MUTAGENICITY AND CHEMICAL-ANALYSIS OF EMISSIONS FROM THE OPEN BURNING OF SCRAP RUBBER TIRES

The Salmonella mutagenicity assay and chemical analyses were used to evaluate the emissions from the open burning of scrap rubber tires that had been cut into either of two sizes, CHUNK or SHRED. The mutagenic potencies in strain TA98 of the dichloromethane-extractable particulate organics (2-12 revertants/mug) were generally greater than that of the semivolatiles (approximately 1-9 revertants/mug). In addition, the open burning of CHUNK tires produced a higher burn rate (approximately 4-9 vs approximately 1 kg/h) and more potent organics in the presence of S9 than did SHRED tires. This may have reflected the greater production of S9-dependent mutagens, such as polycyclic aromatic hydrocarbons (PAHs), under the combustion conditions generated by the CHUNK tires. Bioassays using selected strains of Salmonella indicated that dinitroarenes or aromatic amines (but not mononitroaromatics) accounted for much of the mutagenic activity measured in the absence of S9. A wide variety of PAHs was detected in the particulate organics. The mutagenic emission factor for the open burning of scrap rubber tires (approximately 8 X 10(7) revertants/kg of tire burned) was 3-4 orders of magnitude greater than the values for the combustion of oil, coal, or wood in utility boilers; it was most similar to values for the open burning of wood or plastic. These results demonstrate for the first time that the open burning of scrap rubber tires produces a high mutagenic emission factor, posing potential environmental and health effects.