QSAR approach to POPs screening for atmospheric persistence

The environmental behaviour of a persistent organic pollutant (POP) is main ly controlled by its persistence, its tendency to undergo long-range transp ort (LRT) and its physicochemical properties. Atmospheric half-life is one of the criteria commonly used to study air persistence and LRT potential. F or the 12 UNEP POPs and another 48 possible POPs, the mean and maximum half -life estimations for degradation in air are modelled using different molec ular structure descriptors (atom and fragment counts, topological and WHIM descriptors), selected by Genetic Algorithm, in QSAR regression models. Bot h values are modelled to obtain an average estimate and a precautionary val ue for ranking and screening purposes. The models, validated for their pred ictivity, could be applied to predict unavailable data. Principal component analysis (PCA) was then used to explore the half-life data in addition to the physicochemical properties that are most relevant to atmospheric mobili ty; the aim has been to screen and rank POPs with regard to their tendency towards atmospheric persistence and mobility, and to obtain a persistence i ndex in air and an LRT index. These indexes were also modelled by molecular descriptors, thus allowing a preliminary screening of new compounds, (C) 2 001 Elsevier Science Ltd. All rights reserved.