Project Summary (1995-2000)

The formation of mutagens during the pyrolysis and oxidation of wastes at Superfund sites is determined in order to provide a basis for assessing the potential risks from high temperature destruction of wastes. The surrogate wastes studied have been selected because of their relevance to Superfund sites in general and to the Aberjona site in particular. The products of interest are: a) polycyclic aromatic hydrocarbons (PAHs); b) chlorinated mutagens; c) polychlorinated biphenyls (PCBs), which are known precursors to dioxins and dibenzofurans; and d) arsenic and chromium submicron aerosols and residual particles. The specific aims of the project are to understand and control the chemistry responsible for mutagen formation, to gain insight on the effect of chlorine on the chemical pathways of organic by-product formation, to determine the biological activities- using human cells mutation assays- of the combustion and pyrolysis products, to test and refine chemical kinetic models which can be used to interpret the experimental results and to forecast product formation in different combustion conditions, to identify parameters that are responsible for variations in the product spectrum, and the selection of control strategies with the objectives of minimizing health risks- assessed by mutagenicity studies- posed by pyrolytic and oxidative thermal destruction processes. Research activities define the pathways to soot growth and mutagen formation in oxidative and pyrolytic high-temperature environments, on the effect of chlorine on mutagen formation and distribution, and on the influence of temperature on the mechanisms of growth and fragmentation of chemical species. Both empirical and theoretical methods are employed in these pyrolysis studies.