Toxicity of Unwanted Intermediates and Products During Accidental Thermal Decomposition of Chemicals

The problem of the formation of unwanted substances that can occur during a thermal decomposition process is studied from a toxicological point of view. Starting from available data on the concentration profile of intermediates and product recorded during the thermal decomposition of a commonly used pesticide (Ethyl Paration), the use of the program ECOSAR shows that some species are more relevant from a toxicological standpoint than the initial compound. Since it is practically impossible to completely characterize the decomposition products of all the potential dangerous chemicals handled in the chemical industry, the result of ECOSAR calculation points out the necessity of developing a new experimental protocol devoted to fulfil the "Seveso II" directive. As a first attempt to solve this problem a preliminary screening based on toxicological tests is proposed. Encouraging results are obtained on Ethyl parathion thermal decomposition.