Evaluation of Exposure Information

Abstract

Steps toward the development of a generally applicable and deterministic model for retrospective exposure assessments are suggested. The first step is the introduction of a set of n universally applicable and mutually independent exposure modifiers, chosen according to first principles. The second step is the provision of a list of these exposure modifiers to be used in a multiplicative model. The historic concentrations can then be obtained from present measured concentrations by calculating backwards step by step. If some historic exposure data are available, they can be used as gauging points and the model parameters can be renormalized accordingly. The ranges of the magnitude of the various modifiers differ by several orders of magnitude. This should be considered when deciding which historic information should be traced. Information sources should be searched systematically for exposure-related data. The term industrial archeology is phrased, and this activity is illustrated with a dendrochronological study of deposits in a ventilation duct. Measurements in developing countries should be considered before attempting simulations of past exposure scenarios. The coupling between the physical environment and the human behavior, the notion that control technology is often used selectively on the most significant sources, and the fact that changes are not necessarily felt at their full value by all members of a group present problems for the model. The sensitivity of the model to these factors should be estimated. The large range in the value of the modifiers shows that good documentation of environmental conditions is important. The application of good surveying techniques, the refinement of initial exposure assessment methods, and the development of deterministic, retrospective, exposure assessment models go hand in hand.