Marklund, S; Rappe, C; Tysklind, M; Egeback K-E
A study of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs) in automobile exhausts was conducted. Two test cars equipped with catalytic converters according to United States federal requirements and burning 95 octane unleaded gasoline and four cars burning the same gasoline but with added tetramethyllead (75741) and dichloroethane (1300216), 0.15 and 0.1 grams per liter, respectively, were used. The same motor oil was used in all cars. The exhausts were trapped and analyzed for PCDFs and PCDDS during a 12.4 kilometer running period. Emissions of carbon-monoxide (630080), hydrocarbons, and nitrogen oxides were also monitored. The measured carbon-monoxide, hydrocarbon, and nitrogen-oxide emissions indicated that the cars were in good condition and met the Swedish emission requirements. PCDDs and PCDFs were found in all samples from automobiles burning leaded gasoline. No PCDDs and PCDFs were found in exhaust samples where unleaded gasoline was used. Major PCDDs and PCDFs identified in cars burning leaded gasoline included 2,3,7,8-tetrachlorodibenzofuran (51207319), 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) (TCDD), 1,2,3,7,8-pentachlorodibenzofuran (57117416), 2,3,4,7,8-pentachlorodibenzofuran (57117314), and 1,2,3,7,8-pentachlorodibenzo-p-dioxin. The authors suggest that dichloroethane, used as a scavenger, could be the major source of the PCDDs and PCDFs found in cars burning leaded gasoline. The measured amounts of PCDDs and PCDFs emitted by cars burning leaded gasoline amount to approximately 10 to 100 grams of TCDD/equivalents annually. Additional amounts of PCDDs and PCDFs could occur in motor oil and mufflers.
