Aromatic Hydrocarbons from Vehicular Exhausts

Abstract

THE greater frequency of cancer of the lung in urban over rural populations has been well established. This has prompted the evaluation of the aetiological relevancy of agents which have been introduced or which have increased in quantity in urban atmosphares in recent years. Thus, Kotin, Falk andThomas (1954, 1955), sampling the particulate phase of exhausts from both petrol and diesel engines, identified seven polycyclic hydrocarbons spectroscopically, including the traditional animal carcinogen, 3, 4-benzpyrene, and showed their differential formation with respect to engine speed and load.The present paper records an assay for aromatic hydrocarbons of a sample of petrol exhaust soot produced under the varying conditions of normal automobile running and compares the results with those obtained from a sample of general atmospheric soot. A sample of diesel exhaust soot, collected as the engine idled, was similarly investigated. EXPERIMENTALThe twin exhaust pipes of a 3.6-litre private car were muzzled with fine hemp sacks and an exhaust sample collected over a short period of normal motoring. The sacks and contents were extracted by refluxing with acetone. The acetone extract was taken to dryness and the residue extracted by refiuxing for three 3-hour periods with petroleum-ether (B.P. 60-80°C .). The combined extracts were taken to a small volume, and the free carbon of the residual soot estimated. The concentrated extract was fractionated by adsorption chromatography.The following chromatographic procedure was employed. The concentrated extract, which contained 4.56 g. of extracted material, was layered on top of a 30 x 4 cm. column of alumina (100-200 mesh) and developed with 60-80°p etroleum-ether. The progress of the fractionation in this and subsequent chromatograms, was followed by periodic inspection of the columns under a filtered U.V. lamp. All columns were screened from diffuse daylight by wrappings of black paper, to minimize incidental photo-oxidation.In the initial chromatogram, a fast moving slightly fluorescent oil was detected in the eluate. For the full development of the chromatogram, chloroform was incorporated in the eluent to a concentration of 40 per cent. Thus more strongly adsorbed components were eluted. In all, twelve fractions were collected.As considerable overlapping of zones occurred, each fraction was separately chromatographed on 20 x 2.5 cm. columns of 100-200 mesh alumina (Spence). The first three fractions were chromatographed using petroleum-ether as eluent.The remaining nine fractions were each developed with petroleum ether containing

Air Pollution

“…Polycyclic Aromatic Hydrocarbons. These compounds have been found in garages (82), vehicular exhaust, (251,256), rural and urban air (77), smoke and tar from a curing kiln (421), oysters from polluted water (58), soot from human lungs (120), and other related sources.…”

Part III. Chemistry, host entry, and metabolic fate of carcinogens

“…5 , 9, 28. 33. : 18 In addition, a number of related PAll with carcinogenic potency have been detected in polluted air or in engine exhausts. 24,25,30 Chemical studies Carcinogenic agents. Benzo( a )pyrene has been used as the indicator of the presence of carcinogenic PAR in environmental sources.…”

Characterization of Hazardous Solid Waste (Soot) Accumulated in Tailpipe of Typical Indian Share Autos

“…The soot particles can condense quickly on different surfaces of graphite rods, quartz tubes, ceramic tubes, fire bricks and materials of Fe, Co and Ni 23 . A fraction of total particulates consists of metal oxides, heavy metals, PAHs and trace elements originating from incomplete diesel combustion, lubricating oils and engine material due to engine-wearing process [24][25][26][27] . Primary soot generated in the engines has been observed to increase in size along the exhaust path 28 .…”