On aspects of the dynamic behavior of persistent chemicals in a multimedia environment related to exposure-based hazard assessment

Journal of Mathematical Chemistry (Impact Factor: 1.27). 08/2010; 48(2):290-304. DOI: 10.1007/s10910-010-9669-3

ABSTRACT The present research study focuses on the analysis and characterization of certain aspects of the dynamic behavior displayed
by persistent chemicals in a multimedia environment (chemodynamics), which is jointly determined by the inherent physicochemical
properties of the chemical substance under consideration, as well as underlying environmental processes such as degradation
in different phases/media (soil, water and air) coupled with intermedia transport (interphase mass transfer). In particular,
dynamic multimedia environmental models are considered with constant source terms describing steady chemical release/discharge
rates into various environmental media of interest, and key risk-related aspects of the dynamic behavior of persistent chemicals
are analyzed using perturbation theory techniques under conditions where degradation rates in different media are considerably
slower than intermedia transport rates. Under the above conditions, the problem of defining physically meaningful and practical
quantitative measures of overall persistence of chemicals in a multimedia environment is revisited, given its role as a key
exposure-based indicator within all major chemical risk assessment frameworks, and a proof is provided that rigorously establishes
equivalence between two important and popular persistence measures, namely the characteristic time at steady state and the
inverse of the associated chemodynamics overall decay rate (slowest chemodynamic mode).

KeywordsChemical dynamics-Multimedia environmental models-Persistence-Exposure-based hazard assessment-Perturbation theory

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