Risk assessment representation

PBPK models improve the pharmacokinetic extrapolations used in risk assessments that identify the maximal (i.e., the safe) levels for human exposure to chemical substances (Andersen and Krishnan 1994). PBPK models provide a scientifically sound means to predict the target tissue dose of chemicals in humans who are exposed to environmental levels (for example, levels that might occur at hazardous waste sites) based on the results of studies where doses were higher or were administered in different species. Figure 3-4 shows a conceptualized representation of a PBPK model. 

Knowledge of the relationship between dose and response (effect), and the threshold for this, is crucial in defining the risk of exposure to a chemical. Safety evaluation is a legal requirement for drugs, food additives, and contaminants in food, and a risk assessment has to be carried out in order to set the limits of exposure. The relationship between the dose and the response (effect) can be established and plotted as a graph. This is called a dose-response curve (see Figure 29 and box), which often shows that there is a dose(s) of the chemical that has no effect and another, higher dose(s) which has the maximum effect. It is a visual representation of the Paracelsus principle that, at some dose, all chemicals are toxic. The corollary to this is that there is a dose(s) at which there is no effect. 

Any individual with a professional interest in exposure analysis is invited to join. The Society seeks broad participation from various disciplines such as exposure assessment, chemistry, biochemistry, risk assessment, biostatistics, physiology, toxicology, epidemiology, ecology, environmental engineering, and others. There are currently several hundred members of ISEA, with a US focus but international representation. Students and international professionals with an interest in exposure assessment are especially encouraged to join. 

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