Analysis of automobile exhaust condensates

1. On the basis of figures for the production of PAH during the Europa drive cycle by 100 passenger cars and those for the consumption of petrol in the Federal Republic of Germany, an annual emission of 1,850 kg benzo[a]pyrene from petrol engine vehicles has been calculated. 2. The carcinogenic effect of benzo[a]pyrene accounts for only 9% of the total activity of exhaust condensates. 3. The amounts of other known carcinogenic PAH, such as benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene are shown in Table 2. (table: see text). Assuming that there is no significant promoting or hyper-additive effect, it can be estimated that these six known carcinogenic PAH contribute about 10-15% of the total carcinogenicity. 4. Six unknown PAH were found: cyclopenteno[cd]pyrene (mol wt 226), methylenebenzo[a]pyrene (mol 264), methylenebenzo[e]pyrene (mol wt 264), methylenebenzo[ghi]perylene (mol wt 288), PAH mol wt 300A and PAH mol wt 300B. It is reasonable to assume that these unknown PAH account for the predominant part of the carcinogenic effect. Biological tests with these pure substances are being undertaken by Drs Pott, Pfeiffer and Habs. 5. It has been shown that almost all of the carcinogenic effect of automobile exhaust condensates is due to PAH. To support this claim, the carcinogenic effects of the exhaust condensate should be compared with those of a mixture of the known and unknwon PAH in the same proportions as are found in the exhaust condensate. The gas chromatogram of such a mixture is shown in Figure 6.