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The kinetics and mechanism of the reactions C6H5CH202 + C6HsCH202 -2C6H5CH20 + 0 2 (3a), C&-CHzO2 + C~H S C H Z O~ -C&sCHO + C&CH2OH + 0 2 (3b), and CaHsCH202 + HOz -C&CHzOOH + 0 2 (4) have been investigated using two complementary techniques: flash photolysis/UV absorption for kinetic measurements and continuous photolysis/FTIR spectroscopy for end-product analyses and branching ratio determinations. The reaction of chlorine atoms with toluene was found to yield benzyl radicals exclusively and was used to generate benzylperoxy radicals in excess oxygen. During this study, relative reaction rate constants of chlorine atoms with compounds related to those involved in the reaction mechanism have been measured at room temperature: k(Cl+toluene) = (6.1 f 0.2) X lo-", k(Cl+benzaldehyde) = (9.6 f 0.4) X 10-11, k(Cl+benzyl chloride) = (9.7 f 0.6) X 10-l2, k(Cl+benzyl alcohol) = (9.3 f 0.5) X 10-11, k(Cl+benzene)< 5 X 10-l6, all in units of cm3 molecule-1 s-l. The products identified following the self-reaction 3 were benzaldehyde, benzyl alcohol, and benzyl hydroperoxide. The latter is the product of the reaction of C6H5-CHzO2 with HO2. The yield of products allowed us to determine the branching ratio ar = ksa/k3 = 0.4. The UV absorption spectrum of the benzylperoxy radical was determined from 220 to 300 nm. It was similar to those of alkylperoxy radicals, with a maximum cross section at 245 nm of 6.8 X 10-18 cm2 molecule.-' Kinetic data were obtained from the detailed simulation of experimental decay tracea recorded at 250 nm over the temperature range 273-450 K. The resulting rate expressions are k3 = (2.75 f 0.15) X 10-14 exp[(1680 f 140)K/T] cm3 molecule-l s4 and k4 = (3.75 f 0.32) X IO-" exp[(980 f 230)K/T) cm3 molecule-' s-1 (errors = la). The UV absorption traces in the flash-photolysis kinetic study were well accounted for by the identified products in the FTIR study, thus providing good confidence in the results. However, about 20% of the products have remained unidentified. Some uncertainties persist in the reaction mechanism leading us to assign a fairly large uncertainty of about 50% to the rate constants k3 and k4 over the whole temperature range. This work shows that the aromatic substituent does not provide any specificity in the reactivity of peroxy radicals and confirms that large radicals tend to react faster with H 0 2 than generally assumed in current atmospheric models.

Human breast adipose tissues were examined for 13 components and metabolites of technical chlordane. The geometric mean concentrations of heptachlor epoxide, oxychlordane, and trans-nonachlor were 48, 88, and 120 ng/g of fat, respectively. These concentrations increased with the subject's age, but were not much different from [1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980] values. The nanochlors and the pentachlorocyclopentene chlordanes are the most highly retained compounds in people, when compared to their abundances in technical chlordane. Chlordane accumulation in people was compared to its accumulation in other mammals, in fishes, and in invertebrates by using a calculated parent/metabolite ratio. The sources of chlordane exposure were evaluated, and it was concluded that exposure to chlordane in indoor air was an important source of these components to the U.S. population.

The purpose of this paper is to review current studies concerning the relationship of fuel composition to vehicle engine-out and tail-pipe emissions and to outline future research needed in this area. A number of recent combustion experiments and vehicle studies demonstrated that reformulated gasoline can reduce vehicle engine-out, tail-pipe, running-loss, and evaporative emissions. Some of these studies were extended to understand the fundamental relationships between fuel composition and emissions. To further establish these relationships, it was necessary to develop advanced analytical methods for the qualitative and quantitative analysis of hydrocarbons in fuels and vehicle emissions. The development of real-time techniques such as Fourier transform infrared spectroscopy, laser diode spectroscopy, and atmospheric pressure ionization mass spectrometry were useful in studying the transient behavior of exhaust emissions under various engine operating conditions. Laboratory studies using specific fuels and fuel blends were carried out using pulse flame combustors, single- and multicylinder engines, and vehicle fleets. Chemometric statistical methods were used to analyze the large volumes of emissions data generated from these studies. Models were developed that were able to accurately predict tail-pipe emissions from fuel chemical and physical compositional data. Some of the primary fuel precursors for benzene, 1,3-butadiene, formaldehyde, acetaldehyde and C2-C4 alkene emissions are described. These studies demonstrated that there is a strong relationship between gasoline composition and tail-pipe emissions.

The purpose of this paper is to review current studies concerning the relationship of fuel composition to vehicle engine-out and tail-pipe emissions and to outline future research needed in this area. A number of recent combustion experiments and vehicle studies demonstrated that reformulated gasoline can reduce vehicle engine-out, tail-pipe, running-loss, and evaporative emissions. Some of these studies were extended to understand the fundamental relationships between fuel composition and emissions. To further establish these relationships, it was necessary to develop advanced analytical methods for the qualitative and quantitative analysis of hydrocarbons in fuels and vehicle emissions. The development of real-time techniques such as Fourier transform infrared spectroscopy, laser diode spectroscopy, and atmospheric pressure ionization mass spectrometry were useful in studying the transient behavior of exhaust emissions under various engine operating conditions. Laboratory studies using specific fuels and fuel blends were carried out using pulse flame combustors, single-and multicylinder engines, and vehicle fleets. Chemometric statistical methods were used to analyze the large volumes of emissions data generated from these studies. Models were developed that were able to accurately predict tail-pipe emissions from fuel chemical and physical compositional data. Some of the primary fuel precursors for benzene, 1,3-butadiene, formaldehyde, acetaldehyde and C2-C4 alkene emissions are described. These studies demonstrated that there is a strong relationship between gasoline composition and tail-pipe emissions. -Environ Health Perspect 102(Suppl 4): 3-12 (1994).