mutagens formed in atmospheric reactions of precursor PAHs (see, for example, Arey et al. (1992), Lewtas (1993b), Atkinson and Arey (1994), Nielsen et al. (1996), Arey (1998a), and Section F). For examples of such formal scientific health risk assessments prepared by the State of California Air Resources Board and Office of Environmental Health Hazard Assessment, see Benzo[ ]pyrene as a Toxic Air Contaminant (CARB, 1994) and Identification of Diesel Exhaust as a Toxic Air Contaminant (CARB, 1998). 

Atkinson, R and J. Arey, Lifetimes and Fates of Toxic Air Contaminants in California s Atmosphere, Final Report to the California Air Resources Board, Contract No. A032-055, 1993. 

California Air Resources Board (CARB), Identification of Benzofa]pyrene as a Toxic Air Contaminant, 1994. 

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 California Air Resources Board has prepared risk assessments for a number of toxic airborne compounds and mixtures, designated as toxic air contaminants, TACs (Table 16.15). For example, risk assessments for individual compounds such as benzene, benzo[a]pyrene (see Chapter 10), formaldehyde, and vinyl chloride have been carried out, in addition to complex mixtures such as diesel exhaust (California Air Resources Board, 1997a) and environmental tobacco smoke (California Environmental Protection Agency, 1997). These risk assessment documents form the basis for controls imposed as part of the risk management process (e.g., see Seiber, 1996). 

TABLE 16.15 Compounds or Mixtures Designated as Hazardous Air Pollutants (HAPs) in the United States" and Toxic Air Contaminants (TACs)b in the State of Californiab,c... 

Asterisks indicate HAPs for which the State of California has prepared detailed risk assessments and identified them as Toxic Air Contaminants (TACs). 

For a risk assessment, see Evaluation of Ethyl Parathion as a Toxic Air Contaminant, California Department of Food and Agriculture (1988). 

California Air Resources Board, Toxic Air Contaminant Identification List Summaries, September, 1997b. 

Seiber, J. N., Toxic Air Contaminants in Urban Atmospheres Experience in California, Atmos. Environ., 30, 751-756(1996). Seinfeld, J. H Ozone Air Quality Models A Critical Review, J. 

James N. Pitts, Jr., is a Research Chemist at the University of California, Irvine, and Professor Emeritus from the University of California, Riverside. He was Professor of Chemistry (1954-1988) and cofounder (1961) and Director of the Statewide Air Pollution Research Center (1970-1988) at the University of California, Riverside. His research has focused on the spectroscopy, kinetics, mechanisms, and photochemistry of species involved in a variety of homogeneous and heterogeneous atmospheric reactions, including those associated with the formation and fate of mutagenic and carcinogenic polycyclic aromatic compounds. He is the author or coauthor of more than 300 research publications and three books Atmospheric Chemistry Fundamentals and Experimental Techniques, Graduate School in the Sciences—Entrance, Survival and Careers, and Photochemistry. He has been coeditor of two series, Advances in Environmental Science and Technology and Advances in Photochemistry. He served on a number of panels in California, the United States, and internationally. These included several National Academy of Science panels and service as Chair of the State of California s Scientific Review Panel for Toxic Air Contaminants and as a member of the Scientific Advisory Committee on Acid Deposition. 

Occupational and toxicological studies have demonstrated adverse health effects from exposure to toxic air contaminants. Data on outdoor levels of toxic air contaminants have not been available for most communities in the United States, making it difficult to assess the potential for adverse human health effects from general population exposures. Models and new experiments provide a great amount of new data (Woodruff et al., 1998). 

If certain designated toxic air contaminants are emitted, the generator must comply with rules established under the toxic air contaminant program. Local APCD/AQMD... 

Where feasible, general ventilation design for low-level control of toxic air contaminants... 

Acute. Exposures occur for relatively short periods of time, generally from minutes to one to two days. Concentrations of (toxic) air contaminants are usually Iiigli relative to dieir protection criteria. In addition to iiilialation, airborne substances might directly contact die skin, or liquids and sludges may be splashed on die skin or into die eyes, leading to adverse healdi effects. This subject area falls, in a general sense, in die domain of hazard risk assessment (HZRA) and is addressed in die next two Parts (IV and V) of tills book. 

Environmental Defense. 2001. Asbestos. CalEPA Air Resources Board Toxic Air Contaminant Summary, Environmental Defense. Http //www.scorecard.org/chemical-profiles/html/asbesots.html. January 19, 2001. 

Quinone is formed as yellow crystals and has a characteristic irritating odor like that of chlorine. It is slightly soluble in water, alcohol, ether, hot petroleum ether, and alkalis. Quinone is an oxidizing agent and is reduced to hydroquinone. It has been declared a federal hazardous air pollutant and was identified as a toxic air contaminant in April 1993 under AB 2728. 

Has been identified by the EPA as a chemical likely to leach dangerous concentrations of toxic chemicals into ground water. Also classified as a toxic air contaminant. 

The U.S. EPA is charged with addressing air pollution under the Clean Air Act. The poor air quality found in California has led the state of California to establish the California Air Resources Board (ARB), which also addresses this subject. EPA has established a list of hazardous air pollutants anci ARB has established a Toxic Air Contaminant (TAC) Identification List. 4 Numerous other literature references identify still other known air pollutants. Table 7.1, toxic chemicals in the air, which was compiled from these sources, shows the range of pervasive toxic chemicals that are found in the air we breathe. 

California Air Resouces Board. Toxic air contaminant identification list, www. arb. ca. gov/toxics/quickref.htm... 

Catalytic hydrotreatment is widely used in the petroleum Industry to remove sulfur, nitrogen, and oxygen from crude oil fractions. However, its use to treat chlorocarbons has not been widely reported despite the widespread use of these compounds in industrial and military operations, and despite the negative environmental impact associated with most disposal options. Catalytic hydrotreatment has the potential to be a safe alternative for the treatment of chlorinated wastes and has advantages over oxidative destruction methods such as thermal incineration and catalytic oxidation. Some of these advantages include the ability to reuse the reaction products, and minimal production of harmful byproducts, such as CI2, COCI2, or fragments of parent chlorocarbons. 1,1,1- Trichloroethane was chosen for this research because it is widely used in industry as a solvent and is on the EPA Hazardous Air Pollutant list as a toxic air contaminant and ozone depleter. ... 

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