BACTERIAL MUTAGENICITY OF PYROLYSIS TARS PRODUCED FROM CHLORO-ORGANICFUELS

Droplets of toluene and three chlorinated organics, ortho-dichlorobenz ene, 1,2-dichloroethane, and trichloroethylene, were pyrolyzed in pure nitrogen. The composition and bacterial mutagenicity of the product t ars were measured. The presence of organic chlorine was found to affec t both pyrolysis product tar composition and total tar mutagenicity. P yrolysis in the absence of chlorine produced tars whose bacterial muta genicity was found to be largely due to the presence of cyclopenta[cd] pyrene, fluoranthene, and benzo[a]pyrene. Small amounts of chlorine in the fuel (i.e., Cl/H molar ratios of less than 0.3) enhanced the form ation of highly condensed polycyclic aromatic hydrocarbons (including cyclopenta[cd]pyrene) and increased tar mutagenicity. Larger amounts o f organic chlorine (Cl/H ratios of between 0.3 and 0.6) resulted in si gnificant yields of mono- and dichlorinated aromatics and higher level s of tar mutagenicity, which could not be accounted for by the presenc e of mutagens produced by pyrolysis in the absence of chlorine. Furthe rmore, unlike tars containing little or no chlorine, tars containing a ryl chlorine were more mutagenic in the absence of added enzymes (inte nded to mimic in vivo mammalian metabolism) than in their presence. We hypothesize that at least one of the chlorinated aromatic products is strongly mutagenic. Two specific conditions that gave notably differe nt results were a) the low-temperature (ia., below 1400 K) pyrolysis o f ortho-dichlorobenzene, which produced tri- and tetrachlorinated biph enyls almost exclusively; and b) the chlorine-rich pyrolysis of trichl oroethylene, during which mostly perchloroaromatics were formed. Neith er of these tars Has found to mutate bacteria.