Computer risk considerations

The WHO emphasized that guideline values for carcinogenic substances computed using mathematical models must be considered at best as a rough estimate of the cancer risk, as these models do not usually take into account a number of biologically important considerations, such as toxicokinetics, DNA repair, or immunological protection mechanisms. However, the models used are conservative and probably err on the side of caution. 

In the past, risk assessment consisted largely of computer-based models written to start from hazard assessment assays, such as chronic toxicity assays on rodents, encompass the necessary extrapolations between species and between high and low doses, and then produce a numerical assessment of the risk to human health. Although the hazard assessment tests and the toxic end points are different, an analogous situation exists in environmental risk assessment. A matter of considerable importance, now getting some belated attention, is the integration of human health and environmental risk assessments. 

Fig. 9-9 demonstrates the results of MVDA for the three investigated territories in the plane of the computed two discriminant functions. The separation line corresponds to the limits of discrimination for the highest probability. The results prove that good separation of the three territories with a similar geological background is possible by means of discriminant analysis. The misclassification rate amounts to 13.0%. The scattering radii of the 5% risk of error of the multivariate analysis of variance overlap considerably. They demonstrate also that the differences in the multivariate data structure of the three territories are only small. 

Consideration must be given to the potential effects of the computer system and associated equipment on the personnel who may use or come into contact with the system. Typically these risks are associated with the interfacing to Visual Display Units (VDUs) and environmental conditions. 

Expert Systems as "Automated Documents." Sometimes a user needs to make a decision based upon the consideration of categorical or qualitative information, rather than calculations involving numerical parameters. Expert Systems comprise several types of computer programs that address this type of information. Risk Assistant will contain a variety of small expert systems that assist users in different aspects of the risk assessment process. 

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