Requirements for accepted exposure assessment

Clearness and transparency with respect to the choice of models, methods, assumptions, distributions and parameters are two prerequisites for trust and confidence openness about uncertainties is another. Exposure assessment as an applied science should follow the main scientific desiderata empirical testing, documentation and reproducibility of results, explicit reporting of uncertainty, peer review and an open debate about underlying theories and models. This way, the main attributes for characterizing uncertainty discussed in the last chapter, the appraisal of the knowledge base and the subjectivity of choices, are clarified. 

It is unrealistic to expect a reviewer to be able to perform a complete assessment, unpaid and single handed. In the case of large models, a proper external assessment will require a multidisciplinary team, and a significant budget. [Morgan Henrion, 1990 p. 20] 

Point and range estimates as well as probabilistic models (Monte Carlo simulation) must show complete reproducibility per programming environment, since the underlying algorithms are deterministic. They should show asymptotic equivalence of results over different software environments and simulation techniques. 

The presentation of results should support an unbiased understanding of the results of the exposure assessment to enable the members of the target groups to make informed and independent decisions. This requires a basic understanding of the exposure process (the model from source to dose/burden) and at least an intuitive competence to understand the quantitative data and results in nature and magnitude. The selected scenario, data, model assumptions, results and inherent uncertainties should be communicated in an understandable and scientifically accepted presentation format. Presentations should be tailored to address the questions and information needs of the different audiences. To handle the different levels of sophistication and detail needed, it may be useful to design a presentation in a tiered format where the level of detail increases with each successive tier (USEPA, 1997b). 

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