Receptor exposure, chronic risk assessment

The exposure characteristics and assumptions refer partly to site conditions e.g. soil type, soil chemistry, exposed soil fraction) and partly to the site use and users e.g- construction style of buildings, receptor characteristics, activity patterns and time spent on site). Many of these are assumptions rather than measurements because chronic health risk assessments are concerned with predicting contaminant intakes and their effects up to 70 years into the future. Some of the soil characteristics may also change with time. 

Let us take a closer look at the analysis of exposnre to a toxic chemical. If the ecological receptor is a population of fish, such as coho salmon, a useful measure of exposure is the concentration of the toxic chemical in water. If the ecological receptor is a population of birds, exposure analysis is performed in much the same way as the estimate of chronic daily intake in a human health risk assessment (Chapter 8). The measure of interest is the average daily dose (ADD) in units of milligrams of... 

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