Investigation on the carcinogen burden by air pollution in man. XV. Polycyclic aromatic hydrocarbons in automobile exhaust gas--an inventory.

Polycyclic aromatic hydrocarbons (=PAH) emitted by two different vehicles were separated by gas chromatography and characterized by mass spectrometry after enrichment from exhaust gas condensate. Gasoline was investigated also using this technique. The quantities of PAH with boiling points higher than 338 degrees C contained in the exhaust gas were compared to those present in the fuel. About 150 different PAH have been characterized by mass spectrometry, 75 of these were identified by means of comparison with authentic samples. Six compounds of the PAH-group consisting of 4-7 rings, which are suspected of possessing carcinogenic activity, are described here for the first time. Structures of these hitherto unidentified PAH are proposed by means of MS and UV spectral informations (11H-cyclopenta(qrs)benzo(e)-pyrene, 10H-cyclopenta(mno)benzo(a)pyrene, benzo(ghi)cyclopenta(pqr)perylene, cyclopentenopyrene). According to the different PAH-profiles of the fuel and of the exhaust gas, it is concluded that the main part of the PAH emitted is produced de novo during the combustion in the engine and furthermore that the PAH contained in the fuel are combusted for the most part.