1.   Also present in the oil, and hence in the smoke from its combustion, were benzene and polycyclic aromatic hydrocarbons, both of which were carcinogenic.

2.   Organic compounds including a number of carcinogenic polycyclic aromatic hydrocarbons are also present in coal dust.

3.   Thames Water had the worst record for pesticides, as well as the biggest problem with polycyclic aromatic hydrocarbons, which are potentially carcinogenic.

4.   Among them are the polycyclic aromatic hydrocarbons, PAHs, which are known or suspected carcinogens.

5.   Diesel tailpipe pollution contains a mix of arsenic, benzene, dioxins and PAHs, or polycyclic aromatic hydrocarbons, among other things.

6.   It also contained polycyclic aromatic hydrocarbons of the kind formed by barbecuing.

7.   McKay said the polycyclic aromatic hydrocarbons were the molecules critical to the life question and they were almost certainly from Mars, and were not products of contamination.

8.   Neither study examined one type of organic molecule, polycyclic aromatic hydrocarbons, found in easily detectable amounts in the meteorite.

9.   One clue was chemicals called polycyclic aromatic hydrocarbons or PAHs, which on Earth are sometimes generated by biological processes.