Estimation of the respiratory tract burden resulting from a prolonged inhalation exposure to aerosols of du, based on the U in a 24-h urine sample taken years after exposure

A procedure is presented to estimate the respiratory tract burden from a prolonged inhalation exposure to particulate matter of depleted uranium, in cases where the rate of deposition is an unknown function. The precise range of possible values is identified. The calculations are based on the amount of depleted uranium measured in a single 24-h urine sample. In order to present an example, a simplified pharmaco-kinetic model is introduced. The results presented in this article are valid for any pharmaco-kinetic model represented by homogeneous linear differential equations with constant coefficients and non-zero initial values, and that clearly includes the International Commission on Radiological Protection model. In fact, they are applicable to any monitorable quantity measured over a short period of time, a monitorable quantity with a kinetic that can be described using a structurally similar system of differential equations to one describing these pharmaco-kinetic models. (authors)