Reconstructing Historical Exposures
There are many documented cases (e.g., asbestos, silica, and radon daughters) of a causal relationship between the health risk for disease and long-term exposure to airborne environmental contaminants. The biologically effective dose in such instances is related to the temporal history of an individual’s exposure, the kinetics of uptake and clearance of the inhaled material, and some measure of the harmfulness or potency of the contaminant. All of these are time-dependent quantities, and the integrated dose at time
since the start of the exposure may be expressed in a general form as
Dose = (18.1)
) is the exposure history derived from measurements of exposure concentration.