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

The Salmonella mutagenicity assay and chemical analyses were used to e valuate 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 particulat e organics (2-12 revertants/mug) were generally greater than that of t he 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 produ ction of S9-dependent mutagens, such as polycyclic aromatic hydrocarbo ns (PAHs), under the combustion conditions generated by the CHUNK tire s. Bioassays using selected strains of Salmonella indicated that dinit roarenes 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 mutageni c emission factor for the open burning of scrap rubber tires (approxim ately 8 X 10(7) revertants/kg of tire burned) was 3-4 orders of magnit ude greater than the values for the combustion of oil, coal, or wood i n 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 emiss ion factor, posing potential environmental and health effects.